A Machine Learning Made Catalog of FR-Ⅱ Radio Galaxies from the FIRST Survey

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.

Lobe-dominatedγ-Ray Emission of Compact Symmetric Objects

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.

Study of Central Intensity Ratio of Seyfert Galaxies in Nearby Universe

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.

Does Diffuse Circumnuclear Gas around Sgr A^(*) Achieve Collisional Ionization Equilibrium or Remain Non-equilibrium Ionization?

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.

The relationship between the radio core-dominance parameter and spectral index in different classes of extragalactic radio sources(Ⅱ)

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.

Decomposing the host galaxy from high-z QSOs using principal component analysis

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.

Central black hole mass determination for blazars

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）.

Chandra archival study of (U)LIRGs with a double nucleus:binary AGNs?

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

Variability of Soft X-ray Spectral Shape in Blazars Observed by ROSAT

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.

Evidence of the Link between Broad Emission Line Regions and Accretion Disks in Active Galactic Nuclei

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.

Mach’s Principle of Inertia Is Supported by Recent Astronomical Evidence

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.

The Relation between the Inclinations of Broad Line Regions and the Accretion Disk

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.

Separation of Different Contributions to the Total X-ray Luminosity in Gamma-ray Loud Blazars

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.