- ID:
- ivo://CDS.VizieR/J/ApJS/184/218
- Title:
- The zCOSMOS 10k-bright spectroscopic sample
- Short Name:
- J/ApJS/184/218
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present spectroscopic redshifts of a large sample of galaxies with I_AB_<22.5 in the COSMOS field, measured from spectra of 10644 objects that have been obtained in the first two years of observations in the zCOSMOS-bright redshift survey. These include a statistically complete subset of 10109 objects. The average accuracy of individual redshifts is 110km/s, independent of redshift. The reliability of individual redshifts is described by a Confidence Class that has been empirically calibrated through repeat spectroscopic observations of over 600 galaxies. There is very good agreement between spectroscopic and photometric redshifts for the most secure Confidence Classes. For the less secure Confidence Classes, there is a good correspondence between the fraction of objects with a consistent photometric redshift and the spectroscopic repeatability, suggesting that the photometric redshifts can be used to indicate which of the less secure spectroscopic redshifts are likely right and which are probably wrong, and to give an indication of the nature of objects for which we failed to determine a redshift. Using this approach, we can construct a spectroscopic sample that is 99% reliable and which is 88% complete in the sample as a whole, and 95% complete in the redshift range 0.5<z<0.8. The luminosity and mass completeness levels of the zCOSMOS-bright sample of galaxies is also discussed.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/810/14
- Title:
- Third catalog of LAT-detected AGNs (3LAC)
- Short Name:
- J/ApJ/810/14
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The third catalog of active galactic nuclei (AGNs) detected by the Fermi-LAT (3LAC) is presented. It is based on the third Fermi-LAT catalog (3FGL) of sources detected between 100MeV and 300GeV with a Test Statistic greater than 25, between 2008 August 4 and 2012 July 31. The 3LAC includes 1591 AGNs located at high Galactic latitudes (|b|>10{deg}), a 71% increase over the second catalog based on 2 years of data. There are 28 duplicate associations, thus 1563 of the 2192 high-latitude gamma-ray sources of the 3FGL catalog are AGNs. Most of them (98%) are blazars. About half of the newly detected blazars are of unknown type, i.e., they lack spectroscopic information of sufficient quality to determine the strength of their emission lines. Based on their gamma-ray spectral properties, these sources are evenly split between flat-spectrum radio quasars (FSRQs) and BL Lacs. The most abundant detected BL Lacs are of the high-synchrotron-peaked (HSP) type. About 50% of the BL Lacs have no measured redshifts. A few new rare outliers (HSP-FSRQs and high-luminosity HSP BL Lacs) are reported. The general properties of the 3LAC sample confirm previous findings from earlier catalogs. The fraction of 3LAC blazars in the total population of blazars listed in BZCAT remains non-negligible even at the faint ends of the BZCAT-blazar radio, optical, and X-ray flux distributions, which hints that even the faintest known blazars could eventually shine in gamma-rays at LAT-detection levels. The energy-flux distributions of the different blazar populations are in good agreement with extrapolation from earlier catalogs.
- ID:
- ivo://CDS.VizieR/J/ApJ/841/37
- Title:
- Tori in AGNs through Spitzer/IRS spectra
- Short Name:
- J/ApJ/841/37
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Several authors have claimed that less luminous active galactic nuclei (AGNs) are not capable of sustaining a dusty torus structure. Thus, a gradual resizing of the torus is expected when the AGN luminosity decreases. Our aim is to examine mid-infrared observations of local AGNs of different luminosities for the gradual resizing and disappearance of the torus. We applied the decomposition method described by Hernan-Caballero+ (2015, J/ApJ/803/109) to a sample of ~100 Spitzer/IRS spectra of low-luminosity AGNs and powerful Seyferts in order to decontaminate the torus component from other contributors. We have also included Starburst objects to ensure secure decomposition of the Spitzer/IRS spectra. We have used the affinity propagation (AP) method to cluster the data into five groups within the sample according to torus contribution to the 5-15{mu}m range (C_torus_) and bolometric luminosity (L_bol_).
- ID:
- ivo://CDS.VizieR/J/ApJS/242/4
- Title:
- Two new catalogs of blazar candidates
- Short Name:
- J/ApJS/242/4
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present two catalogs of radio-loud candidate blazars whose Wide-Field Infrared Survey Explorer (WISE) mid-infrared colors are selected to be consistent with the colors of confirmed {gamma}-ray-emitting blazars. The first catalog is the improved and expanded release of the WISE Blazar-like Radio-Loud Sources (WIBRaLS) catalog presented by D'Abrusco et al. It includes sources detected in all four WISE filters, spatially cross-matched with radio sources in one of three radio surveys and radio-loud based on their q_22_ spectral parameter. WIBRaLS2 includes 9541 sources classified as BL Lacs, flat-spectrum radio quasars, or mixed candidates based on their WISE colors. The second catalog, called KDEBLLACS, based on a new selection technique, contains 5579 candidate BL Lacs extracted from the population of WISE sources detected in the first three WISE passbands ([3.4], [4.6], and [12]) only, whose mid-infrared colors are similar to those of confirmed, {gamma}-ray BL Lacs. Members of KDBLLACS are also required to have a radio counterpart and be radio-loud based on the parameter q_12_, defined similarly to the q_22_ used for the WIBRaLS2. We describe the properties of these catalogs and compare them with the largest samples of confirmed and candidate blazars in the literature. We cross-match the two new catalogs with the most recent catalogs of {gamma}-ray sources detected by the Fermi Large Area Telescope. Since spectroscopic observations of candidate blazars from the first WIBRaLS catalog within the uncertainty regions of {gamma}-ray unassociated sources confirmed that ~90% of these candidates are blazars, we anticipate that these new catalogs will again play an important role in the identification of the {gamma}-ray sky.
- ID:
- ivo://CDS.VizieR/J/MNRAS/426/2703
- Title:
- Type 1 AGN at low z. II.
- Short Name:
- J/MNRAS/426/2703
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore the relative strength of the narrow emission lines in a Sloan Digital Sky Survey based sample of broad H{alpha} selected active galactic nuclei (AGN), defined in Paper I (Stern & Laor, 2010, Cat. J/MNRAS/423/600).
- ID:
- ivo://CDS.VizieR/J/MNRAS/431/836
- Title:
- Type 1 AGN at low z. III.
- Short Name:
- J/MNRAS/431/836
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the optical narrow-line ratios in a Sloan Digital Sky Survey (SDSS) based sample of 3175 broad H{alpha} selected type 1 active galactic nuclei (AGN), and explore their positions in the BPT diagrams as a function of the AGN and the host properties. We find the following: (1) the luminosities of all measured narrow lines (H{alpha}, H{beta}, [OIII], [NII], [SII], [OI]) show a Baldwin relation relative to the broad H{alpha} luminosity LbH{alpha}, with slopes in the range of 0.53-0.72. (2) About 20 percent of the type 1 AGN reside within the "Composite" and "star-forming" (SF) regions of the Baldwin, Phillips & Terlevich (BPT) diagrams. These objects also show excess narrow H{alpha} and ultraviolet (UV) luminosities, for their LbH{alpha}, consistent with contribution from star formation which dominates the narrow-lines emission, as expected from their positions in the BPT diagrams. (3) The type 1 which reside within the AGN region in the BPT diagrams, are offset to lower [SII]/H{alpha} and [NII]/H{alpha} luminosity ratios, compared to type 2 AGN. This offset is a selection effect, related to the lower AGN/host luminosity selection of the type 2 AGN selected from the SDSS galaxy sample. (4) The [NII]/H{alpha} and [NII]/[SII] ratios in type 1 AGN increase with the host mass, as expected if the mass-metallicity relation of quiescent galaxies holds for the AGN narrow-line region (NLR). (5) The broad lines optical Fe ii is higher for a higher [NII]/H{alpha}, at a fixed Lbol and Eddington ratio L/LEdd. This suggests that the broad line region metallicity is also related to the host mass. (6) The fraction of AGN which are low-ionization nuclear emission-line regions (LINERs) increases sharply with decreasing L/LEdd. This fraction is the same for type 1 and type 2 AGN. (7) The BPT position is unaffected by the amount of dust extinction of the optical-UV continuum, which suggests that the extincting dust resides on scales larger than the narrow-line region (NLR).
- ID:
- ivo://CDS.VizieR/J/ApJ/841/102
- Title:
- Type 2 AGN host galaxies in Chandra-COSMOS
- Short Name:
- J/ApJ/841/102
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We investigate the star formation properties of a large sample of ~2300 X-ray-selected Type 2 Active Galactic Nuclei (AGNs) host galaxies out to z~3 in the Chandra COSMOS Legacy Survey in order to understand the connection between the star formation and nuclear activity. Making use of the existing multi-wavelength photometric data available in the COSMOS field, we perform a multi-component modeling from far-infrared to near-ultraviolet using a nuclear dust torus model, a stellar population model and a starburst model of the spectral energy distributions (SEDs). Through detailed analyses of SEDs, we derive the stellar masses and the star formation rates (SFRs) of Type 2 AGN host galaxies. The stellar mass of our sample is in the range of 9<logM_stellar_/M_{sun}_<12 with uncertainties of ~0.19dex. We find that Type 2 AGN host galaxies have, on average, similar SFRs compared to the normal star-forming galaxies with similar M_stellar_ and redshift ranges, suggesting no significant evidence for enhancement or quenching of star formation. This could be interpreted in a scenario, where the relative massive galaxies have already experienced substantial growth at higher redshift (z>3), and grow slowly through secular fueling processes hosting moderate-luminosity AGNs.
- ID:
- ivo://CDS.VizieR/J/MNRAS/463/24
- Title:
- Type 2 AGNs with double-peaked narrow emission lines
- Short Name:
- J/MNRAS/463/24
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- 1 per cent of redshift z~0.1 active galactic nuclei (AGNs) show velocity splitting of a few hundred km/s in the narrow emission lines in spatially integrated spectra. Such line profiles have been found to arise from the bulk motion of ionized gas clouds associated with galactic-scale outflows, merging pairs of galaxies each harbouring a supermassive black hole (SMBH), and/or galactic-scale disc rotation. It remains unclear, however, how the frequency of narrow-line velocity splitting may depend on AGN luminosity. Here we study the correlation between the fraction of Type 2 AGNs with double-peaked narrow emission lines and AGN luminosity as indicated by [OIII] {lambda}5007 emission-line luminosity L_[OIII]_. We combine the sample of Liu et al. (2010. Cat. J/ApJ/708/427) at z~0.1 with a new sample of 178 Type 2 AGNs with double-peaked [OIII] emission lines at z~0.5. We select the new sample from a parent sample of 2089 Type 2 AGNs from the SDSS-III/Baryon Oscillation Spectroscopic Survey. We find a statistically significant (~4.2{sigma}) correlation between L_[OIII}]_ and the fraction of objects that exhibit double-peaked narrow emission lines among all Type 2 AGNs, corrected for selection bias and incompleteness due to [OIII] line width, equivalent width, splitting velocity, and/or equivalent width ratio between the two velocity components. Our result suggests that galactic-scale outflows and/or merging pairs of SMBHs are more prevalent in more powerful AGNs, although spatially resolved follow-up observations are needed to resolve the origin(s) for the narrow-line velocity splitting for individual AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/708/427
- Title:
- Type 2 AGNs with double-peaked [OIII] lines
- Short Name:
- J/ApJ/708/427
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present a sample of 167 type 2 active galactic nuclei (AGNs) with double-peaked [OIII]4959,5007 narrow emission lines, selected from the Seventh Data Release of the Sloan Digital Sky Survey. The double-peaked profiles can be well modeled by two velocity components, blueshifted and redshifted from the systemic velocity. Half of these objects have a more prominent redshifted component. In cases where the H{beta} emission line is strong, it also shows two velocity components whose line-of-sight (LOS) velocity offsets are consistent with those of [OIII]. The relative LOS velocity offset between the two components is typically a few hundred km/s, larger by a factor of ~1.5 than the line full width at half maximum of each component. The offset correlates with the host stellar velocity dispersion {sigma}_*_. The host galaxies of this sample show systematically larger {sigma}_*_, stellar masses, and concentrations, and older luminosity-weighted mean stellar ages than a regular type 2 AGN sample matched in redshift, [OIII]5007 equivalent width, and luminosity; they show no significant difference in radio properties. These double-peaked features could be due to narrow-line region kinematics, or binary black holes.
- ID:
- ivo://CDS.VizieR/J/MNRAS/423/600
- Title:
- Type-1 low-z AGN emission properties
- Short Name:
- J/MNRAS/423/600
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We analyze the emission properties of a new sample of 3,579 type 1 AGN, selected from the SDSS DR7 based on the detection of broad H-{alpha} emission. The sample extends over a broad H-{alpha} luminosity L_bHa_ of 10^40^-10^44^erg/s and a broad H-{alpha} FWHM of 1,000-25,000km/s, which covers the range of black hole mass 10^6^<M_BH_/M{sun}<10^9.5^ and luminosity in Eddington units 10^-3^<L/L_Edd_<1. We combine ROSAT, GALEX and 2MASS observations to form the SED from 2.2um to 2keV. We find the following: 1. The distribution of the H-{alpha} FWHM values is independent of luminosity. 2. The observed mean optical-UV SED is well matched by a fixed shape SED of luminous quasars, which scales linearly with L_bHa_, and a host galaxy contribution. 3. The host galaxy r-band (fibre) luminosity function follows well the luminosity function of inactive non-emission line galaxies (NEG), consistent with a fixed fraction of ~3% of NEG hosting an AGN, regardless of the host luminosity. 4. The hosts of lower luminosity AGN have a mean z band luminosity and u-z colour which are identical to NEG with the same redshift distribution. With increasing L_bHa_ the AGN hosts become bluer and less luminous than NEG. The implied increasing star formation rate with L_bHa_ is consistent with the relation for SDSS type 2 AGN of similar bolometric luminosity. 5. The optical-UV SED of the more luminous AGN shows a small dispersion, consistent with dust reddening of a blue SED, as expected for thermal thin accretion disc emission. 6. There is a rather tight relation of {nu}L_{nu}_(2keV) and L_bHa_, which provides a useful probe for unobscured (true) type 2 AGN. 7. The primary parameter which drives the X-ray to UV emission ratio is the luminosity, rather than M_BH_ or L/L_Edd_.