a r X i v :0709.3635v 1 [a s t r o -p h ] 23 S e p 2007
Mon.Not.R.Astron.Soc.000,000–000(0000)Printed 2February 2008
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High redshift FRII radio sources:large-scale X-ray environment
E.Belsole 1,2?,D.M.Worrall 2,M.J.Hardcastle 3,&J.H.Croston 3
1
Institute of Astronomy,University of Cambridge,Madingley Road,Cambridge,CB30HA,U.K.
2Department of Physics,University of Bristol,Tyndall Avenue,Bristol BS81TL,U.K.
3
School of Physics,Astronomy and Mathematics,University of Hertfordshire,College Lane,Hat?eld,Hertfordshire AL109AB,U.K.
Accepted 2007July 27.Received 2007July 27;in original form 2007May 19
ABSTRACT
We investigate the properties of the environment around 20powerful radio galaxies and quasars at redshifts between 0.45and https://www.doczj.com/doc/4c11868683.html,ing XMM-Newton and Chandra observations we probe the spatial distribution and the temperature of the cluster gas.We ?nd that more than 60per cent of powerful radio sources in the redshift range of our sample lie in a cluster of X-ray luminosity greater than 1044erg s ?1,and all but one of the narrow-line radio galaxies,for which the emission from the nucleus is obscured by a torus,lie in a cluster environment.For broad-line quasars the X-ray emission from the core dominates and it is more dif?cult to measure the cluster environment.However,within the statistical uncertainties we ?nd no signi?cant difference in the properties of the environment as a function of the orientation to the line of sight of the radio jet.This is in agreement with uni?cation schemes.Our results have important implications for cluster surveys,as clusters around powerful radio sources tend to be excluded from X-ray and Sunyaev-Zeldovich surveys of galaxy clusters,and thus can introduce an important bias in the cluster luminosity function.Most of the radio sources are found close to pressure balance with the environment in which they lie,but the two low-excitation radio galaxies of the sample are observed to be under-pressured.This may be the ?rst observational indication for the presence of non-radiative particles in the lobes of some powerful radio galaxies.We ?nd that the clusters around radio sources in the redshift range of our sample have a steeper entropy-temperature relation than local clusters,and the slope is in agreement with the predictions of self-similar gravitational heating models for cluster gas infall.This suggests that selection by AGN ?nds systems less affected by AGN feedback than the local average.We speculate that this is because the AGN in our sample are suf?ciently luminous and rare that their AGN activity is too recent to have caused the onset of measurable feedback and increased entropy in the clusters,especially in the cooler ones where locally the effect of feedback are expected to be most evident.If this is con?rmed by forthcoming X-ray missions it will improve our understanding of the heating and cooling processes in high-redshift galaxy clusters.
Key words:galaxies:active –galaxies:high redshift –quasars:general –radio continuum:galaxies –X-rays:galaxies:clusters
1INTRODUCTION
Much evidence supports the existence of a gaseous environment around powerful radio galaxies and quasars.Theoretically,mod-els of jet con?nement imply that an external medium with pres-sure similar to the pressure found at the centre of galaxy clusters is required to keep the jet collimated (Begelman,Blandford,&Rees 1984).Observationally,two of the most powerful radio galax-ies,Cygnus A (Arnaud et al.1984;Reynolds &Fabian 1996)and 3C 295(e.g.Henry &Henriksen 1986;Allen et al.2001),are lo-cated in the centre of rich clusters of galaxies.Studies based on optical observations ?nd that,at redshift ～0.2?0.3,power-?
E-mail:elena@https://www.doczj.com/doc/4c11868683.html,
ful Fanaroff-Riley type II (FRII)sources are found in relatively modest environments (group scale,e.g.,Hill &Lilly 1991;Zirbel 1997;Wold et al.2000;Best 2004,and references therein),while at higher redshifts the environments of FRIIs may again be rich clusters with richness comparable to Abell class I or higher (e.g.,Hall &Green 1998).This evidence is provided mainly by stud-ies based on galaxy over-densities,gravitational arcs (Deltorn et al.1997;Wold et al.2002)and lensing shear of surrounding ?eld galaxies (Bower &Smail 1997).Hence it has been apparent for many years that powerful radio galaxies and quasars should act as sign-posts of massive galaxy clusters at high redshift.
The clearest observational evidence for the existence of a cluster around a radio source is the detection of an X-ray emit-ting,thermal,large-scale medium surrounding https://www.doczj.com/doc/4c11868683.html,ing ROSAT
2 E.Belsole et al.
Table1.The sample
RA(J2000)Dec(J2000)redshift scale type N H Literature 3C6.1
073924.31+702310.740.9948.00NLRG 3.45B04 3C200
084047.58+131223.370.6847.08LDQ 4.12Br02/G03 3C220.1
095010.70+142000.070.552 6.42NLRG 3.18this work 3C254
113957.03+654749.470.646 6.90LDQ 1.18CF03/H02 3C265
124357.67+162253.220.557 6.40LDQ 1.99CF03 3C280
135041.95+642935.400.713 6.90NLRG 2.17B04 3C295
145907.60+714019.890.9047.80GPS-Q 2.30this work 3C330
162021.85+173623.120.555 6.38LDQ 4.24this work 3C345
182931.78+484446.450.6917.11CDQ 5.67this work 3C427.1
225357.76+160853.720.8597.68CDQ 6.50this work
High redshift FRIIs:large-scale X-ray environment3
on the effect of the environment on the radio galaxy properties and the accretion mechanisms at various look-back times.Furthermore, a comparison between environments of radio sources with jets at different angles to the line of sight is a powerful way of testing orientation-based uni?cation models.
In this paper we present the?rst systematic X-ray study of the extended emission from powerful radio galaxies at z>0.45to have been carried out with the current generation of X-ray satel-lites,using a moderately large sample of20radio galaxies and quasars from the same catalogue.Of the20sources,11have previ-ously published studies of their extended X-ray emission;5of these were studied by our group.Table1gives references to the literature for these objects.Clusters around5more sources are detected in this paper for the?rst time.The X-ray properties of the nuclei of this sample were discussed in Belsole,Worrall,Hardcastle(2006). The lobe IC emission from most of the sources was described in Croston et al.(2005b).In this paper we report the properties of the external environments around the sources in our sample.
Throughout the paper we use a cosmology with H0=70km s?1Mpc?1,?m=0.3,?Λ=0.7.If not otherwise stated,errors are quoted at the1σcon?dence level.
2THE SAMPLE
This study is based on the sample described in Belsole et al.(2006). Sources are taken from the3CRR catalogue(Laing et al.1983), which is selected on the basis of low-frequency(178-MHz)ra-dio emission,and are in the redshift range0.45 The sample is composed of a similar number of broad-line quasars and narrow-line radio galaxies.Table1lists the main prop-erties of the sources including their quasar classi?cation. Preparation of the Chandra data is described in Belsole et al. (2006).However for this paper we re-processed the data with CIAO 3.3.0.1and CALDB v3.2.4,and added observation ID4843of 3C454.3and ID2254of3C295.XMM-Newton data preparation is described in Belsole et al.(2004),and we use the same data and results for this analysis.In Table2we give details of the X-ray observations used in this work.3SPATIAL ANALYSIS 3.1Imaging Diffuse,thermal X-ray emission associated with a cluster-like envi-ronment is best detected at soft energies,between0.5and2.5keV, as this is the energy range where the Chandra and XMM-Newton mirrors are the most sensitive.Thermal bremsstrahlung cluster ra-diation peaks in this energy range,while the nuclear X-ray compo-nent and the lobe inverse-Compton emission tends to have a harder spectrum.For this reason we generated images of each source in the 0.5-2.0keV(soft)and2.5-7.0keV(hard)energy bands(we adopt a separation of500eV in order to avoid features associated with the Si edges,and also to ensure that the two energy bands do not overlap).We then applied a wavelet reconstruction algorithm pro-vided by A.Vikhlinin1as an ef?cient way to search for extended emission not associated with the PSF,and at a detection limit of 4.5σabove the background level at the location of each pixel.In Appendix A we show for each source observed with Chandra the wavelet-decomposed and reconstructed images in the soft and hard band.The same analysis for3C184and3C292was presented by Belsole et al.(2004)and so is not repeated here.The radio emis-sion at1.4GHz is shown by the superimposed logarithmic contour. The comparison between the images at soft and hard energy bands gives an immediate indication of the presence of extended X-ray emission which may be associated with an external environment of the radio source.For most of the sources,extended X-ray emission seems to be associated with the radio lobes,but many of the sources also show more symmetrical emission which tends to fade at high energy. 3.2Radial pro?le We carried out a more quantitative characterisation of the spatially extended emission by extracting a radial pro?le of each source. The pro?le was centred on the emission peak of each source,and point sources other than the central AGN were excluded.Here we focus on extended emission associated with the external en-vironment and not the extended non-thermal X-ray emission asso-ciated with the lobes(Croston et al.2005b).Although in Croston et al.we showed that many of the sources in the sample con-tribute very few counts to the lobe emission,to be conservative we excluded the spatial regions coincident with the radio lobes before extracting the radial pro?le.The masked area was prop-erly taken into account when deriving physical parameters.Any emission at radio frequencies from the CDQs–not discussed in Croston et al.(2005b)–is within5arcsec of the centre of the source and so not relevant to the analysis discussed here.For details of the detection of X-ray counterparts of three of the sources see Sambruna et al.(2002)(3C345),Marshall et al.(2005)(3C380), and Marshall et al.(2005);Tavecchio et al.(2007)(3C454.3). We used the energy band0.5-2.5keV which optimises the in-strument sensitivity to the soft thermal emission over the AGN and particle contributions.Exposure corrections were applied using a map calculated at the peak energy of the global spectrum,which was found to be at1keV for most of the sources.When multiple exposures were available,the radial pro?le was extracted from a mosaic event list and the mosaic exposure map was used.The back-ground region was chosen by selecting an annular region between the distance from the centre at which the radial pro?le becomes?at 1https://www.doczj.com/doc/4c11868683.html,/RD/zhtools/ 4 E.Belsole et al. Table2.Observation log.Col1:3CRR name;Col.2:Instrument used for the observations,C stands for Chandra,X for XMM-Newton;Col.3:Observation ID;Col.4:Nominal exposure Time;Col.5:Net exposure time,after?are screening.For XMM-Newton observations we give times for mos/pn detectors;Col. 6pileup fraction. Instrument Obs ID EXPOSURE Screened time pileup 3C6.1 C30093635.75 3C184 X002854020138.932/–na C8381614.71 3C207 C8392118.57 3C228 C209515.513.83 3C254 C21265148.826 3C265 C20962624.84 3C280 X014754010133.920/17<1 3C295 C31051716.66 3C330 C20973330.29 3C345 C3124 5.5 5.316 3C427.1 C3127 5.5 5.524 and at which it increases because particle-dominated background has been erroneously corrected for vignetting.The inner radius of the background annulus is speci?c to each source(see Table3).We limited our analysis to the S3chip in all cases but3C295(ACIS-I), and the background area was also selected from this chip. To assert the presence of extended emission,modelling of the PSF is crucial,especially in the context of these sources which har- bour bright AGN.To obtain the best representation of the central point source emission we generated a model of the PSF at the off- axis position of each source using the Chandra Ray Tracer(ChaRT) and MARX2.We used the option of giving the spectrum of the source as the input parameter in order to generate a PSF model appropriate for the spectral distribution.The output?le of ChaRT was then used to generate an event list of the PSF using MARX. We then extracted a radial pro?le of the PSF for each source and used this model to?t the source radial pro?le.We adopted an it- erative process as the PSF model is dependent on the blurring pa- rameter which is an input to MARX.We changed this parameter in order for the PSF to?t the?rst two bins of the radial pro?le of the source.For sources with a pileup fraction of more than10per cent we used MARX to generate a piled-up PSF model and we used this event list as the best representation of the point source.Radial pro?les were initially?tted with a PSF.When this was not an ac- ceptable?t,we added aβ-model.We varied theβparameter and core-radius,r c,when the photon statistics were suf?cient to carry out a two-parameter?t.In all other cases we?xed theβand r c parameters to values(generally2/3,and120-150kpc)commonly observed in local clusters,allowing for the possibility that clusters at high redshift are more concentrated(i.e.smaller core radii and 2https://www.doczj.com/doc/4c11868683.html,/chart/ Figure1.Bolometric X-ray luminosity distribution.The shaded area corre- sponds to the radio galaxies sub-sample βthan canonical values in the local universe should not be seen as unusual).The results of the radial pro?le?tting are listed in Table 3,and the individual?ts can be inspected in Appendix A for the sources observed with Chandra,while for3C184and3C292,ob- served with XMM-Newton,the pro?les are shown in Belsole et al. (2004). 4SPECTRAL ANALYSIS We selected the spatial region for spectral extraction on the basis of the shape of the radial pro?le.We initially extracted a background- High redshift FRIIs:large-scale X-ray environment5 Figure2.Top:Bolometric X-ray luminosity versus radio power of each galaxy as measured at178MHz.Middle:Bolometric X-ray luminosity versus redshift.Bottom:Bolometric X-ray luminosity versus Full-Width-Half-Maximum(r F W HM)de?ned as in Eq.2.Only sources for which?tting ofβand r c were possible are used for this plot. 6 E.Belsole et al. Table3.Radial pro?le modelling results.Col.1:source3CRR name;Col.2:quality?ag,where C implies a detection of extended emission with constrained structural parameters,D implies a detection with F-test probability for having an extended component>98per cent but unconstrained structural parameters, and P implies a point-like source with no detected extended emission;Col.3:best-?tting beta parameter;Col.4:best-?tting core radius;Col.5:number of counts predicted by the best?ttingβ-model included in a circle of radius corresponding to the detection radius R det.;Col.6:external radius of the last annulus used to integrate the pro?le,this is also the radius of the inner circle of the annulus used for background subtraction;Col.7:number of counts predicted by the best?ttingβ-model out to a distance from the centre corresponding to R200;Col.8:distance from the centre corresponding to the radius at which the density of the cluster is equal to an over-density of200;Col.9:Central surface brightness of theβ-model;Col.10:χ2/d.o.f.corresponding to the best-?tting β-model+PSF.If“UL”a3σupper limit was calculated using appropriate values ofβand r c;Col.11:χ2/d.o.f.corresponding to the best-?tting PSF model only;Col.12:F-test null probability that the two-component model gives an improved?t for random data. qual beta r c cnt det.R https://www.doczj.com/doc/4c11868683.html,t(R200)R200S0χ2/d.o.f.χ2F-test prob. 3C6.1 D0.66f20.0f63±6087.567+118 ?25 7900.03±0.020.6/5 3.13/6 5.90e-3 3C200 D0.80+0.20 ?0.306.1+3.9 ?4.8 342±4319.8506+958 ?103 1146 3.46±0.43 4.61/667.60/9 6.76e-4 3C220.1 D0.5f15.0f122±3878.7214±14010720.05±0.01 5.81/716.37/89.13e-3 3C254 P0.67f10f<90464.0<9681173<1.66UL86.50/12N/A 3C265 P0.60f7.0f<11319.7<129494<0.34UL7.54/7N/A 3C280 C0.80+0.50 ?0.2519.7+26.8 ?14.0 523±66100.0528+111 ?68 7070.40±0.05 1.62/765.08/10 5.61e-6 3C295 C0.56+0.19 ?0.041.78+4.24 ?1.33 141±2639.4164+122 ?42 366 3.76±0.680.87/329.40/68.57e-3 3C330 P0.67f10.0f<15535.4<191496<0.35UL 3.54/8N/A 3C345 P0.50f7.0f<10588.6<109677<0.13UL15.98/9N/A 3C427.1 P0.50f 5.0f<38529.5<480413<1.27UL14.47/9N/A High redshift FRIIs:large-scale X-ray environment7 Table4.Spectral analysis:Col.1:source3CRR name;Col.2:radius of the circle used to integrate the spectrum.This may be smaller than the outer circle used to extract the radial pro?le;Col.3:number of net counts in the energy range0.5-2.5keV contained in the area used for the spectral analysis.This is lower than the number of counts in the radial pro?le as the area masked before extracting the pro?le is larger to account for the point source emission.When two values are listed it means that two exposures have been used.For3C184and3C292we list the counts from the whole EPIC;Col.4:best-?t mekal model temperature and1σerrors for one interesting parameter;Col.5:chemical abundances used for the?t.The Grevesse&Sauval(1998)table for solar abundances was adopted and all values were?xed;Col.6:Normalisation of the MEKAL model;Col.7:χ2/d.o.f.corresponding to the best-?tting model;Col. 8:unabsorbed X-ray?ux in the energy range0.5-2.5keV;Col.9:unabsorbed X-ray luminosity of the thermal component in the energy range0.5-2.5keV; Col.10:total(bolometric)X-ray luminosity of the thermal component within the detection radius of the spectrum;Col.11:Bolometric X-ray luminosity. This was calculated by extrapolating the number of counts out to the virial radius using the radial pro?le distribution and using the count rate to adjust the normalisation of the spectral model to obtain the bolometric X-ray luminosity.Errors are the quadratic sum of the statistical errors derived from the spectral and radial pro?le analyses. R cnts k T Z/Z⊙Normχ2/dof f X(×10?14L X(×1043L Bol sp X L Bol X (×1044 0.5-2.5keV0.5-2.5keV0.5-2.5keV erg s?1)Extrapol. 49.260+14 2.0f0.5<3.24UL<0.72<2.1<0.59<0.71 3C184a 24.679 3.91+7.67 ?1.820.3 3.40+0.63 ?0.69 7.27/10C 1.26+0.24 ?0.52 0.10.260.73+0.15 ?0.33 3C207 24.6338 4.65+1.29 ?0.890.316.38+1.18 ?1.12 10.86/13 5.2+0.39 ?0.34 6.9 1.86 6.94+1.14 ?0.90 3C228 34.482? 1.54+7.06 ?0.870.5 1.33+0.87 ?0.43 1.62/30.34+0.22 ?0.11 0.90.18 1.67+1.12 ?0.59 3C263 24.616 1.05+0.34 ?0.460.50.55+0.23 ?0.25 4.73/5C0.14+0.06 ?0.06 0.60.100.23+0.11 ?0.11 3C275.1 20.053 5.0f0.3 1.52+0.34 ?0.390.41/3C0.34+0.07 ?0.09 1.30.40 1.48+1.08 ?1.08 3C292a 108.280344.74+0.26 ?0.23 0.48±0.08133±5163/19052±2369.8616.1±0.6 3C309.1 39.4146 1.59+3.78 ?0.630.2 2.57+0.30 ?0.97 1.48/6C0.63+0.07 ?0.24 0.820.170.31+0.09 ?0.14 3C334 39.437? 2.0f0.5<4.43UL<1.150.200.40<1.3 3C380 24.6168 5.66+9.59 ?2.350.3 3.39+0.60 ?0.57 3.94/3 1.2+0.20 ?0.20 1.270.38 3.5+0.60 ?2.10 3C454.3 ?counts are partially from the wings of the PSF and have been modelled before extracting the thermal model values. a See Belsole et al.(2004)for details.For3C184the number of counts and theχ2correspond to the whole spectral region(nucleus not excluded)and?tted model.For3C292,the area used for the spectral analysis was an ellipse on major and minor semi-axis equal to101and64arcsec respectively.A sector in the region corresponding to the radio lobes was also excluded. b3C263:All counts are from a point source;3C184:part of the counts are from the point source as it cannot be resolved with XMM data C C-statistics were used,and the values quoted are the C-statistic parameter and the Pulse Height Amplitude(PHA). mostly due to observational constraints:the quasars of the sample have bright cores and they have been targeted mainly to study the central bright source.As a result,the observation exposure times are sometimes lower than those of the RGs.The bright core is dif?-cult to model,especially if it is piled up,so that extended emission may be simply hidden,rather than nonexistent.We cannot rule out the possibility that quasars at high redshift may inhabit less rich en-vironments than radio galaxies as most of the quasars upper limits are in the low-luminosity part of the L X distribution. In the top panel of Figure2we show the distribution of the bolometric X-ray luminosity as a function of the isotropic radio luminosity as measured at178MHz.We?nd no signi?cant corre-lation between the two quantities for either the radio galaxies and the quasars. We also?nd no signi?cant correlation between the bolometric X-ray luminosity and redshift(Figure2,middle),although a peak may be present around z=0.6.To explore the evolution of the luminosity function of clusters around powerful radio-loud active galaxies it would be necessary to compare the objects drawn from this sample with objects from a broader redshift range;this would allow us to search for correlations between X-ray luminosity and redshift. We also looked for a correlation between the extent of the gas distribution and the X-ray luminosity.The full-width-half-maximum(FWHM)of theβmodel describing the intra-cluster medium(ICM)distribution is r FWHM=2r c×(0.52 8 E.Belsole et al. Table5.Physical parameters.Col.1:source3CRR name;Col.2:Central proton density;Col.3:Central pressure of the external medium;Col.4:average distance of the radio lobe from the centre of the source(and cluster).This is the distance used to calculate the external pressure at the location of the lobe;Col. 5:External pressure of the environment at the location of the lobe.This should be considered as an average value;Col.6:IC minimum(equipartition)internal pressure Col.7:IC internal pressure when it was possible to measure it from X-ray observations(see Croston et al.2005b) n0P0Rlobe P ext P min int P IC <0.6<4.38.4<3.5 3.1– 3C184 4.8+3.5 ?2.668.45+49.35 ?36.53 9.59.9+1.8 ?3.6 0.50.58±0.07 3C207 10.8+20.0 ?5.8183.0+157.0 ?85.0 12.017.6+1.8 ?1.6 0.8– 3C228 16.9+13.9 ?7.895.3+78.2 ?44.0 7.56.5+0.5 ?0.5 4.0– 3C263 6.7+13.9 ?4.025.7+53.2 ?15.2 19.50.08+0.2 ?0.05 0.80.9±0.1 3C275.1 <0.9<16.18 5.5<12.18.012.3±3.1 3C292 12.7±0.6220±10 2.0170±10100– 3C309.1 1.3+3.0 ?0.77.7+17.7 ?3.9 18.01.2+0.2 ?0.2 1.7 2.3±0.4 3C334 0.9<6.5––––3C380 2.2+0.6 ?1.345.0+13.0 ?26.0 7.513.8+2.3 ?2.1 3.3 3.7±0.6 3C 454.3 Figure3.External(cluster)pressure at a position corresponding to the av- erage distance of the radio lobe from the cluster centre versus total internal pressure calculated from an X-ray component of CMB inverse-Compton scattered emission in the lobe where measured,or the minimum pressure (Croston et al.2005b).The continuous line indicates equality between ex- ternal and internal pressure. 6THE STATE OF THE RADIO SOURCE We computed the central density,central pressure and the pressure at the location of the lobe using the best?tβmodel and the tem- perature that characterise the sources in the sample.Whenever only upper limits of the gas distribution were available,we calculated3σ upper limits for central density and pressure.We used the relation given in Birkinshaw&Worrall(1993)to derive central proton den- sity and pressure from the central count density.Results are tab- ulated in Table5.The pressure of the external environment was calculated at(or at times extrapolated to)a distance corresponding to half the distance between the centre and the edge of the radio lobe(sometimes terminating in a hot spot).This should account for the fact that radio lobes have a cylindrical shape so the pressure at the cylinder edges is a function of the gas pressure and so the distance from the centre of the cluster. The internal pressure of the radio source was calculated by combining X-ray(IC)and radio data for those sources with detected X-ray emission from the radio lobes(Croston et al. 2005b,for details).For all other sources minimum pres- sures were computed using the radio data only.The IC and minimum internal pressures were obtained using the code of Hardcastle,Birkinshaw,Worrall(1998b),using the radio and X-ray ?ux measurements,lobe volumes,and electron energy model pa- rameters for each source given in Croston et al.(2005b).For CDQs we are unable to calculate the radio source pressure as the jet dom- inates the X-ray and radio emission(see Sec.3.2)and they are thus ignored in this analysis.In Figure3we plot the external,thermal gas pressure versus the internal pressure of the radio lobes.Mini- mum pressures are treated here as lower limits.The continuous line shows the equality of internal and thermal pressure. Most of the sources appear to be close to pressure balance, with only a few exceptions.The source at the far right edge of the plot is3C184whose size is very small(only few arcsec).We have argued in Belsole et al.(2004)that the size and relative pressure of this source suggest that it may be in a young phase and beginning to expand into the external medium(see also Siemiginowska et al. (2005)for a similar conclusion about3C186).3C265also has lobes that are over-pressured with respect to the external gas.The sources that appear to have lobe pressures that are signi?cantly lower than the pressure of the ICM are3C200,3C207,3C220.1 and3C427.1.The radio lobe pressure of3C220.1is a lower limit (minimum pressure)so the real pressure can be higher and in agree- High redshift FRIIs:large-scale X-ray environment 9 ment with pressure equilibrium.3C 207has a bright core and cau-tion should apply as the measurements of external pressure may have a larger than statistical error due to additional contamination of the extended environment by the point source.The remaining sources are the two low-excitation RGs (LERG)in the sample and their lobes appear genuinely under-pressured with respect to their environments.As lobes cannot evolve to a state where they are truly underpressured,this suggests that our pressure estimates for these sources may be incorrect. Earlier evidence has suggested that LERGs prefer richer en-vironments than high-excitation objects (e.g.,Hardcastle 2004;Reynolds,Brenneman &Stocke 2005).Our result suggest that even at high redshift,powerful LERGs appear to inhabit rich en-vironments.The behaviour of their nuclei,both from an opti-cal/infrared and X-ray perspective,appears more similar to that of less powerful FRI radio galaxies,which are almost all LERGs.The X-ray properties of the cores of 3C 200and 3C 427.1(Belsole et al.2006)are de?nitively consistent with this picture. It is well known that the minimum pressures in the lobes of low-power FRI sources are almost always found to be lower,often by an order of magnitude or more,than the external pres-sures estimated by observations of hot gas (e.g.Croston et al.2003;Dunn,Fabian &Celotti 2006),requiring either signi?cant depar-tures from equipartition in the lobes or,more likely,a dominant contribution to the lobe pressure from non-radiating particles.Our results point to the intriguing possibility that some high-power LERGs may resemble low-power sources in this respect as they do in their nuclear properties.This would imply that in fact the work done by the radio source on the environment is higher than that measured from radio observations alone (i.e.minimum energy).Thus,in contrast with what we and others have found to be the case for narrow-line radio galaxies and quasars,for the two LERGs in our sample we have measurements of the IC from X-ray obser-vations (Croston et al.2005b).We still observe the sources to be over-pressured by their environments,even though the measure we have of their energy density is more realistic than minimum energy. There is evidence that some other LERG FRII sources have minimum lobe pressures that lie substantially below the exter-nal thermal pressures (e.g.3C 388,Kraft et al.2006;3C 438,Kraft et al.2007)but this is the ?rst time that we have been able to use inverse-Compton constraints to show that the radiating par-ticles and associated magnetic ?eld cannot provide the required pressures:it is most likely that the ‘missing’pressure in these two sources is provided by non-radiating particles such as protons. With only two sources we cannot make a general statement,but observations of more LERGs at relatively high redshift would be bene?cial to understand this dichotomy. 7ARE RADIO GALAXY CLUSTERS DIFFERENT FROM OTHER CLUSTERS?We have searched for any difference between X-ray clusters around radio galaxies and clusters selected with a different technique.We plot in Figure 4the luminosity-temperature relation for the objects in our sample.The dashed line shows the best-?tting correlation for an optically selected sample of clusters from Holden et al.(2002).Errors on both luminosity and temperature for the sources in our sample are large,but we do not observe a particular trend in the relation,and most of the sources appear in agreement (within the uncertainties)with the L X ?T relation valid for other clusters at the same redshift and also with the L X ?T relation of local clusters Figure 4.Luminosity-Temperature relation.The line is the best ?t for a sample of optically selected clusters at z ～0.8;from Holden et al.(2002).Symbols are as in Fig.2 (e.g.Arnaud &Evrard 1999)once the redshift dependence is taken into account.We observe that most of the quasars lie to the left of the plot.Most of the data points are upper limits,so that it is dif?cult to draw strong conclusions from this result.However,the position of the quasars may also indicate that the high brightness of these sources with respect to their temperature may be due to our detection of the central part of the cluster only.Since the nuclei of these sources are brighter than those of radio galaxies,it is possible that with the current data we are detecting only the central,denser and cooler region of a more extended cluster,i.e.the cooling core region. Contrary to expectations,we do not ?nd any source to be too hot for its luminosity.This is in contrast with results ob-tained for lower redshift radio sources,particularly in groups (e.g.,Croston et al.2005a).However the clusters we detect tend to have relatively high temperatures and thus with the statistics available for such high redshift sources it is not surprising that any possi-ble effect of heating of the ICM by the radio source is hidden or masked by the poor statistics.On the other hand,we ?nd that a few sources are overluminous for their temperature.We believe that this is more likely to be the effect of detecting only the central part of the cluster,which may be highly luminous because of its high den-sity (cooler regions).Clusters at lower redshift,for which statistics allow the separation of the cooling region,have been found to be less luminous once the effect of the cooling ?ow is corrected for (e.g.Markevitch 1998;Gitti et al.2007). 8THE ENVIRONMENTS OF HIGH-REDSHIFT SOURCES AND THE LAING-GARRINGTON EFFECT The Laing-Garrington effect (Laing 1988;Garrington et al.1988),in which the lobe with the brighter or only jet appears less de-polarized at GHz radio frequencies,has been attributed since its discovery to a ‘hot halo’around the powerful radio sources in which the effect was ?rst seen.The standard interpretation (Garrington &Conway 1991)is that the counterjet side,which in beaming models is the side further away from us,is seen through more of the hot gas in the group or cluster environment.As a result small-scale magnetic ?eld variations in the hot gas give rise to unre- 10 E.Belsole et al. solved or partially resolved(e.g.Goodlet&Kaiser2005)Faraday rotation structure and therefore‘beam depolarization’in the low-resolution images typically used to study the effect.If aβmodel describes the hot gas in the system,Garrington&Conway(1991) show that the core radius of the cluster must be comparable to the size of the radio sources(i.e.～100kpc)for a signi?cant Laing-Garrington effect to be observed.Thus observations of the Laing-Garrington effect essentially predict the existence of cluster-scale X-ray emission in the source concerned.We are now in a position to compare that prediction with the results of X-ray observations. Laing-Garrington effect detections are only possible in sources with detected kpc-scale jets,which represent only a frac-tion of the objects in our sample.Of these,not all have depolar-ization measurements in the literature.The sources with reported Laing-Garrington effect detections in our sample are3C200(Laing 1988),3C207(Garrington,Conway&Leahy1991),3C228(John-son,Leahy&Garrington1995),3C275.1(Garrington et al.1991) and3C334(Garrington et al.1991).Of these only one(3C200) has an environment with well-characterised spatial properties(Ta-ble3)but these are at least qualitatively consistent with expecta-tions:the core radius is comparable(within the large errors)with the～10arcsec lobe length.From Laing(1988),using the results of Garrington&Conway(1991),we can calculate the Faraday dis-persion,which we can compare to the simple model of Garrington &Conway(1991)using our best-?tting parameters for the3C200 environment.The ratio of the Faraday dispersions for the measured core radius requires the source to lie at a relatively large angle to the line of sight(see?gure7of Garrington&Conway1991), which seems unlikely given its very one-sided jet(e.g.Gilbert et al.2004).However,the large errors on the core radius mean that smaller angles can be accommodated by the data.Setting this aside, the best-?tting parameters for the hot gas can reproduce the lobe and counter-lobe Faraday dispersion in the Garrington&Conway model if the magnetic?eld strength in the gas is about0.5μG(0.05 nT). Faraday dispersions in the other lobes with Laing-Garrington measurements have comparable values,so we might expect roughly similar environments for these objects.The two other sources with cluster detections,3C207and3C228,both seem to reside in com-parable environments–3C207’s is rather more luminous but may well be less centrally peaked than3C200’s.However,the non-detection of environments for3C334and3C275.1is perhaps sur-prising.The spectral upper limits on the luminosities of extended emission for these sources are comparable to the detection for 3C200(Table4),so the simplest explanation is that these sources do have extended thermal emission that is just below our detection threshold.There is certainly at present no gross inconsistency be-tween the depolarization measurements and our results. 9ENTROPY PROPERTIES Entropy is an important quantity,since it allows us to investigate at the same time the shape of the underlying potential well of the clus-ter and the properties of the ICM.Entropy is generated in accretion shocks during the formation of the cluster(e.g.Tozzi&Norman 2001;V oit et al.2003;V oit2005;Borgani et al.2005),but it can be modi?ed by non-gravitational internal processes after the forma-tion of the cluster itself.Much emphasis has been placed on entropy in studies of galaxy clusters,from both a theoretical(e.g.V oit et al. 2002;V oit,Kay&Bryan2005;Muanwong,Kay&Thomas 2006,and references therein)and observational(e.g.Ponman,Sanderson&Finoguenov2003;Pratt&Arnaud2005; Piffaretti et al.2005;Pratt,Arnaud,&Pointecouteau2006)per-spective.Recent results show that entropy is higher than expected from pure gravitational models on cluster spatial scales out to at least half the virial radius(e.g.Pratt et al.2006,and ref-erences therein)and not only in the central regions.Although the pre-heating scenario(e.g.,Kaiser1991;Evrard&Henry 1991;Valageas&Silk1999)is now considered unlikely(e.g. Ponman et al.2003;Pratt&Arnaud2003,2005),mechanisms such as heating and cooling due to more recent supernovae or AGN activity are still a viable explanation for the general excess of en-tropy.There is a consensus about the signi?cant effect of feedback from a central AGN in the evolution of the ICM.An important result is that central AGNs can act not only in the central region of what were historically called“cooling?ow”clusters,but also on large scales,e.g.through sonic shocks,observed as ripples in the ICM(Fabian et al.2006)or strong shock waves(Forman et al. 2005).This is particularly relevant as the AGN hypothesis to explain the excess entropy in galaxy clusters can also apply to the large scale excess and it is not limited to the central entropy excess initially detected in cool systems(e.g.Ponman,Cannon&Navarro 1999;Lloyd-Davies,Ponman&Cannon2000; Ponman,Sanderson&Finoguenov2003). These recent results on entropy motivated us to investigate the entropy properties of the clusters in our sample.Although the errors are large,this is the?rst time that entropy has been investigated for the ICM around radio sources at this redshift.Here we adopt the accepted de?nition of entropy in the X-ray: S=kT/n2/3 e (3) In order to compare with low-redshift clusters,we scale this with redshift using the relation S z=h4/3(z)×S.For the sources in the sample we are unable to produce entropy pro?les as we only have a global temperature and therefore the shape of the pro?le would depend exclusively on the shape of the density pro?le.We thus only obtained global entropy properties at speci?c distances from the centre of the cluster. Figure5,left,shows the central entropy S0compared to the radio power at178MHz.The isotropic radio power is often taken to be a proxy of the jet power(Willott et al.1999),and thus should be correlated with the power being injected into the ICM.The entropy re?ects the accretion history of the cluster but also the in?uence of non-gravitational processes.We?nd that the central entropies of all the objects in the sample are similar and there is no correlation between S0and L178MHz.We also see that RGs and quasars are scattered equally in the space de?ned by these two parameters,al-though caution should be used as regards the CDQs since their low-frequency radio emission may be contaminated by emission from the jet.The lack of correlation between the two quantities may be the result of the short life time of the radio source with respect to the cluster age;the two quantities may be unrelated because they arise from processes that take place at different epochs. In the right-hand panel of Figure5we plot the entropy at0.1 r200versus the temperature of each cluster(upper limits are not shown for clarity,but symbols without error bars should be in-terpreted as limits).This is similar to what Pratt et al.(2006)and others have done for lower redshift clusters.In the Figure the ob-jects in our sample are compared to a sample of10clusters at red-shift less than0.2(Pratt et al.2006).We also plot the best-?tting temperature-entropy relation for this low-z cluster sample,extrap-olated to low temperatures.We observe that,at0.1r200,clusters around RGs with temperature above2.5keV appear similar in their High redshift FRIIs:large-scale X-ray environment 11 Figure5.Left:Central entropy versus the radio power of the source at178MHz.We used the best-?tting temperature when available and otherwise took a?xed value when the data were not of good enough quality to perform spectral?tting.Right:Entropy calculated at0.1r200as a function of the cluster temperature.Errors are not shown when the temperature used to?t the spectrum was a?xed parameter.(The only exception is for3C309.1,where the arrow does not represent a limit but is used to show that the lower boundary of temperature error is beyond the scale of the plot.)The red diamonds are clusters at redshift<0.1and with temperatures between2.9and10keV,from Pratt et al.(2006).The dashed line is the best?t to the cluster sample only,extrapolated to low energy.In the centre and bottom?gure the entropy S has been scaled for redshift as S z=h(z)4/3×S,where h(z)=(?m×(1+z)3+?Λ)0.5 entropy properties,within the uncertainties,to clusters at lower red- shift.However they are preferentially found above the best-?tting temperature-entropy relation for local clusters,suggesting that they have a larger amount of entropy than their local counterpart.The cooler radio-galaxy clusters all lie below the local S?T relation of Pratt et al.,and although we do not show it here,our data can- not be?tted by the best-?t S?T relation of slope0.65found by Ponman et al.(2003)using a sample of local groups,galaxies and clusters,which may be a more appropriate comparison for the low- temperature systems in our sample.We have calculated the entropy at0.5r200and the trend is similar.However,in many cases calcula- tion of the density at this radius requires a large extrapolation from the data so that the results may be biased. Using the ASURV package(Isobe et al.1990)to account for censored data,we?nd that the relationship between S(0.1r200) and T is?tted by a relation of slope1.32±0.22,in reasonable agreement with what is expected from self-similar models(slope of 1;Ponman et al.1999)–note that errors here are1σ.This seems to suggest that there is less entropy in high-redshift cool systems than their local counterparts,which is the opposite of what is expected if,as observed for larger sample of galaxy groups and clusters,the cool systems are more strongly affected by feedback processes.It also appears counter-intuitive given the presence of a powerful ra- dio source at the centre of all our clusters.However,the presence of the radio source may represent a concrete explanation for this behaviour.The AGN(at least for the conventional AGN that dom- inates our sample)needs to be fuelled to be activated and for the accretion to be radiatively ef?cient,as is the case for most of the sources in the sample(see Belsole et al.2006),it needs the accreted gas to be relatively cold.The required cool gas becomes available when low-entropy gas is present close enough to the accretion re- gion.For this to happen,it is commonly accepted that the cluster must be in a virialized state.Since the cluster requires a time which is much longer than the lifetime of synchrotron emitting electrons at1.4GHz(～108yrs)to relax,the radio sources in this sample may be in a state in which the energy of the outburst due to the AGN activation has not yet been transferred to the ICM,even in the cen- tral region.Clusters at lower redshift,such as those in Pratt et al. (2006)or groups(Ponman et al.2003)have had more time for the distribution of AGN energy output throughout the cluster,and their high entropy level,especially within0.1r200,may be the effect of repeated outburst.If we accept the interpretation of cyclic activa- tion of the central supermassive black hole,the duty cycle must be higher in low-redshift clusters.It is possible in our present sample that we are witnessing the?rst activation of a radio galaxy at the centre of a dense cluster-like environment,particularly bearing in mind that the3CRR sources on which our sample is based are at the top end of the luminosity function and are rare at all epochs. This may also be interpreted as suggesting that the duty cycle of more luminous radio sources is much lower than that of less active AGN.In other words,the sources in the sample with low central entropy may be selected to be those in which the effect of the radio source is not yet observable in entropy,but will be in the future. If this result can be con?rmed with better statistics,and/or the larger samples that will be available with X-ray instruments such as XEUS,it may give important constraints on the overall mecha- nism of AGN heating of the ICM,entropy distribution in large scale structure and,last but not least,the formation,evolution and ageing of radio sources in dense environments. 10CONCLUSIONS We have analysed X-ray data from Chandra and XMM-Newton of 20powerful RGs and quasars at redshift0.45 aim of investigating their external environment and its interaction with the bright radio source.We?nd that: (i)RGs and quasars inhabit a range of environments without any obvious relationship to radio properties such as radio power and size. (ii)more than60per cent of the sources lie in X-ray emitting environments of luminosity greater than1044erg s?1.The poorest environments in this redshift range are consistent with moderate- 12 E.Belsole et al. luminosity groups(L X～1042erg s?1),the richest with Abell class2(L X>5×1044erg s?1))or above clusters. (iii)Our results are in agreement with uni?cation schemes that predict that the environment of sources oriented with various angles to the line of site should be isotropic.Most of the objects whose jet is oriented close to the plane of the sky(RGs)are detected to lie in rich environments while for6out of9quasars we are able to estimate upper limits for the existence of a cluster-like component around them.These upper limits occupy the same parameter space of luminosities as the detected sources.Seven of the sources are found to be point-like.However three of them are core-dominated quasars for which the detection of a low-surface brightness X-ray component is hampered by the the bright X-ray core emission. (iv)Within the uncertainties,these are normal environments, with no evidence that they deviate from the temperature/luminosity relationship observed in low-z normal clusters.Therefore there is no strong evidence that the presence of a radio source requires a peculiar environment or strongly affects the cluster.This may also suggest that deviation from self similarity and the scatter around scaling laws is likely to be affected by other processes such as mergers(Maughan2007),rather than the interaction between the radio source and the central cluster. (v)For the?rst time for radio active sources at this redshift we investigate the entropy of the ICM.To our surprise we?nd that the entropy/temperature relation is steeper than that observed for low-redshift normal galaxy clusters,and closer to the relation predicted by self-similar models.We argue that this is the result of processes occurring at different epochs,the intensity of the AGN duty cycle at low and high redshift,and that the heating from the radio source outburst may have not have had the time yet to be observed in the ICM entropy for sources at redshift above0.5. (vi)Most of the sources appear close to pressure balance with the cluster,with the exception of the two LERGs in the sample which appear under-pressured.Although measurements of the in-ternal pressure are still uncertain,this comparison is more precise than using simple minimum pressures from radio data.The re-sult on LERGs may be the?rst evidence of the presence of non-radiating particles that contribute to the radio source internal pres-sure in powerful radio sources. APPENDIX A:NOTES ON INDIVIDUAL SOURCES In this Appendix we describe details of the source-speci?c anal-ysis for each of the sources in the sample.For each source we show wavelet-decomposed images in the soft(0.5-2.0keV)and hard(2.5-7.0keV)energy bands,together with the radial pro?le ?tting described in the text,with both a PSF alone and a PSF plus β-model when required.The?tting results for radial pro?le and spectral analysis are in Tables3and 4.The images and pro?le can be inspected in Fig.A1-A18.The contours in the images are from VLA data at1.4GHz,except where otherwise stated.No ra-dio overlays are shown for the4CDQs due to the small size of the source(see also Sec.3.2). ?3C6.1:The radial pro?le is well?tted with a PSF only and there is no signi?cant improvement in the?t if an extra component is added.We?x theβparameter to0.5and the core radius r c to15 arcsec=115kpc,for a2keV cluster,which is a typical r c value for a cluster in the local universe(～125kpc).We calculate a3σupper limit for any cluster-like extended emission with these parameters. We extracted the spectrum in the same source and background area as used for the radial pro?le.We?tted the spectrum with1)a power law absorbed by Galactic absorption and2)a thermal model. We?nd a similar goodness of?t.The power-law slope is found to be1.7±0.5when the spectrum is?tted between0.5-2.5keV and 1.4±0.23if the0.5-6.0keV band is used.Both are consistent with the spectrum being due to the wings of the PSF.However,the number of counts does not correspond to what is expected from the wings of the PSF at the distance from the centre we use(a circle of radius5-arcsec was used to mask the central unresolved point source).The source is only slightly piled-up.The other option for the nature of this extended emission may be IC from the region coincident with the radio lobes or the hotspots.However those ar-eas were masked prior to spectrum extraction,and Croston et al. (2005b)?nd only upper limits for the IC emission from the lobes. For this reason,we evaluated the luminosity of the emission de-tected in the circle of radius49.2arcsec used for the spectral analy-sis by?xing a temperature of2keV and assuming it to be thermal. Images of3C6.1are in Figure A1. ?3C184This source was analysed in detail by Belsole et al. (2004).The point source is not spatially separated from the ex-tended emission with the XMM-Newton data,and20ks are not suf?cient to detect cluster emission with Chandra.However,the XMM-Newton spectrum is best?tted with3components,one of which is a MEKAL with at best-?t temperature of～3.6keV.Images and pro?les can be inspected in Belsole et al.(2004). ?3C200:This is a low-excitation radio galaxy,so the core is faint with respect to the lobe emission,making the investigation of diffuse emission easier.The statistics are good enough to constrain the radial pro?le and spectral parameters.Figure A2shows images for this source. ?3C207:There are a total of190net counts in the region used for the spectral analysis:a circle of radius15arcsec with the ex-clusion of a circle of radius5arcsec to mask the core,and areas to mask the western lobe and jet.The spectrum can be?tted with a simple power-law model of slope1.15,giving aχ2/d.o.f=3.06/4. There is no statistically signi?cant need for a thermal component in agreement with Brunetti et al.(2002)and Gambill et al.(2003). However,the radial pro?le analysis strongly suggests the presence of an extended component with a King pro?le distribution and stan-dard parameters.We thus calculated the fraction of counts from the wings of the PSF expected in the area used for the spectral anal-ysis,and we derived the normalisation of the power law model in this area.We then?xed the value ofΓto be equal to the lower limit ofΓfound while?tting the core spectrum.This is justi?ed by the ?attening of a point source spectrum in the PSF wings.Finally we assumed that the rest of the counts were from extended,cluster-like emission that was?tted with a MEKAL model of?xed temperature 5keV.Given the uncertainties of the spectral?tting,we have as-signed the source a quality?ag of D(detection only)despite the fact thatβmodel parameter are well constrained.These results should thus only be regarded as giving one plausible https://www.doczj.com/doc/4c11868683.html,ing the same data Brunetti et al.(2002)interpret most of the X-ray emis-sion surrounding one of the lobes as non-thermal;however,they do not exclude the possibility that a low-surface brightness cluster may be present. ?3C220.1:This source was detected previously with ROSAT (Hardcastle,Lawrence,Worrall1998a)and using the same Chan-dra data by Worrall et al.(2001).It is one of the best examples of a rich cluster around a radio galaxy in this redshift range,and the precision of physical parameters obtained from spatial and spectral analysis are comparable to X-ray clusters in the local universe.Our results are in perfect agreement with previous studies of this cluster. ?3C228:Two exposures for this source give a total of～24ks High redshift FRIIs:large-scale X-ray environment13 Figure A1.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C6.1.Contours are from a1.4-GHz radio map(A con?guration,L band)and are logarithmically spaced.Radial pro?le?tted with a simple PSF.Theβ-model?tting of the radial pro?le is not shown as only an upper limit was calculated. Figure A2.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C200.Contours are from a1.4-GHz radio map(B con?guration,L band)and are logarithmically spaced.Radial pro?le?tted with simple PSF and a PSF plus aβ-model. of?are-clean Chandra observation.This allows us to explore the β-r c parameter space but not to constrain the two parameters.The point source dominates the X-ray emission out to6arcsec and this was excluded prior to spectrum extraction.We thus?xed theβand r c to0.5and15arcsec respectively and only calculated errors on the normalisation. The spectrum is well?tted with a MEKAL model of kT=3.9 keV and metallicity0.3solar.However it can also be?tted with a power law ofΓ=1.8.The two?tted models are statistically equivalent;however,the nucleus of the source has a?atter(Γ= 1.6±0.1)spectrum,so that this emission is unlikely to come from the wings of the PSF.IC emission from the radio lobes may be the other source of uncertainty but Croston et al.(2005b)only?nd upper limits on IC?ux from the radio lobes.We thus assume that a thermal model describing the external environment is the most likely interpretation for the X-ray emission detected by our spectral analysis. ?3C254:The radial pro?le of3C254is dominated by the PSF out to40arcsec.This is one of the signi?cantly piled up sources, with a pileup fraction of20per cent.However,for both the radial pro?le and the spectral analysis,the PSF alone is not suf?cient to account for all the X-ray emission and we constrain the shape(βmodel)and spectral parameters.From the best?t r c value the object appears rather compact and the low temperature we?nd may sug-gest that we have possibly detected the galaxy atmosphere rather than a cluster.Crawford&Fabian(2003)detect extended X-ray emission around3C254with a luminosity in the0.5-7keV range of(3.1±1.2)×1043erg s?1,which is in agreement with what we ?nd within the errors. ?3C263:The source is heavily piled up.We used the piled up PSF model to characterise the point source distribution.However, given the uncertainties of this model for heavily piled up sources, we cannot account for all the residuals and the?t is not good.The addition of aβ-model improves the?t but the parameters we?nd are not physical,and suggest a best-?t value for the core radius close to zero.We interpret this result as the effect of our poor mod-elling of the wings of the PSF for a heavily piled up source.As a result,we?xβand r c to canonical values and obtained upper limit only from both the radial pro?le and spectrum. Crawford&Fabian(2003)and Hardcastle et al.(2002)previ-ously studied this source and they both claimed detection of cluster emission,albeit of low surface brightness.However their modelling of the PSF did not take pileup into account and their result may be due to pollution from the point source,although3C263seems to lie in a spectroscopically con?rmed optical cluster(Hall et al. 1995).To summarize,it may be possible that a cluster exists around 3C263,but given the poor?tting results we obtain we adopt the safe solution and use upper limits only for this source. ?3C265:The upper value of theβparameter was not con-strained,which can be explained as the result of the poor statistics for this object,mostly due to the large mask used to exclude the radio lobes.The relatively low temperature we measure suggests that the source lies in a group or that we are detecting only the very centre of a larger cluster which may have a cool core. ?3C275.1The radial pro?le and the spectral analysis both in-dicate that the X-ray emission is from a point source.We thus carried out upper limit calculation for the existence of a clus-ter component.This is not in agreement with what was found by Crawford&Fabian(2003)who detected a cluster of bolometric X-ray luminosity7.6±0.9×1043erg s?1. ?3C280:Theβ-model parameters are not constrained.How-ever,there is a signi?cant improvement over a PSF model alone if an extended model is added.We use here the best-?tting parame-ters of theβmodel to characterise the extended emission:the de-rived values should therefore be used with caution.Similarly,the count statistics of the current Chandra observation do not allow us to constrain the temperature,although the spectrum is better?tted with a thermal model than a power law.The luminosity we mea-sure is within the upper limit of Donahue,Daly&Horner(2003), although we claim a detection. ?3C292:Belsole et al.(2004)give a detailed analysis of this source. ?3C295:This rich cluster was previously studied by Allen et al.(2001)using a Chandra ACIS-S observation.We have used a more recent90-ks observation made with the ACIS-I detec-tor.These data have extremely good statistics and would allow a much more detailed analysis of the source than we have presented here.For consistency,however,we have analysed3C295in the same way as all the other sources.The host cluster of3C295is the most luminous cluster around a3CRR source in the redshift range of the paper.Our morphological analysis agrees with what was found by Allen et al.Since we calculate a global temperature for the cluster,we?nd a slightly lower temperature than Allen et al.,who exclude the cooling?ow region.For the same reason, 3C295appears too luminous for its temperature(see Fig.4).How-ever,if we accept the measurements of Allen et al.beyond50kpc, the source is found more in line with the L X?T relation shown in Fig.4.Despite being an extreme case in our sample(because of the number of X-ray counts detected and high luminosity),3C295 appears similar to the other3CRR sources in the0.45–1redshift range when its global properties are considered. ?3C309.1:This is the only core-dominated quasar for which we have been able to estimate the extent of the thermal emission. The source was observed with a small window and thus only the area covered by the detector was used.A King pro?le in addition to the PSF is required to?t the radial pro?le of3C309.1,and the shape of the pro?le is constrained.In order to increase the S/N ra-tio we reduced the area for extraction of the spectrum to a circle of radius32arcsec(instead of r=～40arcsec used for the radial pro?le).The bright point source was masked by a circle of radius 9arcsec,thus reducing considerably the contamination of the PSF, even for a piled up source.The readout streak was also masked. The low number of counts in this region(60net counts)requires the use of Cash statistics.Although a power law gives an accept- 14 E.Belsole et al. Figure A3.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C207.Contours are from a1.4-GHz radio map(A con?guration,L band)and are logarithmically spaced.Radial pro?le?tted with simple PSF and a PSF plusβ-model. Figure A4.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C220.1.Contours are from a1.4-GHz radio map(B con?guration,L band)and are logarithmically spaced.Radial pro?le?tted withe simple PSF and a PSF plusβ-model. able?t for the spectrum,the slope is too steep(Γ=2),and it is not in agreement with the spectrum of the point source.The spectrum of3C309.1is better?t with a MEKAL model of low temperature ～0.9keV,even though the statistical errors are large.Therefore, spatial and spectral data both seem to indicate that this object lies in a X-ray emitting external environment.With the current data we cannot say whether our detection corresponds to a galaxy group, a bright elliptical galaxy or the centre of a cooling core cluster at-mosphere and additional observations of this source would help to shed light on the nature of its environment. ?3C330:The Chandra data allow us to fully determine the spa-tial and spectral characteristics of this source.Our results are in agreement with those of Hardcastle et al.(2002). ?3C334:The radial pro?le is well modelled with a PSF ac-counting for pileup.The spectral distribution suggests that if a ther-mal component is present,it is relatively cold as the20net counts left after excluding the core emission are below1keV.We thus ?xed the temperature to be1keV and calculated a3σlimit for the presence of an extended environment. ?3C345:The radial pro?le is modelled with a PSF,accounting for pileup.We?x the temperature of any thermal component to 2keV to estimate the upper limit of thermal emission from the spectrum. ?3C380:Like3C345,3C380is a core-dominated quasar for which the modelling of the PSF is complicated by pileup.The ra-dial pro?le is well?tted with a PSF model and upper limits are evaluated for the existence of an extended thermal component us-ing our standard values forβand r c and assuming a temperature of 2keV. ?3C427.1:This source is a LERG with a very weak nucleus. The emission extends out to a radius of200kpc and is thermal in nature,with a best-?t temperature https://www.doczj.com/doc/4c11868683.html,ing the radial pro?le we can only map the extended emission out to25per cent of the virial radius and there may be some indication that a sec-ondaryβmodel is needed to?t the pro?le,but its parameters are not constrained.Croston et al.(2005b)did not detect signi?cant counts from the radio lobes.Nevertheless,we applied a conservative ap-proach and excluded the spatial areas coincident with the radio lobes when extracting both spectrum and radial pro?le.The ther-mal model?t gives an interestingly high temperature for a source at this redshift.The Fe Kαline appear very strong.If the chemi-cal abundance is left as a free parameter,the best?t give Z/Z⊙= 1.68,and1σerrors suggest that it is a greater than0.76(although the upper limit is found to be3.8.We thus decided to?x Z/Z⊙to1and?t with this parameter frozen.A power-law model gives a worse?t but not signi?cantly so(?χ2=2.5)and a best?t of Γ=1.6±0.2. ?3C454.3:Even though the radial-pro?le?t using a piled-up PSF shows signi?cant residuals,we interpret this as the effect of a poor modelling of the pileup rather than the detection of a sec-ondary component.As a result,for this core-dominated quasar we calculate3σupper limits for the presence of an extended and ther-mal(1keV)environment.ACKNOWLEDGEMENTS We are grateful to Gabriel W.Pratt for enlightening discussion about entropy and to Alexey Vikhlinin for providing his wavelet algorithm.We thank the anonymous referee for useful and de-tailed comments that improved the manuscript.E.B.thanks PPARC for support and MJH thanks the Royal Society for a research fel-lowship.This work is partly based on observations obtained with XMM-Newton,an ESA science mission with instruments and con-tributions directly funded by ESA Member States and NASA.This research has made use of the SIMBAD database,operated at CDS, Strasbourg,France,and the NASA/IPAC Extragalactic Database (NED)which is operated by the Jet Propulsion Laboratory,Cal-ifornia Institute of Technology,under contract with the National Aeronautics and Space Administration. 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Figure A10.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C280.Contours are from a1.4-GHz radio map(A con?guration),and are logarithmically spaced.The radial pro?le is?tted with a simple PSF and a PSF plusβ-model. Figure A11.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C295.Contours are from an8.6-GHz radio map (A con?guration),and are logarithmically spaced.The radial pro?le is?tted with a simple PSF and a PSF plusβ-model. Figure A12.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C309.1.Radial pro?le?tted with a simple PSF and a PSF plusβ-model. Figure A13.From left to right:Soft(0.5-2.0keV)and hard(2.5-7.0keV)wavelet-decomposed image for3C330.Contours are from a VLA1.4-GHz radio map taken in con?guration A,and are logarithmically spaced.Radial pro?le?tted with a simple PSF and a PSF plusβ-model. 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R.,2001,MNRAS,326,1127 Zirbel,E.,L.,1997,ApJ,476,489 This figure "Appendix-F1.jpg" is available in "jpg" format from: https://www.doczj.com/doc/4c11868683.html,/ps/0709.3635v1 This figure "Appendix-F2.jpg" is available in "jpg" format from: https://www.doczj.com/doc/4c11868683.html,/ps/0709.3635v1 This figure "Appendix-F3.jpg" is available in "jpg" format from: https://www.doczj.com/doc/4c11868683.html,/ps/0709.3635v1 This figure "Appendix-F4.jpg" is available in "jpg" format from: https://www.doczj.com/doc/4c11868683.html,/ps/0709.3635v1 实验二 Socket下的点对点通信的实现 一、实验目的 理解Socket的基本概念工作原理，掌握Socket的建立、监听、连接、发送数据和接收数据。 二、实验内容 采用Java(c++)语言编写网络上的点对点的Socket程序。该程序必须能在服务器端实现监听连接请求，客户端实现发送连接请求的功能，在建立连接后进行发送和接收数据的功能。三、实验要求 实验课时为4学时。要求完成在服务器端和客户端的源程序的编写，并作出分析。 具体要求如下： 1、服务器端建立一个Socket，设置好本机的IP和监听的端口与Socket进行绑定，开始监听连接请求，当接收到连接请求后，发出确认，同客户端建立连接，开始与客户端进行通信。 2、客户端建立一个Socket，设置好服务器端的IP和提供服务的端口，发出连接请求，在收到服务器的确认后，建立连接，开始与服务器端进行通信。 3、服务器端和客户端的连接及它们之间的数据传送均采用同步方式。 socket 的基本概念 网络上的两个程序通过一个双向的通信连接实现数据的交换，这个双向连路的一端成为一个Socket。Socket通常用来实现客户方和服务方的连接。它既可以接受请求，也可以发送请求，利用它可以较为方便的编写网络上数据的传递。在Java等语言中，有专门的Socket类来处理用户的请求和响应。利用Socket类的方法，就可以实现两台计算机之间的通讯。 Host A上的程序A将一段信息写入Socket中，Socket的内容被Host A的网络管理软件访问，并将这段信息通过Host A 的网络接口卡发送到Host B，Host B的网络接口卡接收到这段信息后，传送给Host B的网络管理软件，网络管理软件将这段信息保存在Host B的Socket中，然后程序B才能在Socket中阅读这段信息。 假设第二个程序被加入图1的网络的Host B中，那么由Host A传来的信息如何能被正确的传给程序B而不是传给新加入的程序呢？这是因为每一个基于TCP/IP网络通讯的程序都被赋予了唯一的端口和端口号，端口是一个信息缓冲区，用于保留Socket中的输入/输出信息，端口号是一个16位无符号整数，范围是0-65535，以区别主机上的每一个程序，低于256的端口号保留给标准应用程序，比如pop3的端口号就是110，每一个套接字都组合进了IP地址、端口、端口号，这样形成的整体就可以区别每一个套接字。 无论一个socket通信的功能多么齐全，程序多么复杂，其 基本结构都是一样的，都包括以下四个步骤： 1、创建socket； 2、打开连接到socket的输入输出流； 3、按照一定的协议对socket进行读写操作； 《网络编程技术》 课程设计报告 课程设计题目：局域网点对点通信软件与实现作者所在系部：计算机科学与工程系 作者所在专业：网络工程 作者所在班级： 作者姓名： 作者学号： 指导教师姓名： 完成时间： 2013年07月10日 课程设计任务书 摘要 所谓网络中的点对点通信是实现网络上不同计算机之间，不经过任何中继设备而直接交换数据或服务的一种技术。由于允许网络中任何一台计算机可以直接连到网络中的其他计算机，并与之进行数据交换，这样既可以消除中间环节，也使得网络上的沟通变的更加容易、更加直接。本文介绍的是一种是用Winsock编程技术，基于TCP/IP协议的、面向连接的流式套接字网络通信编程设计。 局域网即时通讯软件使用TCP协议作为传输层的协议，采用点对点模式服务，不需要服务器支持，使局域网用户的使用更加方便和高效。它可以实现局域网用户的自动检测，用户间文本信息的交流，文件的传输等功能。 本系统使用Visual Studio 2010作为开发工具，将.NET中的一些技术运用到系统中关键词：点对点；TCP/IP；Socket；UDP；P2P 目录 摘要 (2) 目录 (3) 第1章绪论 (4) 1.1课题研究现状分析 (4) 1.2选题的目的及意义 (4) 第2章系统需求分析 (5) 2.1 问题的提出 (5) 2.2 系统的设计目标 (5) 第3章系统总体设计 (6) 3.1系统功能设计 (6) 3.2功能模块的说明 (7) 3.2.1初始化（广播用户信息） (7) 3.2.2用户列表管理 (7) 3.2.3文本信息传输 (7) 3.2.4文件传输 (7) 3.2.5发送心跳包 (7) 第4章系统实现 (8) 4.1初始化模块的设计和实现 (8) 4.1.1监听端口 (8) 4.2 广播消息 (8) 4.3 文本消息的发送和接收 (9) 4.4 文件的发送和接收 (12) 4.5发送心跳包 (14) 第5章课程设计总结 (16) 5.1 主要问题及解决办法 (16) 5.2 课程设计体会 (16) 5.3 自我评定 (16) 参考文献 (17) 听《多点对多点通信》讲座有感之《点对点和点对多点语音通信的应用》 PoC将直接的点对点和点对多点语音通信业务引入到蜂窝网络中，使流行的半双工无线业务在蜂窝手机中得以应用，这将为运营商带来更多的注册新用户，同时增加ARPU。 多样化平台 该业务的原理其实比较简单，我们称之为“JustPushtoTalk”，这得益于“always-on”连接，IP技术正是实现该连接的根本。正是这个特点，呼叫可以仅仅通过按一个键，而且不管是在点对点用户中还是在通话群组中，在相对较短的时间内建立连接。PoC业务并不替代现已存在的蜂窝业务，不用改变传统的语音业务。建立在半双工VoIP基础上的PoC解决方案，构建在当前GSM/GPRS网络上，保护了投资，并能平滑过渡到3G，PoC业务同样可以看作为IMS(3GR5以上内容)前期服务。面向电路交换的移动网络，在用户通话之前必须通过拨号进行呼叫建立过程，这一点与“always-on”连接截然不同。在用户通话过程中，面向电路交换的呼叫始终占据上行和下行两个方向的资源；而基于半双工的PoC业务，只在有通话过程中占用资源，通话结束立即释放，所以能大量节省资源。 OMA对PoC统一地进行了标准化工作，以保证其互连互通性，提供一个能开展多媒体应用的业务平台。烽火移动公司结合OMA标准，根据对PoC的深入研究和理解，并提出了基于OMA的PoC构架模型。 新的突破 烽火移动公司已经在由我国自主知识产权的国际通讯标准———TD-SCDMA 上对PoC业助，緯累了一定的研究抐果，具备了相容完备的圬TD-SCDMA网络上宾瞐PoC业务的技术和概念。 基于OMA标准揑出的PoC构架，烽火移动公司提出亄TD-SCDOA网络中PoC 业务的具体实现方案。该方案将PoC服务器放在运营商IP网络中?SI?CORE 在TD-S?DMA穑络IMS域的CSCF中实现。PoC业务(包括语音、数字，以及将潥的视频等)?据均由TD-SCD?A的分?业务传送方式提供：语音采用BTP/IP支持的VoIP方式提供，使用AMR编码(比?：5.15kb?t/s)，能提高字节和帧的容错 基于STC89C51的CAN总线点对点通信模块设计 [导读]随着人们对总线对总线各方面要求的不断提高，总线上的系统数量越来越多，继而出现电路的复杂性提高、可靠性下降、成本增加等问题。为解决上述问题，文中阐述了基于SJAl000的CAN总线通信模块的实现方法，该方法以PCA82C250作为通信模块的总线收发器，以SITA-l000作为网络控制器。并以STCSTC89C5l单片机来完成基于STC89C5l的CAN通信硬件设计。文章还就平台的初始化、模块的发送和接收进行了设计和分析。通过测试分析证明，该系统可以达到CAN的通信要求，整个系统具有较高的实用性。 0 引言 现场总线是应用在生产最底层的一种总线型拓扑网络，是可用做现场控制系统直接与所有受控设备节点串行相连的通信网络。在工业自动化方面，其控制的现场范围可以从一台家电设备到一个车间、一个工厂。一般情况下，受控设备和网络所处的环境可能很特殊，对信号的干扰往往也是多方面的。但要求控制则必须实时性很强，这就决定了现场总线有别于一般的网络特点。此外，由于现场总线的设备通常是标准化和功能模块化，因而还具有设计简单、易于重构等特点。 1 CAN总线概述 CAN （Controller Area Network）即控制器局域网络，最初是由德国Bosch公司为汽车检测和控制系统而设计的。与一般的通信总线相比，CAN总线的数据通信具有突出的可靠性、实时性和灵活性。其良好的性能及独特的设计，使CAN总线越来越受到人们的重视。由于CAN总线本身的特点，其应用范围目前已不再局限于汽车行业，而向自动控制、航空航天、航海、过程工业、机械工业、纺织机械、农用机械、机器人、数控机床、医疗器械及传感器等领域发展。目前，CAN已经形成国际标准，并已被公认为几种最有前途的现场总线之一。它的直线通信距离最大可以达到l Mbps／30m．其它的节点数目取决于总线驱动电路，目前可以达到110个。 2 CAN系统硬件设计 图1所示是基于CAN2．0B协议的CAN系统硬件框图，该系统包括电源模块、MCU部分、CAN控制器、光电耦合器、CAN收发器和RS232接口。硬件系统MCU采用STC89C5l，CAN控制器采用SJAl000，CAN收发器采用PCA82C250，光耦隔离采用6N137。 大学世界史重大事件时间表（完整版）适用于大学、高中、初中生 世界历史大事年表 大约三百万年前地球上出现人类 公元前3100年左右埃及形成统一的奴隶制国家 公元前3000年左右 两河流域出现奴隶制城市国家 公元前3000年代中期印度河流域哈拉帕文化 公元前2100年左右 埃及奴隶河贫民大起义 公元前1894年古巴比伦王国建立 公元前1000年左右努比亚建立奴隶制国家 公元前594年雅典的梭伦改革 公元前六世纪居鲁士统一波斯，佛教在印度产生 公元前539年 波斯占领巴比伦 公元前525年波斯灭埃及 公元前509年罗马成立贵族专政的奴隶制共和国 公元前330年波斯被马其顿灭亡 公元前三世纪摩揭陀国统一印度大部分地区 公元前73-71年 斯巴达克起义 公元前27年屋大维建立罗马的元首制，共和国转为帝国公元前后朝鲜半岛出现高句丽奴隶制国家 公元初东非阿克苏姆奴隶制国家兴起 公元一世纪基督教产生 公元三世纪日本大和奴隶制国家兴起 313年基督教在罗马取得合法地位 四世纪北非发生“阿哥尼斯特”运动 378年 西哥特人在阿德里亚堡击败罗马军队 395年罗马分裂为东西两部 410年西哥特人一度占领罗马 476年西罗马帝国灭亡，西欧奴隶制度崩溃 六世纪初法兰克王国建立 622年 穆罕默德从麦加出走麦地拉，伊斯兰教纪元 八世纪中叶阿拉伯帝国形成 646年日本大化改新 676年 新罗统一朝鲜 九世纪早期英吉利王国形成 843年查里曼帝国分裂，法兰西、德意志、意大利雏形产生九世纪封建制度在西欧确立 962年神圣罗马帝国建立 1054年基督教会分裂 1066年 法国诺曼底公爵征服英国 十一世纪中叶加纳王国全盛时期 1192年日本幕府政治建立 十三世纪 埃塞俄比亚封建国家兴起 十四世纪马里王国全盛时期，意大利出现资本主义萌芽 十四至十六世纪欧洲文艺复兴运动 1337年英法百年战争开始 1358年法国农民起义 1381年英国瓦特。泰勒起义 1453年东罗马帝国灭亡，英法百年战争结束 十五世纪桑海兴起 十五世纪晚期 英法中央集权国家形成，圈地运动开始 1480年俄罗斯摆脱蒙古控制 1487年迪亚士到达好望角 1492年哥伦布初次航行到美洲 1497-1498年达加马开辟西欧到印度的新航路 1517年 马丁。路德发动宗教改革 1519-1522年麦哲伦船队环航地球 十六世纪 葡萄牙和西班牙殖民者在亚、美强占殖民地 1524-1525 德意志农民起义 1588年 英国海军击败西班牙“无敌舰队” 1592-1598年朝鲜军民抗击日本侵略的卫国战争 1600年 英国东印度公司建立 十七世纪初法国殖民者开始在北美拓殖 1607年英国殖民者开始在北美拓殖 1632年沙俄在西伯利亚修建侵略扩张的基地—雅库次克1640年英国资产阶级革命开始 1649年 英国王查理一世被处死 1660年英国斯图亚特王朝复辟 1688年英国政变，资产阶级和新贵族的统治确立 1689年中俄签定“尼布楚条约” 通信原理三级项目 班级：姓名： 学号： 指导教师： 教务处 远距离点对点数字通信系统设计 （燕山大学信息科学与工程学院） 摘要：本文讨论进行了远距离点对点数字通信系统的设计，着重讨论了模拟信号数字化的过程，其中包含了为了提高系统性能进行的信源编码技术和信道编码技术，我采用了HDB3码克服连0问题，利用奇偶监督码和差错重传机制控制误码率。另外，讨论了数字调制技术的实现，本文采用最小频移键控调制和解调技术，并讨论了在高斯白噪声信道条件下的此方法的可靠性和有效性。 关键词：脉冲编码调制，HDB3码，奇偶监督码，MSK调制，高斯白噪声，MATLAB仿真 目录 1.通信系统概述 (3) 1.1一般通信系统模型 (3) 1.2数字通信系统模型 (3) 1.3远距离语音通信系统 (4) 2.信号数字化 (4) 2.1信号的抽样 (4) 2.1.1抽样定理 (4) 2.1.2脉冲幅度调制PAM (5) 2.2信源编码 (6) 2.2.1十三折线法 (6) 2.2.2脉冲编码调制PCM (7) 2.3信道编码 (9) 2.3.1 HDB3码 (9) 2.3.2奇偶监督码 (9) 3.调制与解调 (10) 3.1 MSK调制 (10) 3.1.1 MSK调制原理 (10) 3.1.2 MSK调制 (11) 3.2 MSK解调 (12) 4.信道描述 (13) 5.系统总体设计 (14) 附录MATLAB实现代码 (14) 1.通信系统概述 1.1一般通信系统模型 一般作为一个通信系统都由发送端和接收端两部分组成，而发送端则分为信息源和发送设备两部分，接收端与其对应的有接收端和受信者两部分，发送端和接收端之间则是我们信号传输所需要经过的信道，信号在信道中传输时会有噪声的混入，这也是我们的通信系统性能讨论的终点。 图1-1 一般通信系统 信息源是把各种原始消息转换成原始电信号的设备，它通过各种物理转换的方法从自然界中采集信息并把它们转换成相应的电信号，从而便于我们通过电子设备对其进行进一步的处理。受信者则是把接受到的电信号还原成自然界中信息的设备。 发送设备是通过对采集到的原始电信号进行一系列的处理把它变成适合于远距离传输的信号。在模拟传输系统中包括放大、滤波、模拟调制等过程；在数字传输系统中则包含编码、加密、数字调制等过程。接收设备则是上述过程的逆过程，将信道中传输的信号还原成易于处理的直接电信号。 信道是从发送设备到接收设备之间信号传输的物理煤质，分为无线信道和有限信道两大类，每种信道的特点不同，应用场合也不相同。 噪声源是笼统的一个说法，它集中表示分布于通信系统中的各处的噪声。 1.2数字通信系统模型 数字通信系统是通过数字信号来传递信息的通信系统。需要注意的是，这并不代表用于在信道中传输的信号就是数字信号，数字通信系统是通过数字信号来表示要传送的信息，而在传输过程中则还是利用高频调制的模拟信号传输。 图1-2 数字通信系统 题目基于SIMULINK的通信系统仿真 摘要 在模拟通信系统中，由模拟信源产生的携带信息的消息经过传感器转换成电信号，模拟基带信号在经过调制将低通频谱搬移到载波频率上适应信道，最终解调还原成电信号；在数字传输系统中，数字信号对高频载波进行调制，变为频带信号，通过信道传输，在接收端解调后恢复成数字信号。本文应用了幅度调制以及键控法产生调制与解调信号。 本论文中主要通过对SIMULINK工具箱的学习和使用，利用其丰富的模板以及本科对通信原理知识的掌握，完成了AM、DSB、SSB、2ASK、2FSK、2PSK三种模拟信号和三种数字信号的调制与解调，以及用SIMULINK进行设计和仿真。首先我进行了两种通信系统的建模以及不同信号系统的原理研究，然后将学习总结出的相应理论与SIMULINK中丰富的模块相结合实现仿真系统的建模,并且调整参数直到仿真波形输出，观察效果，最终对设计结论进行总结。 关键词通信系统调制 SIMULINK I 目录 1. 前言 (1) 1.1选题的意义和目的 (1) 1.2通信系统及其仿真技术 (2) 3. 现代通信系统的介绍 (3) 3.1通信系统的一般模型 (3) 3.2模拟通信系统模型和数字通信系统模型 (3) 3.2.1 模拟通信系统模型 (3) 3.2.2 数字通信系统模型 (4) 3.3模拟通信和数字通信的区别和优缺点 (5) 4. 通信系统的仿真原理及框图 (8) 4.1模拟通信系统的仿真原理 (8) 4.1.1 DSB信号的调制解调原理 ...................... 错误！未定义书签。 4.2数字通信系统的仿真原理 (9) 4.2.1 ASK信号的调制解调原理 (9) 5. 通信系统仿真结果及分析 (11) 5.1模拟通信系统结果分析 (11) 5.1.1 DSB模拟通信系统 (11) 5.2仿真结果框图 (11) 5.2.1 DSB模拟系统仿真结果 ........................ 错误！未定义书签。 5.3数字通信系统结果分析 (12) 5.3.1 ASK数字通信系统 (13) 5.4仿真结果框图 (13) 5.4.1 ASK数字系统仿真结果 (13) III 中国 一、原始社会（约170万年前到约公元前21世纪） 约0.5-0.7万年前河姆渡、半坡母系氏族公社 约0.4-0.5万年前大汶口文化中晚期，父系氏族公社 约4000多年前传说中的炎帝、黄帝、尧、舜、禹时期 二、奴隶社会（公元前2070年到公元前476年） 夏公元前2070年到公元前1600年 商公元前1600 年到公元前1046年 西周公元前1046年到公元前771年 春秋公元前770年到公元前476年 三、封建社会（公元前475年到公元1840年） 战国（公元前475年到公元前221年） 公元前356年商鞅开始变法 秦（公元前221年到公元前206年） 公元前221年秦统一，秦始皇确立郡县制，统一货币、度量衡和文字 公元前209年陈胜、吴广起义爆发 公元前207年巨鹿之战 公元前206年刘邦攻入咸阳，秦亡 公元前206年—公元前202年楚汉之争 西汉（公元前202年到公元8年） 公元前202年西汉建立 公元前138年张骞第一次出使西域 公元8年王莽夺取西汉政权，改国号新东汉（25年到220年） 25年东汉建立 105年蔡伦改进造纸术 132年张衡发明地动仪 184年张角领导黄巾起义 200年官渡之战 208年赤壁之战 三国（220年到280年） 220年魏国建立 221年蜀国建立 222年吴国建立 263年魏灭蜀 265年西晋建立，魏亡 西晋（265年到316年） 280年东晋灭吴 316年匈奴攻占长安，西晋结束东晋（317年到420年） 317年东晋建立 383年淝水之战 南北朝（420年到589年） 420年南朝宋建立 隋（581年到618） 581年隋朝建立 589年隋统一南北方 605年开始开通大运河 611年隋末农民起义开始 唐（618年到907年） 618年唐朝建立，隋朝灭亡627年-649年贞观之治 基于CAsyncSocket类的点对点通信客户机创建流程 ●通信流程： 1.服务器点击“监听”按钮开始监听，实现Create和Listen函数 2.客户机点击“连接”按钮进行连接，实现Connect函数 3.服务器端接受连接，并触发onAccept事件，实现函数Aeecpt 4.客户端或者服务器端点击“发送”按钮，发送文本框的数据 5.服务器端或者客户端接收数据，OnReveive事件被触发，实现函数Receive 6.客户端或者服务器端点击“断开”，执行函数close，触发另一端的onClose 事件 自定义类获取对话框指针的方法 1.先在CMyDialog.cpp中声明一个全局变量CMyDialog* pDlg; 2在OnInitDialog()初始化的时候，pDlg = this; 3.在自定义类使用的时候，在自定义的类的Cpp中添加extern CMyDialog* pDlg; 4.在自定类中使用pDlg->yourfunction(); ●编程过程： 客户端： 1、创建MFC应用程序，勾选windows socket选项，如创建工程名为client，自动创建类 CClientAPP和CClientDlg，并生成相应的源文件（.cpp）和头文件(.h)。APP代表应用程序。 Dlg代表对话框 2、布置界面如下图所示 3、建立类向导，给文本编辑框，列表框定义变量名及类型 4、插入基于CAsyncSocket的类，如取名clientsock，确定后类视图下右键单击类并载入虚函数onReceive(),onClose()，如果是服务器端还要加载onAccept 5、程序的各个类之间建立联系，具体步骤： 5.1对话框界面与套接字建立连接。在ClientDlg.h文件中将“clientsock.h”文件包含进来，使其能够访问套接字，代码为#include”clientsocket.h”;并添加成员变量m_clientsock，代码clientsock m_clientsock; 通信原理三级项目 班级：通信工程2班 姓名： 学号： 指导教师： 教务处 2016年 5月 远距离点对点数字通信系统设计 （燕山大学信息科学与工程学院） 摘要：本文讨论进行了远距离点对点数字通信系统的设计，着重讨论了模拟信号数字化的过程，其中包含了为了提高系统性能进行的信源编码技术和信道编码技术，我采用了HDB3码克服连0问题，利用奇偶监督码和差错重传机制控制误码率。另外，讨论了数字调制技术的实现，本文采用最小频移键控调制和解调技术，并讨论了在高斯白噪声信道条件下的此方法的可靠性和有效性。 关键词：脉冲编码调制，HDB3码，奇偶监督码，MSK调制，高斯白噪声，MATLAB 仿真 目录 1.通信系统概述 (3) 1.1一般通信系统模型 (3) 1.2数字通信系统模型 (4) 1.3远距离语音通信系统 (4) 2.信号数字化 (5) 2.1信号的抽样 (5) 2.1.1抽样定理 (5) 2.1.2脉冲幅度调制PAM (5) 2.2信源编码 (7) 2.2.1十三折线法 (7) 2.2.2脉冲编码调制PCM (9) 2.3信道编码 (10) 2.3.1 HDB3码 (10) 2.3.2奇偶监督码 (11) 3.调制与解调 (11) 3.1 MSK调制 (11) 3.1.1 MSK调制原理 (12) 3.1.2 MSK调制 (13) 3.2 MSK解调 (14) 4.信道描述 (15) 5.系统总体设计 (16) 附录 MATLAB实现代码 (17) 1.通信系统概述 1.1一般通信系统模型 一般作为一个通信系统都由发送端和接收端两部分组成，而发送端则分为信息源和发送设备两部分，接收端与其对应的有接收端和受信者两部分，发送端和接收端之间则是我们信号传输所需要经过的信道，信号在信道中传输时会有噪声的混入，这也是我们的通信系统性能讨论的终点。 图1-1 一般通信系统 信息源是把各种原始消息转换成原始电信号的设备，它通过各种物理转换的方法从自然界中采集信息并把它们转换成相应的电信号，从而便于我们通过电子设备对其进行进一步的处理。受信者则是把接受到的电信号还原成自然界中信息的设备。 发送设备是通过对采集到的原始电信号进行一系列的处理把它变成适合于远距离传输的信号。在模拟传输系统中包括放大、滤波、模拟调制等过程；在数字传输系统中则包含编码、加密、数字调制等过程。接收设备则是上述过程的逆过程，将信道中传输的信号还原成易于处理的直接电信号。 信道是从发送设备到接收设备之间信号传输的物理煤质，分为无线信道和有限信道两大类，每种信道的特点不同，应用场合也不相同。 噪声源是笼统的一个说法，它集中表示分布于通信系统中的各处的噪声。 中国的 一、原始社会（约170万年前到约公元前21世纪）约170万年前元谋人生活在云南元谋一带 约70-20万年前北京人生活在北京周口店一带 约1.8万年前山顶洞人开始氏族公社的生活 约0.5-0.7万年前河姆渡、半坡母系氏族公社 约0.4-0.5万年前大汶口文化中晚期，父系氏族公社 约4000多年前传说中的炎帝、黄帝、尧、舜、禹时期二、奴隶社会（公元前2070年到公元前476年） 夏公元前2070年到公元前1600年 公元前2070年禹传予启，夏朝建立 商公元前1600年到公元前1046年 公元前1600年商汤灭夏，商朝建立 公元前1300年商王盘庚迁都殷 西周公元前1046年到公元前771年 公元前1046年周武王灭商，西周开始 公元前841年国人暴动 公元前771年犬戎攻入镐京，西周结束 春秋公元前770年到公元前476年 公元前770年周平王迁都洛邑，东周开始 三、封建社会（公元前475年到公元1840年） 战国（公元前475年到公元前221年） 公元前356年商鞅开始变法 秦（公元前221年到公元前206年） 公元前221年秦统一，秦始皇确立郡县制，统一货币、度量衡和文字公元前209年陈胜、吴广起义爆发 公元前207年巨鹿之战 公元前206年刘邦攻入咸阳，秦亡 公元前206年—公元前202年楚汉之争 西汉（公元前202年到公元8年） 公元前202年西汉建立 公元前138年张骞第一次出使西域 公元8年王莽夺取西汉政权，改国号新 东汉（25年到220年） 25年东汉建立 73年班超出使西域 105年蔡伦改进造纸术 132年张衡发明地动仪 166年大秦王安敦派使臣到中国 184年张角领导黄巾起义 200年官渡之战 208年赤避之战 实验一 WinSock点对点通信程序 一、实验目的： WinSock是Windows操作系统下的Socket编程接口，通过WinSock函数库可以实现基于TCP/IP协议的进程之间通信。 ●理解基于WinSock的客户/服务器概念 ●掌握使用WinSock进行编程的方法 ●了解常见WinSock开发模式的使用 二、实验内容： 基于WinSock开发一个简单的客户/服务器文本传输程序，客户端能够发送由标准输入得到的文本，服务器能够接收并将其显示在标准输出上。 三、实验环境： 程序运行环境为以太网，采用TCP/IP协议栈，网络操作系统为Windows。程序开发环境为vs2012版本。 四、实验步骤： 步骤1 需求分析 程序功能为： （1）服务器可以接受任何客户的连接 （2）服务器在同一时刻只能与一个客户通信，直到该客户退出才可以接收下一个客户 （3）客户程序使用命令行参数指定服务器地址 （4）客户端输入的文本都发送给服务器 （5）客户使用Ctrl+C键停止发送，关闭连接 步骤2 服务器程序: 定义全局变量： SOCKET Server; // 服务器端套接字 SOCKADDR_IN Client_Addr; // 请求用户的Ip地址 SOCKET Sock_Conn; // 是否建立连接成功 char Buff_Recv[1024]; // 接收字符缓冲 char Buff_Send[1024]; // 发送字符缓冲区 服务器端主程序及用到的相关函数： void SLoad(); // 加载套接字库 void SCreate(); // 创建套接字 void SBind(); // 绑定套接字到一个IP地址和一个端口上 void SListen(); // 将套接字设置为监听模式等待连接请求 void SAccept(); /* 请求到来后，接受连接请求，返回一个新的对应于此次连接的套接字 */ void SClose(); // 关闭套接字 void SUnLoad(); // 卸载套接字库 void Receive(); // 接受请求 void Send(); // 服务器段发送字符串到客户端 主函数： int main(int argc, char* argv[]) { … /* 循环查询 */ while(1) { SLoad(); SCreate(); SBind(); SListen(); SAccept(); Receive(); SClose(); SUnLoad(); } 世界近代史 ●西方资本主义的发展 十四世纪意大利出现资本主义萌芽 十五世纪晚期英法中央集权国家形成，圈地运动开始 14-15世纪欧洲出现资本主义萌芽 1840年前后英国率先完成工业革命 18世纪60年代到19世纪中后期自由资本主义阶段 19世纪中后期垄断资本主义开始出现 1933年罗斯福新政后，国家垄断资本主义开始出现 二战结束到20世纪70年代初期西方资本主义国家普遍奉行国家干预的经济政策，出现了经济发展的“黄金时期” 20世纪70年代后美英等国逐渐发展出一种将政府干预与市场相结合的、国有制与私有制并存的“混合经济” ●西方人文主义的发展 十四至十六世纪欧洲文艺复兴运动在意大得兴起 十六世纪以后，文艺复兴从意大利传播到欧洲其他国家 十六世纪 1517年，马丁·路德拉开宗教改革序幕 十七至十八世纪 17世纪时，英国出现了早期启蒙运动 18世纪中叶，启蒙运动在法国进入高潮。 伏尔泰、孟德斯鸠、卢梭 ●新航路开辟： 1487－1488迪亚士远航到达非洲南部沿海 1492 哥伦布远航到达美洲 1497－1498 达伽马远航到达印度 1519－1522 麦哲伦船队环球航行 ●资产阶级代议制度的确立 1640 英国资产阶级革命开始 1688年英国光荣革命，资产阶级和新贵族的统治确立 1775－1783北美独立战争 1776北美大陆会议发表《独立宣言》，宣布美利坚合众国独立 1787年美国1787年宪法 1870－1871普法战争 1871年德意志统一最终完成德意志帝国宪法 1875年法兰西第三共和国宪法，在法律上正式确立共和政体 ●三次工业革命 18世纪60年代英国工业革命开始 1785瓦特的改良蒸汽机投入使用 19世纪70年代第二次工业革命开始 19世纪70年代，人类进入“电气时代” 19世纪七八十年代，内燃机问世 单片机多机通信系统 一、引言 随着单片机技术的不断发展，单片机的应用已经从单机向多机互联化方向发展。单片机在实时数据采集和数据处理方面，有着成本低、能满足一般要求、开发周期短等优点，其在智能家居、计算机的网络通信与数据传输、工业控制自动化等方面有着广泛的应用。 本系统是面向智能家居应用而设计的。在初期，采用红外无线通信方式，其传输距离短，适于一般家庭应用，且成本相对较低；待方案成熟、成本允许，可以改用GSM无线通信方式。 二、系统原理及方案设计 1 、系统框架介绍 本系统为基于51单片机的多机红外无线通信系统，由三个51单片机模块组成。其中一个作为主机（即上位机），负责接收来自从机1（即下位机）采集的数据信息，以及向从机2（即下位机）发送控制信息。从机1是数据采集模块，采集温度、光强等室内数据，并将其发送给主机。主机经分析处理，作出相应判断，并给从机2发送控制信息，使由从机2控制的电机作出相应反应，调节室内环境状况。 系统总体框图如下图1所示，图2为红外收发模块简图： 图1 系统总体框图 图2 红外收发模块简图 2 、多机通信原理介绍 在多机通信系统中，要保证主机与从机间可靠的通信，必须要让通信接口具有识别功能，51单片机串行口控制寄存器SCON中的控制位SM2正是为了满足这一要求而设置的。当串行口以方式2或方式3工作时，发送或接收的每一帧信息都是11位的，其中除了包含SBUF 寄存器传送的8位数据之外，还包含一个可编程的第9位数据TB8或RB8。主机可以通过对TB8赋予1或0，来区别发送的是数据帧还是地址帧。 根据串行口接收有效条件可知，若从机的SCON控制位SM2为1，则当接收的是地址帧时，接收数据将被装入SBUF并将RI标志置1， 一、原始社会（约170万年前到约公元前21世纪）二、奴隶社会（公元前2070年到公元前476年） 约170万年前元谋人生活在云南元谋一带夏公元前2070年到公元前1600年 约70-20万年前北京人生活在北京周口店一带公元前2070年禹传予启，夏朝建立 约1.8万年前山顶洞人开始氏族公社的生活商公元前1600 年到公元前1046年 约0.5-0.7万年前河姆渡、半坡母系氏族公社公元前1600年商汤灭夏，商朝建立 约0.4-0.5万年前大汶口文化中晚期，父系氏族公社公元前1300年商王盘庚迁都殷 约4000多年前传说中的炎帝、黄帝、尧、舜、禹时期西周公元前1046年到公元前771年 公元前1046年周武王灭商，西周开始 公元前841年国人暴动 公元前771年犬戎攻入镐京，西周结束 春秋公元前770年到公元前476年 公元前770年周平王迁都洛邑，东周开始 三、封建社会（公元前475年到公元1840年） 战国（公元前475年到公元前221年）公元前356年商鞅开始变法 秦（公元前221年到公元前206年） 公元前221年秦统一，秦始皇确立郡县制，统一货币、度量衡和文字 公元前209年陈胜、吴广起义爆发公元前207年巨鹿之战 公元前206年刘邦攻入咸阳，秦亡公元前206年—公元前202年楚汉之争 西汉（公元前202年到公元8年）公元前202年西汉建立 公元前138年张骞第一次出使西域公元8年王莽夺取西汉政权，改国号新 东汉（25年到220年）25年东汉建立 73年班超出使西域105年蔡伦改进造纸术 132年张衡发明地动仪166年大秦王安敦派使臣到中国 184年张角领导黄巾起义200年官渡之战 208年赤避之战三国（220年到280年）220年魏国建立 221年蜀国建立222年吴国建立 230年吴派卫温等率军队到台湾263年魏灭蜀 265年西晋建立，魏亡西晋（265年到316年） 280年东晋灭吴316年匈奴攻占长安，西晋结束 东晋（317年到420年）317年东晋建立 383年淝水之战南北朝（420年到589年） 420年南朝宋建立494年年到北魏孝文帝迁都洛阳 隋（581年到618）581年隋朝建立 589年隋统一南北方605年开始开通大运河 611年隋末农民起义开始，山东长白山农民起义爆发唐（618年到907年） 618年唐朝建立，隋朝灭亡627年-649年贞观之治 713年-741年开元盛世755年-763年安史之乱 875年-884年唐末农民战争五代（907年到960年） 907年后梁建立，唐亡，五代开始916年阿保机建立契丹国 北宋（960年到1127年）960年北宋建立 1005年宋、辽澶渊之盟1038年元昊建立西夏 11世纪中期毕升发明活字印刷术1069年王安石开始变法 1115年阿骨打建立金1125年金灭辽 中国重大历史事件时间表 一、原始社会（约170万年前到约公元前21世纪） 约170万年前元谋人生活在云南元谋一带 约70-20万年前北京人生活在北京周口店一带 约1.8万年前山顶洞人开始氏族公社 约0.5-0.7万年前河姆渡、半坡母系氏族公社的生活 约0.4-0.5万年前大汶口文化中晚期，父系氏族公社 约4000多年前传说中的炎帝、黄帝、尧、舜、禹时期 二、奴隶社会（公元前2070年到公元前476年） 夏公元前2070年到公元前1600年 公元前2070年禹传予启，夏朝建立 商公元前1600 年到公元前1046年 公元前1600年商汤灭夏，商朝建立 公元前1300年商王盘庚迁都殷 西周公元前1046年到公元前771年 公元前1046年周武王灭商，西周开始 公元前841年国人暴动 公元前771年犬戎攻入镐京，西周结束 春秋公元前770年到公元前476年 公元前770年周平王迁都洛邑，东周开始 三、封建社会（公元前475年到公元1840年） 战国（公元前475年到公元前221年） 公元前356年商鞅开始变法 秦（公元前221年到公元前206年） 公元前221年秦统一，秦始皇确立郡县制，统一货币、度量衡和文字公元前209年陈胜、吴广起义爆发 公元前207年巨鹿之战 公元前206年刘邦攻入咸阳，秦亡 公元前206年—公元前202年楚汉之争 西汉（公元前202年到公元8年） 公元前202年西汉建立 公元前138年张骞第一次出使西域 公元8年王莽夺取西汉政权，改国号新 东汉（25年到220年） 25年东汉建立 73年班超出使西域 105年蔡伦改进造纸术 132年张衡发明地动仪 166年大秦王安敦派使臣到中国 184年张角领导黄巾起义 200年官渡之战 208年赤避之战 三国（220年到280年） 220年魏国建立 221年蜀国建立 222年吴国建立 230年吴派卫温等率军队到台湾 263年魏灭蜀 265年西晋建立，魏亡 西晋（265年到316年） 280年东晋灭吴 316年匈奴攻占长安，西晋结束 东晋（317年到420年） 317年东晋建立 383年淝水之战 南北朝（420年到589年） 420年南朝宋建立 494年年到北魏孝文帝迁都洛阳 隋（581年到618） 581年隋朝建立 589年隋统一南北方 605年开始开通大运河 611年隋末农民起义开始，山东长白山农民起义爆发唐（618年到907年） 618年唐朝建立，隋朝灭亡 627年-649年贞观之治 713年-741年开元盛世 755年-763年安史之乱 875年-884年唐末农民战争 五代（907年到960年） 907年后梁建立，唐亡，五代开始 916年阿保机建立契丹国 北宋（960年到1127年） 960年北宋建立 1005年宋、辽澶渊之盟 1038年元昊建立西夏 11世纪中期毕升发明活字印刷术 1069年王安石开始变法 1115年阿骨打建立金 1125年金灭辽 南宋（1127年到1276年） 摘要 在当前飞速发展的信息时代，随着数字通信技术计算机技术的发展，以及通信网络与计算机网络的相互融合，信息技术已成为21世纪社会国际化的强大动力。Matlab软件包含众多的功能各异的工具箱，涉及领域包括：数字信号处理、通信技术、控制系统、神经网络、模糊逻辑、数值统计、系统仿真和虚拟现实技术等。作为一个功能强大的数学工具软件，在很多领域中得到本文利用Matlab对点对点通信进行仿真实验，实现信号从信源到信宿过程的模拟并获得信噪比与误码率的曲线图，研究了相移键控调制下信噪比与误码率的关系并比较了不同进制相移键控调制下误码率—信噪曲线的异同，同时也研究了不同中继信道对误码率—信噪比曲线的影响了广泛的应用。 关键字：MATLAB仿真；点对点通信；PSK；中继信道；误码率 基于MATLAB的点对点通信仿真....................................................................... 错误！未定义书签。摘要 (1) 1 引言 (2) 1.1 课程设计的目的和意义 (2) 1.2 课程设计内容 (2) 2仿真环境简介 (3) 3系统理论分析 (3) 3.1通信系统模型 (3) 3.2 相移键控原理 (4) 3.2.1二进制相移键控原理 (4) 3.2.2 多进制相移键控调制原理 (5) 4 仿真过程基于Matlab的实现 (6) 4.1仿真条件及符号说明 (6) 4.1.1仿真条件： (6) 4.1.2符号说明 (6) 5仿真结果 (8) 6仿真模型分析 (9) 6.1模型结果分析 (9) 6.2模型优缺点分析及改进方案 (10) 6.2.1优缺点分析 (10) 用java实现的点对点通信程序的设计 通信0903班学号：姓名：指导老师：王国才、杨政宇 一设计目标： 1.使用Java高级面向对象编程语言编写一个网络聊天程序。 2.理解Socket的基本概念工作原理，掌握Socket的建立、监听、连接、发送数据和接收数据 3.环境要求：Windows95/98/2000/XP,WinSocke 4.能将键盘上输入的数据发送到另一台计算机上； 5.能将接收到的数据显示到屏幕窗口内； 6.类似于一般的主流网络即时聊天程序为了简化程序和系统结构，将“客户端——服务器——客户端”的数据传输方式改为“客户端——服务器”的模式。 7.程序应该具有图形界面，要具备聊天程序的基本雏形。 二设计原理与方法 1. TCP/IP协议的介绍 TCP/IP（传输控制协议/网际协议）是互联网中的基本通信语言或协议。在私网中，它也被用作通信协议。当你直接网络连接时，你的计算机应提供一个TCP/IP程序的副本，此时接收你所发送的信息的计算机也应有一个TCP/IP程序的副本。 TCP/IP是一个两层的程序。高层为传输控制协议，它负责聚集信息或把文件拆分成更小的包。这些包通过网络传送到接收端的TCP层，接收端的TCP层把包还原为原始文件。低层是网际协议，它处理每个包的地址部分，使这些包正确的到达目的地。网络上的网关计算机根据信息的地址来进行路由选择。即使来自同一文件的分包路由也有可能不同，但最后会在目的地汇合。 TCP/IP使用客户端/服务器模式进行通信。TCP/IP通信是点对点的，意思是通信是网络中的一台主机与另一台主机之间的。TCP/IP与上层应用程序之间可以说是“没有国籍的”，因为每个客户请求都被看做是与上一个请求无关的。正是它们之间的“无国籍的”释放了网络路径，才是每个人都可以连续不断的使用网络。许多用户熟悉使用TCP/IP协议的高层应用协议。包括万维网的超文本传输协议（HTTP），文件传输协议（FTP），远程网络访问协议(Telnet)和简单邮件传输协议（SMTP）。这些协议通常和TCP/IP协议打包在一起。使用模拟电话调制解调器连接网络的个人电脑通常是使用串行线路接口协议（SLIP）和点对点协议（P2P）。这些协议压缩IP包后通过拨号电话线发送到对方的调制解调器中。与TCP/IP协议相关的协议还包括用户数据报协议（UDP），它代替TCP/IP协议来达到特殊的目的。其他协议是网络主机用来交换路由信息的，包括Internet 控制信息协议（ICMP），内部网关协议（IGP），外部网关协议（EGP），边界网关协议（BGP）。 世界的重大历史事件时间表 大约三百万年前地球上出现人类 公元前3100年左右埃及形成统一的奴隶制国家 公元前3000年左右两河流域出现奴隶制城市国家 公元前3000年代中期印度河流域哈拉帕文化 公元前2100年左右埃及奴隶河贫民大起义 公元前1894年古巴比伦王国建立 公元前1000年左右努比亚建立奴隶制国家 公元前594年雅典的梭伦改革 公元前六世纪居鲁士统一波斯，佛教在印度产生 公元前539年波斯占领巴比伦 公元前525年波斯灭埃及 公元前509年罗马成立贵族专政的奴隶制共和国 公元前330年波斯被马其顿灭亡 公元前三世纪摩揭陀国统一印度大部分地区 公元前73-71年斯巴达克起义 公元前27年屋大维建立罗马的元首制，共和国转为帝国 公元前后朝鲜半岛出现高句丽奴隶制国家 公元初东非阿克苏姆奴隶制国家兴起 公元一世纪基督教产生 公元三世纪日本大和奴隶制国家兴起 313年基督教在罗马取得合法地位 四世纪北非发生“阿哥尼斯特”运动 378年西哥特人在阿德里亚堡击败罗马军队 395年罗马分裂为东西两部 410年西哥特人一度占领罗马 476年西罗马帝国灭亡，西欧奴隶制度崩溃 六世纪初法兰克王国建立 622年穆罕默德从麦加出走麦地拉，伊斯兰教纪元 八世纪中叶阿拉伯帝国形成 646年日本大化改新 676年新罗统一朝鲜 九世纪早期英吉利王国形成 843年查里曼帝国分裂，法兰西、德意志、意大利雏形产生九世纪封建制度在西欧确立 962年神圣罗马帝国建立 1054年基督教会分裂 1066年法国诺曼底公爵征服英国 十一世纪中叶加纳王国全盛时期 1192年日本幕府政治建立 十三世纪埃塞俄比亚封建国家兴起 十四世纪马里王国全盛时期，意大利出现资本主义萌芽实验二 socket下点对点通信的实现
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