The second catalog of active galactic nuclei (AGNs) detected by the Fermi Large Area Telescope (LAT) in two years of scientific operation is presented. The second LAT AGN catalog (2LAC) includes 1017 {gamma}-ray sources located at high Galactic latitudes (|b|>10{deg}) that are detected with a test statistic (TS) greater than 25 and associated statistically with AGNs. However, some of these are affected by analysis issues and some are associated with multiple AGNs. Consequently, we define a Clean Sample which includes 886 AGNs, comprising 395 BL Lacertae objects (BL Lac objects), 310 flat-spectrum radio quasars (FSRQs), 157 candidate blazars of unknown type (i.e., with broadband blazar characteristics but with no optical spectral measurement yet), 8 misaligned AGNs, 4 narrow-line Seyfert 1 (NLS1s), 10 AGNs of other types, and 2 starburst galaxies. Where possible, the blazars have been further classified based on their spectral energy distributions (SEDs) as archival radio, optical, and X-ray data permit. While almost all FSRQs have a synchrotron-peak frequency <10^14^Hz, about half of the BL Lac objects have a synchrotron-peak frequency >10^15^Hz. The 2LAC represents a significant improvement relative to the first LAT AGN catalog (1LAC), with 52% more associated sources. The full characterization of the newly detected sources will require more broadband data. Various properties, such as {gamma}-ray fluxes and photon power-law spectral indices, redshifts, {gamma}-ray luminosities, variability, and archival radio luminosities and their correlations are presented and discussed for the different blazar classes. The general trends observed in 1LAC are confirmed.
The Lick AGN Monitoring Project targeted 13 nearby Seyfert 1 galaxies with the intent of measuring the masses of their central black holes using reverberation mapping. The sample includes 12 galaxies selected to have black holes with masses roughly in the range 10^6^-10^7^M_{sun}_, as well as the well-studied active galactic nucleus (AGN) NGC 5548. In conjunction with a spectroscopic monitoring campaign, we obtained broadband B and V images on most nights from 2008 February through 2008 May. The imaging observations were carried out by four telescopes: the 0.76m Katzman Automatic Imaging Telescope, the 2m Multicolor Active Galactic Nuclei Monitoring telescope, the Palomar 60 inch (1.5m) telescope, and the 0.80m Tenagra II telescope. Having well-sampled light curves over the course of a few months is useful for obtaining the broad-line reverberation lag and black hole mass, and also allows us to examine the characteristics of the continuum variability. In this paper, we discuss the observational methods and the photometric measurements, and present the AGN continuum light curves. We measure various variability characteristics of each of the light curves. We do not detect any evidence for a time lag between the B- and V-band variations, and we do not find significant color variations for the AGNs in our sample.
We present data from a moderately deep spectroscopic Schmidt survey (B_lim_=17.5) of "active galaxies" selected by the presence of emission lines in their spectra and/or their UV excess. 92 emission line objects have been found in two adjacent fields (approximately 50deg^2^) in the direction of the southern extension of the Virgo cluster. We give a catalog containing positions, photographic R and B magnitudes, U-R colors, effective diameters, redshifts, equivalent widths and intensity ratios of the [OIII]{lambda}{lambda}4959,5007, H{beta} and [OII]{lambda}3727 emission lines. On these fields, we evaluate the completeness limit of the survey at a pseudo B magnitude values of 15.7. A more elaborate astrophysical analysis will appear in a forthcoming paper.
We create a baseline of the black hole (BH) mass (M_BH_)-stellar-velocity dispersion ({sigma}) relation for active galaxies, using a sample of 66 local (0.02<z<0.09) Seyfert-1 galaxies, selected from the Sloan Digital Sky Survey (SDSS). Analysis of SDSS images yields AGN luminosities free of host-galaxy contamination, and morphological classification. 51/66 galaxies have spiral morphology. Out of these, 28 bulges have Sersic index n<2 and are considered candidate pseudo-bulges, with eight being definite pseudo-bulges based on multiple classification criteria met. Only 4/66 galaxies show signs of interaction/merging. High signal-to-noise ratio Keck spectra provide the width of the broad H{beta} emission line free of Fe II emission and stellar absorption. AGN luminosity and H{beta} line widths are used to estimate M_BH_. The Keck-based spatially resolved kinematics is used to determine stellar-velocity dispersion within the spheroid effective radius ({sigma}_spat,reff_). We find that {sigma} can vary on average by up to 40% across definitions commonly used in the literature, emphasizing the importance of using self-consistent definitions in comparisons and evolutionary studies. The M_BH_-{sigma} relation for our Seyfert-1 galaxy sample has the same intercept and scatter as that of reverberation-mapped AGNs as well as that of quiescent galaxies, consistent with the hypothesis that our single epoch M_BH_ estimator and sample selection function do not introduce significant biases. Barred galaxies, merging galaxies, and those hosting pseudo-bulges do not represent outliers in the M_BH_-{sigma} relation. This is in contrast with previous work, although no firm conclusion can be drawn on this matter due to the small sample size and limited resolution of the SDSS images.
Observations of H_2_O masers from circumnuclear disks in active galaxies for the Megamaser Cosmology Project (MCP) allow accurate measurement of the mass of supermassive black holes (BH) in these galaxies. We present the Very Long Baseline Interferometry images and kinematics of water maser emission in six active galaxies: NGC 1194, NGC 2273, NGC 2960 (Mrk 1419), NGC 4388, NGC 6264 and NGC 6323. We use the Keplerian rotation curves of these six megamaser galaxies, plus a seventh previously published, to determine accurate enclosed masses within the central ~0.3pc of these galaxies, smaller than the radius of the sphere of influence of the central mass in all cases.
As part of the Megamaser Cosmology Project, we present VLBI maps of nuclear water masers toward five galaxies. The masers originate in sub-parsec circumnuclear disks. For three of the galaxies, we fit Keplerian rotation curves to estimate their supermassive black hole (SMBH) masses, and determine (2.9+/-0.3)x10^6^M_{sun}_ for J0437+2456, (1.7+/-0.1)x10^7^M_{sun}_ for ESO 558-G009, and (1.1+/-0.2)x10^7^M_{sun}_ for NGC 5495. In the other two galaxies, Mrk 1029 and NGC 1320, the geometry and dynamics are more complicated and preclude robust black hole mass estimates. Including our new results, we compiled a list of 15 VLBI-confirmed disk maser galaxies with robust SMBH mass measurements. With this sample, we confirm the empirical relation of R_out_{propto}0.3M_SMBH_ reported in Wardle & Yusef-Zadeh (2012ApJ...750L..38W). We also find a tentative correlation between maser disk outer radii and Wide-Field Infrared Survey Explorer luminosity. We find no correlations of maser disk size with X-ray 2-10keV luminosity or [OIII] luminosity.
We present high-resolution (submas) Very Long Baseline Interferometry maps of nuclear H_2_O megamasers for seven galaxies. In UGC 6093, the well-aligned systemic masers and high-velocity masers originate in an edge-on, flat disk and we determine the mass of the central supermassive black holes (SMBH) to be M_SMBH_=2.58x10^7^M_{sun}_ (+/-7%). For J1346+5228, the distribution of masers is consistent with a disk, but the faint high-velocity masers are only marginally detected, and we constrain the mass of the SMBH to be in the range (1.5-2.0)x10^7^M_{sun}_. The origin of the masers in Mrk 1210 is less clear, as the systemic and high-velocity masers are misaligned and show a disorganized velocity structure. We present one possible model in which the masers originate in a tilted, warped disk, but we do not rule out the possibility of other explanations including outflow masers. In NGC 6926, we detect a set of redshifted masers, clustered within a parsec of each other, and a single blueshifted maser about 4.4pc away, an offset that would be unusually large for a maser disk system. Nevertheless, if it is a disk system, we estimate the enclosed mass to be M_SMBH_<4.8x10^7^M_{sun}_. For NGC 5793, we detect redshifted masers spaced about 1.4pc from a clustered set of blueshifted features. The orientation of the structure supports a disk scenario as suggested by Hagiwara+ (2001ApJ...560..119H). We estimate the enclosed mass to be M_SMBH_<1.3x10^7^M_{sun}_. For NGC 2824 and J0350-0127, the masers may be associated with parsec- or subparsec-scale jets or outflows.
This is a compendium of 452,794 type-I QSOs and AGN, largely complete from the literature to 21 June 2016. Also included are ~900K high-confidence quasar candidates from SDSS-based photometric quasar catalogs (of 90%+ likelihood) and from all-sky radio/X-ray associated objects (of 80%+ likelihood). Type-II and Bl Lac objects are also included, bringing the total count to 1,422,219. This version is the same as v4.8 but with these changes: (1) The 3XMM-DR6 X-ray source catalog (www.cosmos.esa.int/web/xmm-newton/xsa) has been added and new X-ray associations calculated. (2) Radio/X-ray data have been reprocessed in line with that of the new Million Optical Radio/X-ray (MORX) associations catalogue, in preparation. The catalog format is simple, each object is shown as one line bearing the J2000 coordinates, its original name, object class, red and blue optical magnitudes, PSF class, redshift, the citations for the name and redshift, plus up to four radio/X-ray identifiers where applicable. Questions/comments/praise/complaints may be directed to Eric Flesch at eric(at)flesch.org.
This is a compendium of 623,004 type-I QSOs and AGN, largely complete from the literature to 15 June 2019 including SDSS-DR15 and LAMOST QSO DR5. Also included are approx 1.32M high-confidence (80%+ likelihood) quasar candidates from the NBCKDE, NBCKDE-v3, AllWISE, XDQSO & Peters photometric quasar catalogs (citations in Note 7 below) and from all-sky radio/X-ray associated objects which are calculated here. Type-II and Bl Lac objects are also included, plus galaxies with double radio lobes, bringing the total count to 1,986,800. Gaia-DR2 astrometry is used where available, amounting to ~63% of all objects. Changes from version 6.2 are: (1) Quasars added from publications to 15 June 2019, including 4LAC. (2) 3581 galaxies with double radio lobes are added as type=G because the lobes show that they have active nuclei of some kind, even if well hidden. (3) Positional fixes of a few arcsec were done for ~50 legacy objects. (4) Blazar candidates with neither redshift nor radio/X-ray association, about 30 objects, are dropped. Most were stated low confidence in legacy papers. Low-confidence/quality or questionable objects (so deemed by their researchers) are not included in Milliquas. Additional quality cuts can be applied as detailed in Flesch 2015,PASA,32,10. The aim here is to present one unique reliable object per each data row. The catalog format is simple, each object is shown as one line bearing the J2000 coordinates, its original name, object class, red and blue optical magnitudes, PSF class, redshift, the citations for the name and redshift, plus up to four radio/X-ray identifiers where applicable. This catalog can be cited as Milliquas v6.3 2019 update, Flesch E., 2015PASA...32...10F was the published version of this catalog as at 2015. Questions/comments/praise/complaints may be directed to me at eric(at)flesch.org.
The Million Quasars (Milliquas) catalogue, version 7.2
Short Name:
VII/290
Date:
21 Oct 2021
Publisher:
CDS
Description:
This is a compendium of 829666 type-I QSOs and AGN, largely complete from the literature to 30 April 2021 including SDSS-DR16 quasars and VLASS radio. Also included are 703348 candidates which are calculated as 60%-100% likely to be quasars, including 225051 which are radio/X-ray associated. Type-II and Bl Lac objects are also included, bringing the total count to 1573824. Gaia-DR2 astrometry is used where available, amounting to ~66% of all objects. Changes from version 7.1 are: (1) Quasars added from publications to 30 April 2021. (2) The VLASS Quick Look radio catalog is included, which adds 34189 new radio core associations and 6793 probable double radio lobe associations. (3) Ongoing audits of SDSS & LAMOST quasars have led to a few additions & drops. Some WISEA-supported SDSS/LAMOST pipeline quasars are now accepted which were otherwise marginal. Also some likely galaxies removed. Low-confidence/quality or questionable objects (so deemed by their researchers) are not included in Milliquas. Additional quality cuts can apply as detailed in the HMQ paper (Flesch, 2015PASA...32...10F). Full QSO/AGN classification is via spectral lines, thus hidden / occluded objects may be absent from Milliquas. Two NIQs offset <2-arcsecs can be reported as a single object if within the same host. The aim here is to present one unique reliable object per each data row. The catalog format is simple, each object is shown as one line bearing the J2000 coordinates, its original name, object class, red and blue optical magnitudes, PSF class, redshift, the citations for the name and redshift, plus up to four radio/X-ray identifiers where applicable. Please cite as Milliquas v7.2, Flesch, E.W. 2021, arXiv:2105.12985 or as Milliquas v7.2 (2021) update, Flesch, E.W. 2015PASA...32...10F. Questions/comments/praise/complaints may be directed to me at eric(at)flesch.org.
