In this manuscript,we report evidence to support the dependence of Dn4000(4000A break strength to trace stellar ages) on central active galactic nuclei(AGN) activity traced by narrow emission line properties in local ...In this manuscript,we report evidence to support the dependence of Dn4000(4000A break strength to trace stellar ages) on central active galactic nuclei(AGN) activity traced by narrow emission line properties in local Type-2AGN in SDSS DR 16.Based on the measured Dn4000 and flux ratios of [O Ⅲ] to narrow Hβ(O3HB) and [N Ⅱ] to narrow Hα(N2HA) and narrow Hα line luminosity L_(Hα),linear dependence of the Dn4000 on the O3HB,N2HA and L_(Hα)in the local Type-2 AGN can provide clues to support the dependence of Dn4000 on properties with narrow emission lines.Linear correlations between the Dn4000 and the O3HB and N2HA can be found in the local Type-2 AGN,with Spearman rank correlations of about-0.39 and 0.53.Meanwhile,stronger dependence of the Dn4000 on the L_(Hα)can be confirmed in Type-2 AGN,with a Spearman rank correlation coefficient of about-0.7.Moreover,combining the L_(Hα)and the N2HA,a more robust and stronger linear correlation can be confirmed between the Dn4000 and the new parameter LR=0.2 log(L_(Hα))-0.5 log(N2HA),with a Spearman rank correlation coefficient of about-0.76 and with smaller rms scatters.After considering necessary effects,the dependence of Dn4000 on LR is stable and robust enough for the local Type-2 AGN,indicating that the LR on the narrow emission lines can be treated as a better indicator to statistically trace stellar ages of samples of more luminous AGN with weaker host galaxy absorption features.展开更多
We estimated radiative efficiency,spin and supermassive black hole(SMBH)mass values for sample of 33 distant low luminosity active galactic nuclei(AGNs).The distribution of the estimated spin values(majority of object...We estimated radiative efficiency,spin and supermassive black hole(SMBH)mass values for sample of 33 distant low luminosity active galactic nuclei(AGNs).The distribution of the estimated spin values(majority of objects have a spin greater than 0.8)is fairly typical for many types of AGNs.The dependence of the estimated spin values on the estimated SMBH masses shows strong correlation between them,which suggests a rapid increase in spin with mass,i.e.,that the main mechanism of mass growth in this case is disk accretion.We did not find any significant qualitative differences in the spin characteristics between our objects and objects of other types considered in the paper.展开更多
Utilizing a range of techniques including multi-band light curves,softness ratio analysis,structure functions,rms spectra,cross-correlation functions,and ratios of spectra from different intervals,we present a compreh...Utilizing a range of techniques including multi-band light curves,softness ratio analysis,structure functions,rms spectra,cross-correlation functions,and ratios of spectra from different intervals,we present a comprehensive study of the complex X-ray spectral variability in Seyfert 1 galaxy Ark 120,through re-analyzing its six XMMNewton observations taken between 2003 and 2014.We find a clear“softer-when-brighter”trend in the 2-10 keV power-law component over long timescales,with this trend being timescale dependent,as it is much weaker on shorter timescales,similar to that previously detected in NGC 4051.Notably,a rare“harder-when-brighter”trend is observed during one exposure,indicating dynamic changes in the spectral variability behavior of the power-law component.This exceptional exposure,with the spectral variability indeed marked by a power-law pivoting at an unusually low energy of~2 keV,suggests intricate variations in the thermal Comptonization processes within the corona.Furthermore,when the data below 2 keV are included,we identify that the soft excess component adds significant complexity to the spectral variability,such as evidenced by a transition from“harder-when-brighter”to“softer-when-brighter”during another single exposure.Such extra complexity arises because the variability of the soft excess sometimes follows and sometimes does not follow the changes in the power-law component.Our findings underscore the necessity of applying multiple analytic techniques to fully capture the multifaceted spectral variability of AGNs.展开更多
Changing-look(CL)active galactic nuclei(AGNs)are an extremely rare type of AGNs,characterized by the appearance(turn-on)or disappearance(turn-off)of broad emission lines within months to years.We construct a sample of...Changing-look(CL)active galactic nuclei(AGNs)are an extremely rare type of AGNs,characterized by the appearance(turn-on)or disappearance(turn-off)of broad emission lines within months to years.We construct a sample of 211 CL AGN candidates by systematically searching the Sloan Digital Sky Survey spectra classified as GALAXY,but with the Zwicky Transient Facility and Near-Earth Object Wide-Field Infrared Explorer midinfrared light curves showing significant variability,at the redshift range from 0.1 to 0.75.To examine the success rate of this method,we cross-match the candidate sample with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope and the Dark Energy Spectroscopic Instrument for repeat spectra,finding that the success rate of this method is 50%.By incorporating previously reported CL AGNs,a total of 48 CL AGNs have been identified within our sample,including two recurrent CL AGNs newly confirmed in this work.Our results suggest that the typical rest-frame timescale of CL behavior is from 1.7 to 18.1 yr,which is inconsistent with the obscuration model,and the Eddington ratios of CL AGNs are about 0.01 in the bright state.Additionally,our CL AGN sample follows the M_(BH)–σ_(*)relation of quiescent galaxies.In the future,we expect to detect more galaxies turning into Type 1 AGNs in this CL AGN candidate sample.展开更多
The feeding and feedback processes at the vicinity of a supermassive black hole(BH)are essential for our understanding of the connection between supermassive BH and its host galaxy.In this work,we provide a detailed i...The feeding and feedback processes at the vicinity of a supermassive black hole(BH)are essential for our understanding of the connection between supermassive BH and its host galaxy.In this work,we provide a detailed investigation,both observational and theoretical,on the diffuse(~2"-20",~0.08-0.8 pc)X-ray emission around Sgr A*.Over two-decade Chandra observations are gathered to obtain highest signal-to-noise to date.We find that,the line center of iron lines of the outer 8"-18"region,ε_(c)=6.65+0.02-0.03 keV,is comparable to that(ε_(c)=6.60+0.05-0.03 keV)of the inner 2"-5"region.This is somewhat unexpected,since the gas temperature decreases further away from the central BH.Based on a dynamical inflow-outflow model that considers the gas feeding by stellar winds from Wolf-Rayet stars,we calculate the X-ray spectrum based on both the conventional collisional ionization equilibrium(CIE)assumption,and the newly developed non-equilibrium ionization(NEI)assumption.We find that,theoretically gases within~8"-10"remain in a CIE state,outside of this radius they will be in the NEI state.A comparison of the properties of~6.6 keV iron lines between CIE and NEI is addressed.Interestingly,the NEI interpretation of outer region is supported by the Chandra line center ε_(c) measurements of this region.展开更多
Active galactic nuclei(AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley...Active galactic nuclei(AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type Ⅰ/Ⅱ(FRI/Ⅱ) radio galaxies. Following our previous work(Fan et al.), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRⅡ galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work.展开更多
High resolution deep imaging from space and adaptive optics techniques with large ground-based facilities have enabled studies examining faint host galaxies of high redshift quasi-stellar objects (QSOs). However, the ...High resolution deep imaging from space and adaptive optics techniques with large ground-based facilities have enabled studies examining faint host galaxies of high redshift quasi-stellar objects (QSOs). However, the related image processing techniques, especially for a precise point-spread function (PSF) reconstruction and characterization of the host galaxy light profiles, have yet to be optimized. We present here the scientific performance of a principal component analysis (PCA) based PSF subtraction of the central bright point source of high redshift QSO images, as well as further characterization of the host galaxy profile by directly fitting a Sèrsic model to the residual image using the Markov Chain Monte Carlo (MCMC) algorithm. With a set of reference PSF star images which represent interleaving exposures between the QSO imaging, we can create an orthogonal basis of eigen-images and restore the PSF of QSO images by projecting the QSO images onto the basis. In this way, we can quantify the modes in which the PSF varies with time by a basis function that characterizes the temporal variations of the reference star as well as the QSO images. To verify the algorithm, we performed a simulation and applied this method to one of the high-z QSO targets from Mechtley et al. We demonstrate that the PCA-based PSF subtraction and further modeling of the galaxy’s light profile using MCMC fitting would sufficiently remove the effects from central dominating point sources, and improve characterization ability for the host galaxies of high-z QSOs to the background noise level which is much better than previous two-component fitting procedures.展开更多
We present an independent catalog(FRIIRGcat)of 45,241 Fanaroff–Riley TypeⅡ(FR-Ⅱ)radio galaxies compiled from the Very Large Array Faint Images of the Radio Sky at Twenty-centimeters(FIRST)survey and employed the de...We present an independent catalog(FRIIRGcat)of 45,241 Fanaroff–Riley TypeⅡ(FR-Ⅱ)radio galaxies compiled from the Very Large Array Faint Images of the Radio Sky at Twenty-centimeters(FIRST)survey and employed the deep learning method.Among them,optical and/or infrared counterparts are identified for 41,425 FR-Ⅱs.This catalog spans luminosities 2.63×10^(22)≤L_(rad)≤6.76×10^(29)W Hz^(-1)and redshifts up to z=5.01.The spectroscopic classification indicates that there are 1431 low-excitation radio galaxies and 260 high-excitation radio galaxies.Among the spectroscopically identified sources,black hole masses are estimated for 4837 FR-Is,which are in 10^(7.5)■M_(BH)■10^(9.5)M_(⊙).Interestingly,this catalog reveals a couple of giant radio galaxies(GRGs),which are already in the existing GRG catalog,confirming the efficiency of this FR-I catalog.Furthermore,284new GRGs are unveiled in this new FR-I sample;they have the largest projected sizes ranging from 701 to1209 kpc and are located at redshifts 0.31<z<2.42.Finally,we explore the distribution of the jet position angle and it shows that the faint Images of the FIRST images are significantly affected by the systematic effect(the observing beams).The method presented in this work is expected to be applicable to the radio sky surveys that are currently being conducted because they have finely refined telescope arrays.On the other hand,we are expecting that further new methods will be dedicated to solving this problem.展开更多
The theoretical model suggests that relativistic jets of active galactic nuclei(AGNs)rely on the black hole spin and/or accretion.We study the relationship between jet,accretion,and spin using supermassive black hole ...The theoretical model suggests that relativistic jets of active galactic nuclei(AGNs)rely on the black hole spin and/or accretion.We study the relationship between jet,accretion,and spin using supermassive black hole samples with reliable spin of black holes.Our results are as follows:(1)There is a weak correlation between radio luminosity and the spin of the black hole for our sample,which may imply that the jet of the supermassive black hole in our sample depends on the other physical parameters besides black hole spins,such as accretion disk luminosity.(2)The jet power of a supermassive black hole can be explained by the hybrid model with magnetic field of corona.(3)There is a significant correlation between radio-loudness and black hole spin for our sample.These sources with high radio-loudness tend to have high black hole spins.These results provide observational evidence that the black hole spin may explain the bimodal phenomena of radio-loud and radio-quiet AGNs.展开更多
In this paper, we use a method to dctermine some basic parameters for the γ-ray loud blazars. The parameters include the central black mass （M）, the boosting factor （δ）, the propagation angle （Ф）, the distanc...In this paper, we use a method to dctermine some basic parameters for the γ-ray loud blazars. The parameters include the central black mass （M）, the boosting factor （δ）, the propagation angle （Ф）, the distance along the axis to the site of the γ-ray production （d）. A sample including 32 γ-ray loud blazars with available variability time scales has been used to discuss the above properties. In this method, the γ-ray energy, the emission size and the property of the accretion disc determine the absorption effect. If we take the intrinsic γ-ray luminosity to be λ times the Eddington luminosity, i.e. Lγ^in =λLEdd, then we have the following results： the mass of the black hole is in the range of （0.59 - 67.99） ×10^7M⊙ （λ = 1.0） or （0.90 - 104.13） × 10^7M⊙ （λ = 0.1）; the boosting factor （5） in the range of 0.16 - 2.09（λ = 1.0） or 0.24 - 2.86 （λ = 0.1）; the angle （Ф） in the range of 9.53°- 73.85° （λ =1.0） or 7.36° - 68.89° （λ = 0.1）; and the distance （d/Rg） in the range of 22.39 - 609.36 （λ = 1.0） or 17.54 - 541.88 （λ = 0.1）.展开更多
We use the recently discovered simple photometric parameter Central Intensity Ratio(CIR)determined for a sample of 57 nearby(z<0.02)Seyfert galaxies to explore the central features of galaxies and their possible co...We use the recently discovered simple photometric parameter Central Intensity Ratio(CIR)determined for a sample of 57 nearby(z<0.02)Seyfert galaxies to explore the central features of galaxies and their possible connection with galaxy evolution.The sample of galaxies shows strong anti-correlation between CIR and mass of their central supermassive black holes(SMBHs).The SMBH masses of ellipticals are systematically higher for a given CIR value than those for lenticulars and spirals in the sample.However,the correlation between CIR and central velocity dispersion is weak.CIR appears less influenced by the excess flux produced by the central engine in these galaxies,when compared to spectroscopic parameters like velocity dispersion and OⅣflux,and proves to be a fast and reliable tool for estimating central SMBH mass.展开更多
Theγ-ray emitting compact symmetric objects(CSOs)PKS 1718-649,NGC 3894,and TXS 0128+554 are lobedominated in the radio emission.In order to investigate theirγ-ray radiation properties,we analyze the~14yr Fermi/LAT o...Theγ-ray emitting compact symmetric objects(CSOs)PKS 1718-649,NGC 3894,and TXS 0128+554 are lobedominated in the radio emission.In order to investigate theirγ-ray radiation properties,we analyze the~14yr Fermi/LAT observation data of the three CSOs.They all show the low luminosity(1041-1043 erg s-1)and no significant variability in theγ-ray band.Theirγ-ray average spectra can be well fitted by a power-law function.These properties ofγ-rays are clearly different from theγ-ray emitting CSOs CTD 135 and PKS 1413+135,for which theγ-rays are produced by a restarted aligned jet.In the L_(γ)-Γ_(γ)plane,the three CSOs are also located at the region occupied by radio galaxies(RGs)while CTD 135 and PKS 1413+135 display a similar feature to blazars.Together with a similar radio emission property toγ-ray emitting RGs Cen A and Fornax A,we speculate that theγ-rays of the three CSOs stem from their extended mini-lobes.The broadband spectral energy distributions of the three CSOs can be well explained by the two-zone leptonic model,where theirγ-rays are produced by the inverse Compton process of the relativistic electrons in extended regions.By extrapolating the observed Fermi/LAT spectra to the very high energy band,we find that TXS 0128+554 among the three CSOs may be detected by the Cherenkov Telescope Array in the future.展开更多
Giant gaseous layers(termed“superdisks”)have been hypothesized in the past to account for the strip-like radio emission gap(or straight-edged central brightness depression)observed between twin radio lobes,in over a...Giant gaseous layers(termed“superdisks”)have been hypothesized in the past to account for the strip-like radio emission gap(or straight-edged central brightness depression)observed between twin radio lobes,in over a dozen relatively nearby powerful Fanaroff-Riley Class II radio galaxies.They could also provide a plausible alternative explanation for a range of observations.Although a number of explanations have been proposed for the origin of the superdisks,little is known about their material content.Some X-ray observations of superdisk candidates indicate the presence of hot gas,but a cool dusty medium also seems to be common.If they are entirely or partly composed of neutral gas,then it may be directly detectable and we report here a first attempt to detect/image any neutral hydrogen gas present in the superdisks that are inferred to be present in four nearby radio galaxies.We have not found a positive H I signal in any of the four sources,resulting in tight upper limits on the H I number density in the postulated superdisks,estimated directly from the central rms noise values of the final radio continuum subtracted image.The estimated ranges of the upper limit on neutral hydrogen number density and column density are 10^-4-10^-3 atoms per cm3 and 10^19-10^20 atoms per cm^2,respectively.No positive H I signal is detected even after combining all the four available H I images(with inverse variance weighting).This clearly rules out an H I dominated superdisk as a viable model to explain these structures,however,the possibility of a superdisk being composed of warm/hot gas still remains open.展开更多
In previous paper we have shown that the soft X-ray spectra of two types of Seyfert 1 galaxies behave statistically differently with increasing intensity. In order to see how the spectrum of blazars changes, we made...In previous paper we have shown that the soft X-ray spectra of two types of Seyfert 1 galaxies behave statistically differently with increasing intensity. In order to see how the spectrum of blazars changes, we made plots of Hardness Ratio 1 versus Count Rates (HR1-Cts) for 18 blazars observed by ROSAT/PSPC. According to our criteria, ten showed a positive HR1-Cts correlation, two a negative correlation, and the remaining six, no clear correlation. Thus, most blazars of our sample show a hardening spectrum during overall flux increase, though some vary randomly. By investigating the photon index of these objects and different radiation theories, we argue that relative dominance between the synchrotron and inverse Compton emission in the soft X-ray band can well account for the differing spectral behaviours and that the different spectral variations might represent a sequence of synchrotron peaked frequency.展开更多
It has long remained an open question as to the geometry of the broad line region(BLR)in active galactic nuclei(AGNs).The reverberation mapping technique which measures the response of the broad emission lines to the ...It has long remained an open question as to the geometry of the broad line region(BLR)in active galactic nuclei(AGNs).The reverberation mapping technique which measures the response of the broad emission lines to the ionizing continuum,when combined with multiwavelength continuum fitted by sophisticated accretion disks,provides a way of probing the BLR geometry.We analyze a sample of 35 AGNs,which have been monitored by the reverberation mapping campaign.In view of energy budget,the reverberation-based BH masses are found to be in agreement with those obtained by accretion disk models in two thirds of the present sample while the reverberation mapping methods underestimate the BH masses in about one third of objects,as also suggested by CoUin et al.in a recent work.We point out that there are obviously two kinds of BLR geometry,which are strongly dependent on the Eddington ratio,and separated by the value LBol/LEdd-0.1.These results prefer a scenario of the disk and wind configuration of the BLR and identify the Eddington ratio as the physical driver regulating the wind in the BLR.展开更多
We present our initial results from a study of 14 （U）LIRGs with a doublenucleus （z 〈0.15） and an AGN signature in the Chandra archive.The goals of our study are to search for more possible cases of binary AGNs an...We present our initial results from a study of 14 （U）LIRGs with a doublenucleus （z 〈0.15） and an AGN signature in the Chandra archive.The goals of our study are to search for more possible cases of binary AGNs and to investigate the X-ray properties and energy sources of these energetic objects,a major effort devoted specifically to searching for binary AGNs from （U）LIRGs.Our studies suggest that Mrk 266 might be a new candidate in hosting binary AGNs supported by X-ray observations.Our analysis shows that most （U）LIRGs are essentially weak X-ray sources and are not dominated by AGNs,due to both the lack of Fe K line detections and weak emission in the hard X-ray band.We find evidence for thermal emission with temperature kT ～ 0.7keV in seven nuclear regions,and this component is possibly associated with the nuclear or circumnuclear starburst.The soft and hard X-ray to far-infrared ratios also suggest that most （U）LIRGs are not energetically dominated by AGNs.Therefore,this study only provides one additional candidate of binary AGNs.We cannot rule out the existence of low luminosity AGNs and thus binary AGNs in all of them,particularly,those highly obscured and spatially unresolved systems.Nine of 14 （U）LIRGs,including three previously known binary AGNs and a new candidate Mrk 266,clearly have obvious X-ray counterparts to their double optical/near-IR nuclei.whereas only two out of 14 have one obvious X-ray counterpart detected.Additionally,Arp 220 and Mrk 273 are not spatially resolved owing to their small nuclear separations （～ 1″）,and no展开更多
There is observational evidence that broad-line regions （BLRs） exist in most active galactic nuclei （AGNs）, but their origin is still unclear. One scenario is that the BLRs originate from winds accelerated from th...There is observational evidence that broad-line regions （BLRs） exist in most active galactic nuclei （AGNs）, but their origin is still unclear. One scenario is that the BLRs originate from winds accelerated from the hot coronae of the disks, and the winds are suppressed when the black hole is accreting at low rates. This model predicts a relation between rh （m ~ /~f//~fEdd） and the FWHM of broad emission lines. We estimate the central black hole masses for a sample of bright AGNs by using their broad Hβ line-widths and optical luminosities. The dimensionless accretion rates rh = M/MEdd are derived from the optical continuum luminosities by using two different models： using an empirical relation between the bolometric luminosity Lbol and the optical luminosity （rh = Lbol/LEdd, a fixed radiative efficiency is adopted）; and calculating the optical spectra of accretion disks as a function of rh. We find a slgmficant correlation between the denved of and the observed line width of Hβ, FWHMα m^-0.aT, which almost overlaps the disk-corona model calculations, if the viscosity a α≈ 0.1 - 0.2 is adopted. Our results provide strong evidence for the physical link between the BLRs and accretion disks in AGNs.展开更多
Inertial mass is detected on Earth only when matter is accelerated or decelerated. Recently evidence has been reported for a low-level velocity oscillation with a period of 39 ± 1 Mpc (127 ± 3 Myr) superimpo...Inertial mass is detected on Earth only when matter is accelerated or decelerated. Recently evidence has been reported for a low-level velocity oscillation with a period of 39 ± 1 Mpc (127 ± 3 Myr) superimposed on the Hubble flow. Like the Hubble flow, this oscillation is assumed to be an expansion and contraction of space itself. If space is oscillating as it expands and the Hubble flow contains a superimposed velocity ripple, matter on Earth will experience alternating accelerations and decelerations relative to the rest of the matter in the Universe. The acceleration curve can be obtained from the velocity oscillation curve simply by taking the magnitude of the derivative of the velocity curve and the acceleration curve is found here to have a period of 63.5 ± 1.5 Myr. Evidence has also been claimed recently for a ubiquitous ~62 ± 3 Myr periodic fluctuation superimposed on general trends in the fossil biodiversity on Earth. The periods of the acceleration curve oscillation and fossil biodiversity fluctuations are thus identical within the errors. A second, weaker fluctuation is also detected in both the Hubble flow and fossil biodiversity trends. They too have identical periods of ~140 Myr. From this excellent agreement, it is argued here that it is the oscillation in the Hubble flow, through an inertia-like phenomenon involving all the matter in the universe that has produced the fluctuations in the fossil biodiversity on Earth. This may represent the first instance where observational evidence supporting Mach’s Principle of Inertia has been found.展开更多
According to the standard model, an active galactic nucleus (AGN) consists of an inner accretion disk with a jet around a central massive black hole, and a number of outer broad line regions (BLRs) and narrow line reg...According to the standard model, an active galactic nucleus (AGN) consists of an inner accretion disk with a jet around a central massive black hole, and a number of outer broad line regions (BLRs) and narrow line regions (NLRs). The geometrical relationship between the BLRs and the accretion disk is not well understood. Assuming the motion of the BLRs is virialized and its configuration is disk-like, we derived its inclination to the line of sight for a sample of AGNs from their bulge stellar velocity dispersion, their size of the BLRs and their Hβ linewidth. Compared with the inclination of the accretion disk obtained from the X-ray Fe Kα emission lines, we found that there is no positive correlation between the two. Our results showed that BLRs are not coplanar with the accretion disk and that we should be cautious of using the BLRs inclination as the disk inclination. The non-coplanar geometry of the outer BLRs and the inner accretion disk provides clues to the origin of BLRs and the properties of the accretion disk. Our preferable interpretation is that BLRs arise out of the outer part of a warped accretion disk.展开更多
The relativistic beaming model has been successfully used to explain many of the observational properties of active galactic nuclei. In this model the total emission is formed by two components, one beamed, one unbeam...The relativistic beaming model has been successfully used to explain many of the observational properties of active galactic nuclei. In this model the total emission is formed by two components, one beamed, one unbeamed. However, the exact contribution from each component in unresolved sources is still not clear. In the radio band, the core and extended emissions are clearly separated. We adopt the method proposed by Kembhavi to separate the two contributions in the X-ray emissions in a sample of 19 gamma-ray loud blazars. It is clearly shown that the beamed emission dominates the X-ray flux and the unbeamed X-ray emission is correlated with the extended radio emission of the considered objects. We also find that the ratio of the beamed to the unbeamed X-ray luminosity is correlated with the X-ray spectral index, an effect that should be a consequence of the underlying X-ray emission mechanism.展开更多
基金Guang Xi University for kind financial supportNSFC-12173020 and NSFC-12373014 and the the Guangxi Talent Programme (Highland of Innovation Talents) for kind grant support。
文摘In this manuscript,we report evidence to support the dependence of Dn4000(4000A break strength to trace stellar ages) on central active galactic nuclei(AGN) activity traced by narrow emission line properties in local Type-2AGN in SDSS DR 16.Based on the measured Dn4000 and flux ratios of [O Ⅲ] to narrow Hβ(O3HB) and [N Ⅱ] to narrow Hα(N2HA) and narrow Hα line luminosity L_(Hα),linear dependence of the Dn4000 on the O3HB,N2HA and L_(Hα)in the local Type-2 AGN can provide clues to support the dependence of Dn4000 on properties with narrow emission lines.Linear correlations between the Dn4000 and the O3HB and N2HA can be found in the local Type-2 AGN,with Spearman rank correlations of about-0.39 and 0.53.Meanwhile,stronger dependence of the Dn4000 on the L_(Hα)can be confirmed in Type-2 AGN,with a Spearman rank correlation coefficient of about-0.7.Moreover,combining the L_(Hα)and the N2HA,a more robust and stronger linear correlation can be confirmed between the Dn4000 and the new parameter LR=0.2 log(L_(Hα))-0.5 log(N2HA),with a Spearman rank correlation coefficient of about-0.76 and with smaller rms scatters.After considering necessary effects,the dependence of Dn4000 on LR is stable and robust enough for the local Type-2 AGN,indicating that the LR on the narrow emission lines can be treated as a better indicator to statistically trace stellar ages of samples of more luminous AGN with weaker host galaxy absorption features.
文摘We estimated radiative efficiency,spin and supermassive black hole(SMBH)mass values for sample of 33 distant low luminosity active galactic nuclei(AGNs).The distribution of the estimated spin values(majority of objects have a spin greater than 0.8)is fairly typical for many types of AGNs.The dependence of the estimated spin values on the estimated SMBH masses shows strong correlation between them,which suggests a rapid increase in spin with mass,i.e.,that the main mechanism of mass growth in this case is disk accretion.We did not find any significant qualitative differences in the spin characteristics between our objects and objects of other types considered in the paper.
基金supported by the National Natural Science Foundation of China (NSFC,grant Nos.12033006,12192221,and 123B2042)the Cyrus Chun Ying Tang Foundationsfunded by ESA Member States and NASA
文摘Utilizing a range of techniques including multi-band light curves,softness ratio analysis,structure functions,rms spectra,cross-correlation functions,and ratios of spectra from different intervals,we present a comprehensive study of the complex X-ray spectral variability in Seyfert 1 galaxy Ark 120,through re-analyzing its six XMMNewton observations taken between 2003 and 2014.We find a clear“softer-when-brighter”trend in the 2-10 keV power-law component over long timescales,with this trend being timescale dependent,as it is much weaker on shorter timescales,similar to that previously detected in NGC 4051.Notably,a rare“harder-when-brighter”trend is observed during one exposure,indicating dynamic changes in the spectral variability behavior of the power-law component.This exceptional exposure,with the spectral variability indeed marked by a power-law pivoting at an unusually low energy of~2 keV,suggests intricate variations in the thermal Comptonization processes within the corona.Furthermore,when the data below 2 keV are included,we identify that the soft excess component adds significant complexity to the spectral variability,such as evidenced by a transition from“harder-when-brighter”to“softer-when-brighter”during another single exposure.Such extra complexity arises because the variability of the soft excess sometimes follows and sometimes does not follow the changes in the power-law component.Our findings underscore the necessity of applying multiple analytic techniques to fully capture the multifaceted spectral variability of AGNs.
基金supported by the National Key R&D Program of China with grant No.2023YFA1608100supported by the National Natural Science Foundation of China(NSFC)under grant No.12273013+4 种基金support from the National Key R&D Program of China(grant Nos.2023YFA1607804,2022YFA1602902,and 2023YFA1607800)other NSFC projects(grant Nos.12120101003,12373010,12173051,and 12233008)the China Manned Space Project(No.CMS-CSST-2025-A06)the Strategic Priority Research Program of the Chinese Academy of Sciences with grant Nos.XDB0550100 and XDB0550000supported by the National Science Foundation under grant No.AST-2034437。
文摘Changing-look(CL)active galactic nuclei(AGNs)are an extremely rare type of AGNs,characterized by the appearance(turn-on)or disappearance(turn-off)of broad emission lines within months to years.We construct a sample of 211 CL AGN candidates by systematically searching the Sloan Digital Sky Survey spectra classified as GALAXY,but with the Zwicky Transient Facility and Near-Earth Object Wide-Field Infrared Explorer midinfrared light curves showing significant variability,at the redshift range from 0.1 to 0.75.To examine the success rate of this method,we cross-match the candidate sample with the Large Sky Area Multi-Object Fiber Spectroscopic Telescope and the Dark Energy Spectroscopic Instrument for repeat spectra,finding that the success rate of this method is 50%.By incorporating previously reported CL AGNs,a total of 48 CL AGNs have been identified within our sample,including two recurrent CL AGNs newly confirmed in this work.Our results suggest that the typical rest-frame timescale of CL behavior is from 1.7 to 18.1 yr,which is inconsistent with the obscuration model,and the Eddington ratios of CL AGNs are about 0.01 in the bright state.Additionally,our CL AGN sample follows the M_(BH)–σ_(*)relation of quiescent galaxies.In the future,we expect to detect more galaxies turning into Type 1 AGNs in this CL AGN candidate sample.
基金supported in part by the National SKA Program of China(No.2020SKA0110102)the National Natural Science Foundation of China(NSFC,Nos.12192220 and 12192223)the Youth Innovation Promotion Association of CAS(Y202064)。
文摘The feeding and feedback processes at the vicinity of a supermassive black hole(BH)are essential for our understanding of the connection between supermassive BH and its host galaxy.In this work,we provide a detailed investigation,both observational and theoretical,on the diffuse(~2"-20",~0.08-0.8 pc)X-ray emission around Sgr A*.Over two-decade Chandra observations are gathered to obtain highest signal-to-noise to date.We find that,the line center of iron lines of the outer 8"-18"region,ε_(c)=6.65+0.02-0.03 keV,is comparable to that(ε_(c)=6.60+0.05-0.03 keV)of the inner 2"-5"region.This is somewhat unexpected,since the gas temperature decreases further away from the central BH.Based on a dynamical inflow-outflow model that considers the gas feeding by stellar winds from Wolf-Rayet stars,we calculate the X-ray spectrum based on both the conventional collisional ionization equilibrium(CIE)assumption,and the newly developed non-equilibrium ionization(NEI)assumption.We find that,theoretically gases within~8"-10"remain in a CIE state,outside of this radius they will be in the NEI state.A comparison of the properties of~6.6 keV iron lines between CIE and NEI is addressed.Interestingly,the NEI interpretation of outer region is supported by the Chandra line center ε_(c) measurements of this region.
基金partially supported by the National Natural Science Foundation of China (11733001, U1531245, 10633010 and 11173009)Natural Science Foundation of Guangdong Province (2017A030313011)Astrophysics Key Subjects of Guangdong Province and Guangzhou City
文摘Active galactic nuclei(AGNs) can be divided into two major classes, namely radio-loud and radio-quiet AGNs. A small subset of the radio-loud AGNs is called blazars, which are believed to be unified with Fanaroff-Riley type Ⅰ/Ⅱ(FRI/Ⅱ) radio galaxies. Following our previous work(Fan et al.), we present a sample of 2400 sources with measured radio flux densities of the core and extended components. The sample contains 250 BL Lacs, 520 quasars, 175 Seyferts, 1178 galaxies, 153 FRI or FRⅡ galaxies and 104 unidentified sources. We then calculate the radio core-dominance parameters and spectral indices, and study their relationship. Our analysis shows that the core-dominance parameters and spectral indices are quite different for different types of sources. We also confirm that the correlation between core-dominance parameter and spectral index exists for a large sample presented in this work.
基金support of a grant from the John Templeton Foundation and the National Astronomical Observatories, Chinese Academy of Sciencesthe Subaru team and the National Natural Science Foundation of China (Grant No. 11890694)+1 种基金the National Natural Science Foundation of China (Grant Nos. 10173025, 10673013, 10778709, 11073031 and 11653005)the National Basic Research Program of China (973 Program, TG 2000077602)
文摘High resolution deep imaging from space and adaptive optics techniques with large ground-based facilities have enabled studies examining faint host galaxies of high redshift quasi-stellar objects (QSOs). However, the related image processing techniques, especially for a precise point-spread function (PSF) reconstruction and characterization of the host galaxy light profiles, have yet to be optimized. We present here the scientific performance of a principal component analysis (PCA) based PSF subtraction of the central bright point source of high redshift QSO images, as well as further characterization of the host galaxy profile by directly fitting a Sèrsic model to the residual image using the Markov Chain Monte Carlo (MCMC) algorithm. With a set of reference PSF star images which represent interleaving exposures between the QSO imaging, we can create an orthogonal basis of eigen-images and restore the PSF of QSO images by projecting the QSO images onto the basis. In this way, we can quantify the modes in which the PSF varies with time by a basis function that characterizes the temporal variations of the reference star as well as the QSO images. To verify the algorithm, we performed a simulation and applied this method to one of the high-z QSO targets from Mechtley et al. We demonstrate that the PCA-based PSF subtraction and further modeling of the galaxy’s light profile using MCMC fitting would sufficiently remove the effects from central dominating point sources, and improve characterization ability for the host galaxies of high-z QSOs to the background noise level which is much better than previous two-component fitting procedures.
基金supported by the National SKA Program of China(2022SKA0120101,2022SKA0130100,2022SKA 0130104)the National Natural Science Foundation of China(NSFC,grant No.12103013)+5 种基金the Foundation of Science and Technology of Guizhou Province(Nos.(2021)023)the Foundation of Guizhou Provincial Education Department(Nos.KY(2021)303,KY(2020)003,KY(2023)059)supported by the National Natural Science Foundation of China(NSFC,grant Nos.12103076 and 12233005)the National Key R&D Program of China(2020YFE0202100)the Shanghai Sailing Program(21YF1455300)the China Postdoctoral Science Foundation(2021M693267)。
文摘We present an independent catalog(FRIIRGcat)of 45,241 Fanaroff–Riley TypeⅡ(FR-Ⅱ)radio galaxies compiled from the Very Large Array Faint Images of the Radio Sky at Twenty-centimeters(FIRST)survey and employed the deep learning method.Among them,optical and/or infrared counterparts are identified for 41,425 FR-Ⅱs.This catalog spans luminosities 2.63×10^(22)≤L_(rad)≤6.76×10^(29)W Hz^(-1)and redshifts up to z=5.01.The spectroscopic classification indicates that there are 1431 low-excitation radio galaxies and 260 high-excitation radio galaxies.Among the spectroscopically identified sources,black hole masses are estimated for 4837 FR-Is,which are in 10^(7.5)■M_(BH)■10^(9.5)M_(⊙).Interestingly,this catalog reveals a couple of giant radio galaxies(GRGs),which are already in the existing GRG catalog,confirming the efficiency of this FR-I catalog.Furthermore,284new GRGs are unveiled in this new FR-I sample;they have the largest projected sizes ranging from 701 to1209 kpc and are located at redshifts 0.31<z<2.42.Finally,we explore the distribution of the jet position angle and it shows that the faint Images of the FIRST images are significantly affected by the systematic effect(the observing beams).The method presented in this work is expected to be applicable to the radio sky surveys that are currently being conducted because they have finely refined telescope arrays.On the other hand,we are expecting that further new methods will be dedicated to solving this problem.
基金financial support from the National Natural Science Foundation of China(NSFC,No.12203028)supported by the research project of Qujing Normal University(2105098001/094)+4 种基金supported by the youth project of Yunnan Provincial Science and Technology Department(202101AU070146,2103010006)funding for the training Program for talents in Xingdian,Yunnan Provincesupported by the NSFC(12121003,12192220,and 12192222)the science research grants from the China Manned Space Project with No.CMS-CSST-2021-A05supported by the NSFC(11733001,U2031201 and 12433004)。
文摘The theoretical model suggests that relativistic jets of active galactic nuclei(AGNs)rely on the black hole spin and/or accretion.We study the relationship between jet,accretion,and spin using supermassive black hole samples with reliable spin of black holes.Our results are as follows:(1)There is a weak correlation between radio luminosity and the spin of the black hole for our sample,which may imply that the jet of the supermassive black hole in our sample depends on the other physical parameters besides black hole spins,such as accretion disk luminosity.(2)The jet power of a supermassive black hole can be explained by the hybrid model with magnetic field of corona.(3)There is a significant correlation between radio-loudness and black hole spin for our sample.These sources with high radio-loudness tend to have high black hole spins.These results provide observational evidence that the black hole spin may explain the bimodal phenomena of radio-loud and radio-quiet AGNs.
基金Project supported by the National Science Foundation for Distinguished Young Scholars of China (Grant No 10125313)the National Natural Science Foundation of China (Grant Nos 10573005 and 10633010)
文摘In this paper, we use a method to dctermine some basic parameters for the γ-ray loud blazars. The parameters include the central black mass （M）, the boosting factor （δ）, the propagation angle （Ф）, the distance along the axis to the site of the γ-ray production （d）. A sample including 32 γ-ray loud blazars with available variability time scales has been used to discuss the above properties. In this method, the γ-ray energy, the emission size and the property of the accretion disc determine the absorption effect. If we take the intrinsic γ-ray luminosity to be λ times the Eddington luminosity, i.e. Lγ^in =λLEdd, then we have the following results： the mass of the black hole is in the range of （0.59 - 67.99） ×10^7M⊙ （λ = 1.0） or （0.90 - 104.13） × 10^7M⊙ （λ = 0.1）; the boosting factor （5） in the range of 0.16 - 2.09（λ = 1.0） or 0.24 - 2.86 （λ = 0.1）; the angle （Ф） in the range of 9.53°- 73.85° （λ =1.0） or 7.36° - 68.89° （λ = 0.1）; and the distance （d/Rg） in the range of 22.39 - 609.36 （λ = 1.0） or 17.54 - 541.88 （λ = 0.1）.
基金the financial support from the Council of Scientific&Industrial Research (CSIR),Government of India。
文摘We use the recently discovered simple photometric parameter Central Intensity Ratio(CIR)determined for a sample of 57 nearby(z<0.02)Seyfert galaxies to explore the central features of galaxies and their possible connection with galaxy evolution.The sample of galaxies shows strong anti-correlation between CIR and mass of their central supermassive black holes(SMBHs).The SMBH masses of ellipticals are systematically higher for a given CIR value than those for lenticulars and spirals in the sample.However,the correlation between CIR and central velocity dispersion is weak.CIR appears less influenced by the excess flux produced by the central engine in these galaxies,when compared to spectroscopic parameters like velocity dispersion and OⅣflux,and proves to be a fast and reliable tool for estimating central SMBH mass.
基金supported by the National Natural Science Foundation of China(grants 12022305,11973050,and 12203022)。
文摘Theγ-ray emitting compact symmetric objects(CSOs)PKS 1718-649,NGC 3894,and TXS 0128+554 are lobedominated in the radio emission.In order to investigate theirγ-ray radiation properties,we analyze the~14yr Fermi/LAT observation data of the three CSOs.They all show the low luminosity(1041-1043 erg s-1)and no significant variability in theγ-ray band.Theirγ-ray average spectra can be well fitted by a power-law function.These properties ofγ-rays are clearly different from theγ-ray emitting CSOs CTD 135 and PKS 1413+135,for which theγ-rays are produced by a restarted aligned jet.In the L_(γ)-Γ_(γ)plane,the three CSOs are also located at the region occupied by radio galaxies(RGs)while CTD 135 and PKS 1413+135 display a similar feature to blazars.Together with a similar radio emission property toγ-ray emitting RGs Cen A and Fornax A,we speculate that theγ-rays of the three CSOs stem from their extended mini-lobes.The broadband spectral energy distributions of the three CSOs can be well explained by the two-zone leptonic model,where theirγ-rays are produced by the inverse Compton process of the relativistic electrons in extended regions.By extrapolating the observed Fermi/LAT spectra to the very high energy band,we find that TXS 0128+554 among the three CSOs may be detected by the Cherenkov Telescope Array in the future.
基金support from the Infosys Foundation through the Young Investigator grantthe Alexander von-Humboldt Foundation for financial support
文摘Giant gaseous layers(termed“superdisks”)have been hypothesized in the past to account for the strip-like radio emission gap(or straight-edged central brightness depression)observed between twin radio lobes,in over a dozen relatively nearby powerful Fanaroff-Riley Class II radio galaxies.They could also provide a plausible alternative explanation for a range of observations.Although a number of explanations have been proposed for the origin of the superdisks,little is known about their material content.Some X-ray observations of superdisk candidates indicate the presence of hot gas,but a cool dusty medium also seems to be common.If they are entirely or partly composed of neutral gas,then it may be directly detectable and we report here a first attempt to detect/image any neutral hydrogen gas present in the superdisks that are inferred to be present in four nearby radio galaxies.We have not found a positive H I signal in any of the four sources,resulting in tight upper limits on the H I number density in the postulated superdisks,estimated directly from the central rms noise values of the final radio continuum subtracted image.The estimated ranges of the upper limit on neutral hydrogen number density and column density are 10^-4-10^-3 atoms per cm3 and 10^19-10^20 atoms per cm^2,respectively.No positive H I signal is detected even after combining all the four available H I images(with inverse variance weighting).This clearly rules out an H I dominated superdisk as a viable model to explain these structures,however,the possibility of a superdisk being composed of warm/hot gas still remains open.
基金Supported by the National Natural Science Foundation of China under No.19973014the National Climbing program of Chinathe National 973 Project of China(NKBRSF G19990754)
文摘In previous paper we have shown that the soft X-ray spectra of two types of Seyfert 1 galaxies behave statistically differently with increasing intensity. In order to see how the spectrum of blazars changes, we made plots of Hardness Ratio 1 versus Count Rates (HR1-Cts) for 18 blazars observed by ROSAT/PSPC. According to our criteria, ten showed a positive HR1-Cts correlation, two a negative correlation, and the remaining six, no clear correlation. Thus, most blazars of our sample show a hardening spectrum during overall flux increase, though some vary randomly. By investigating the photon index of these objects and different radiation theories, we argue that relative dominance between the synchrotron and inverse Compton emission in the soft X-ray band can well account for the differing spectral behaviours and that the different spectral variations might represent a sequence of synchrotron peaked frequency.
文摘It has long remained an open question as to the geometry of the broad line region(BLR)in active galactic nuclei(AGNs).The reverberation mapping technique which measures the response of the broad emission lines to the ionizing continuum,when combined with multiwavelength continuum fitted by sophisticated accretion disks,provides a way of probing the BLR geometry.We analyze a sample of 35 AGNs,which have been monitored by the reverberation mapping campaign.In view of energy budget,the reverberation-based BH masses are found to be in agreement with those obtained by accretion disk models in two thirds of the present sample while the reverberation mapping methods underestimate the BH masses in about one third of objects,as also suggested by CoUin et al.in a recent work.We point out that there are obviously two kinds of BLR geometry,which are strongly dependent on the Eddington ratio,and separated by the value LBol/LEdd-0.1.These results prefer a scenario of the disk and wind configuration of the BLR and identify the Eddington ratio as the physical driver regulating the wind in the BLR.
基金supported by the National Natural Science Foundation of China(Distinguished Young Scholars,Grant Nos.10425313,10833006 and 10621303)Chinese Academy of Sciences’Hundred Talent Program973 project of the Ministry of Science and Technology of China(GrantNo.2007CB815406)
文摘We present our initial results from a study of 14 （U）LIRGs with a doublenucleus （z 〈0.15） and an AGN signature in the Chandra archive.The goals of our study are to search for more possible cases of binary AGNs and to investigate the X-ray properties and energy sources of these energetic objects,a major effort devoted specifically to searching for binary AGNs from （U）LIRGs.Our studies suggest that Mrk 266 might be a new candidate in hosting binary AGNs supported by X-ray observations.Our analysis shows that most （U）LIRGs are essentially weak X-ray sources and are not dominated by AGNs,due to both the lack of Fe K line detections and weak emission in the hard X-ray band.We find evidence for thermal emission with temperature kT ～ 0.7keV in seven nuclear regions,and this component is possibly associated with the nuclear or circumnuclear starburst.The soft and hard X-ray to far-infrared ratios also suggest that most （U）LIRGs are not energetically dominated by AGNs.Therefore,this study only provides one additional candidate of binary AGNs.We cannot rule out the existence of low luminosity AGNs and thus binary AGNs in all of them,particularly,those highly obscured and spatially unresolved systems.Nine of 14 （U）LIRGs,including three previously known binary AGNs and a new candidate Mrk 266,clearly have obvious X-ray counterparts to their double optical/near-IR nuclei.whereas only two out of 14 have one obvious X-ray counterpart detected.Additionally,Arp 220 and Mrk 273 are not spatially resolved owing to their small nuclear separations （～ 1″）,and no
基金Supported by the National Natural Science Foundation of China.
文摘There is observational evidence that broad-line regions （BLRs） exist in most active galactic nuclei （AGNs）, but their origin is still unclear. One scenario is that the BLRs originate from winds accelerated from the hot coronae of the disks, and the winds are suppressed when the black hole is accreting at low rates. This model predicts a relation between rh （m ~ /~f//~fEdd） and the FWHM of broad emission lines. We estimate the central black hole masses for a sample of bright AGNs by using their broad Hβ line-widths and optical luminosities. The dimensionless accretion rates rh = M/MEdd are derived from the optical continuum luminosities by using two different models： using an empirical relation between the bolometric luminosity Lbol and the optical luminosity （rh = Lbol/LEdd, a fixed radiative efficiency is adopted）; and calculating the optical spectra of accretion disks as a function of rh. We find a slgmficant correlation between the denved of and the observed line width of Hβ, FWHMα m^-0.aT, which almost overlaps the disk-corona model calculations, if the viscosity a α≈ 0.1 - 0.2 is adopted. Our results provide strong evidence for the physical link between the BLRs and accretion disks in AGNs.
文摘Inertial mass is detected on Earth only when matter is accelerated or decelerated. Recently evidence has been reported for a low-level velocity oscillation with a period of 39 ± 1 Mpc (127 ± 3 Myr) superimposed on the Hubble flow. Like the Hubble flow, this oscillation is assumed to be an expansion and contraction of space itself. If space is oscillating as it expands and the Hubble flow contains a superimposed velocity ripple, matter on Earth will experience alternating accelerations and decelerations relative to the rest of the matter in the Universe. The acceleration curve can be obtained from the velocity oscillation curve simply by taking the magnitude of the derivative of the velocity curve and the acceleration curve is found here to have a period of 63.5 ± 1.5 Myr. Evidence has also been claimed recently for a ubiquitous ~62 ± 3 Myr periodic fluctuation superimposed on general trends in the fossil biodiversity on Earth. The periods of the acceleration curve oscillation and fossil biodiversity fluctuations are thus identical within the errors. A second, weaker fluctuation is also detected in both the Hubble flow and fossil biodiversity trends. They too have identical periods of ~140 Myr. From this excellent agreement, it is argued here that it is the oscillation in the Hubble flow, through an inertia-like phenomenon involving all the matter in the universe that has produced the fluctuations in the fossil biodiversity on Earth. This may represent the first instance where observational evidence supporting Mach’s Principle of Inertia has been found.
文摘According to the standard model, an active galactic nucleus (AGN) consists of an inner accretion disk with a jet around a central massive black hole, and a number of outer broad line regions (BLRs) and narrow line regions (NLRs). The geometrical relationship between the BLRs and the accretion disk is not well understood. Assuming the motion of the BLRs is virialized and its configuration is disk-like, we derived its inclination to the line of sight for a sample of AGNs from their bulge stellar velocity dispersion, their size of the BLRs and their Hβ linewidth. Compared with the inclination of the accretion disk obtained from the X-ray Fe Kα emission lines, we found that there is no positive correlation between the two. Our results showed that BLRs are not coplanar with the accretion disk and that we should be cautious of using the BLRs inclination as the disk inclination. The non-coplanar geometry of the outer BLRs and the inner accretion disk provides clues to the origin of BLRs and the properties of the accretion disk. Our preferable interpretation is that BLRs arise out of the outer part of a warped accretion disk.
基金supported by the National 973 project(NKBRSF G19990754)the National Science Fund for Distinguished Young Scholars(10125313)+1 种基金the Fund for Top Scholars of Guangdong Province(Q02114)supported by the Argentine agencies CONICET and ANPCT(PICT No.03-13291).|
文摘The relativistic beaming model has been successfully used to explain many of the observational properties of active galactic nuclei. In this model the total emission is formed by two components, one beamed, one unbeamed. However, the exact contribution from each component in unresolved sources is still not clear. In the radio band, the core and extended emissions are clearly separated. We adopt the method proposed by Kembhavi to separate the two contributions in the X-ray emissions in a sample of 19 gamma-ray loud blazars. It is clearly shown that the beamed emission dominates the X-ray flux and the unbeamed X-ray emission is correlated with the extended radio emission of the considered objects. We also find that the ratio of the beamed to the unbeamed X-ray luminosity is correlated with the X-ray spectral index, an effect that should be a consequence of the underlying X-ray emission mechanism.
