- ID:
- ivo://CDS.VizieR/J/ApJ/841/76
- Title:
- Intrinsic far-IR SED of luminous AGNs
- Short Name:
- J/ApJ/841/76
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The range of currently proposed active galactic nucleus (AGN) far-infrared templates results in uncertainties in retrieving host galaxy information from infrared observations and also undermines constraints on the outer part of the AGN torus. We discuss how to test and reconcile these templates. Physically, the fraction of the intrinsic AGN IR-processed luminosity compared with that from the central engine should be consistent with the dust-covering factor. In addition, besides reproducing the composite spectral energy distributions (SEDs) of quasars, a correct AGN IR template combined with an accurate library of star-forming galaxy templates should be able to reproduce the IR properties of the host galaxies, such as the luminosity-dependent SED shapes and aromatic feature strengths. We develop tests based on these expected behaviors and find that the shape of the AGN intrinsic far-IR emission drops off rapidly starting at ~20{mu}m and can be matched by an Elvis+ (1994, J/ApJS/95/1)-like template with a minor modification. Despite the variations in the near- to mid-IR bands, AGNs in quasars and Seyfert galaxies have remarkably similar intrinsic far-IR SEDs at {lambda}~20-100{mu}m, suggesting a similar emission character of the outermost region of the circumnuclear torus. The variations of the intrinsic AGN IR SEDs among the type-1 quasar population can be explained by the changing relative strengths of four major dust components with similar characteristic temperatures, and there is evidence for compact AGN-heated dusty structures at sub-kiloparsec scales in the far-IR.
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Search Results
- ID:
- ivo://CDS.VizieR/J/A+A/376/28
- Title:
- Inversion of the HE 1122-1648 UVES spectrum
- Short Name:
- J/A+A/376/28
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- File tablea1.dat contains the list of the Lyman-{alpha} absorption lines identified in the spectrum of HE 1122-1648 obtained during Science Verification of UVES at the VLT. We used the standard method of Voigt Profile fitting with VPFIT and with the inversion method described in the related paper. (Note that the printed version of the paper indicates HE 1122-1628, instead of the quasar HE 1122-1648).
- ID:
- ivo://CDS.VizieR/J/ApJS/168/213
- Title:
- Ionization states and cooling efficiencies
- Short Name:
- J/ApJS/168/213
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present new computations of the equilibrium and nonequilibrium cooling efficiencies and ionization states for low-density radiatively cooling gas containing the elements H, He, C, N, O, Ne, Mg, Si, S, and Fe. We present results for gas temperatures between 10^4^ and 10^8^K, assuming dust-free and optically thin conditions, and no external radiation.
- ID:
- ivo://CDS.VizieR/J/AJ/159/216
- Title:
- Ions density in the CGM of low mass galaxy groups
- Short Name:
- J/AJ/159/216
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We explore how environment affects the metallicity of the circumgalactic medium (CGM) using 13 low-mass galaxy groups (two to five galaxies) at <z_abs_>=0.25 identified near background quasars. Using quasar spectra from the Hubble Space Telescope/Cosmic Origins Spectrograph (HST/COS) and from Keck/High Resolution Echelle Spectrometer (Keck/HIRES) or the Very Large Telescope/Ultraviolet and Visual Echelle Spectrograph (VLT/UVES), we measure column densities of or determine limits on CGM absorption lines. We use a Markov Chain Monte Carlo approach with Cloudy to estimate metallicities of cool (T~104K) CGM gas within groups and compare them to CGM metallicities of 47 isolated galaxies. Both group and isolated CGM metallicities span a wide range (-2<[Si/H]<0), where the mean group (-0.54{pm}0.22) and isolated (-0.77{pm}0.14) CGM metallicities are similar. Group and isolated environments have similar distributions of HI column densities as a function of impact parameter. However, contrary to isolated galaxies, we do not find an anticorrelation between HI column density and the nearest group galaxy impact parameter. We additionally divided the groups by member luminosity ratios (i.e., galaxy-galaxy and galaxy-dwarf groups). While there was no significant difference in their mean metallicities, a modest increase in sample size should allow one to statistically identify a higher CGM metallicity in galaxy-dwarf groups compared to galaxy-galaxy groups. We conclude that either environmental effects have not played an important role in the metallicity of the CGM at this stage and expect that this may only occur when galaxies are strongly interacting or merging or that some isolated galaxies have higher CGM metallicities due to past interactions. Thus, environment does not seem to be the cause of the CGM metallicity bimodality.
- ID:
- ivo://CDS.VizieR/J/ApJ/761/184
- Title:
- IR luminosities for dusty AGNs and QSOs
- Short Name:
- J/ApJ/761/184
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Mid-infrared spectroscopic measurements from the Infrared Spectrometer (IRS) on Spitzer are given for 125 hard X-ray active galactic nuclei (AGNs; 14-195keV) from the Swift Burst Alert Telescope (BAT) sample and for 32 AGNs with black hole masses (BHMs) from reverberation mapping. The 9.7{mu}m silicate feature in emission or absorption defines an infrared AGN classification describing whether AGNs are observed through dust clouds, indicating that 55% of the BAT AGNs are observed through dust. The 100 most luminous type 1 quasars as measured in {nu}L_{nu}_(7.8{mu}m) are found by comparing Sloan Digital Sky Survey (SDSS) optically discovered quasars with photometry at 22{mu}m from the Wide-Field Infrared Survey Explorer (WISE), scaled to rest frame 7.8{mu}m using an empirical template determined from IRS spectra. The most luminous SDSS/WISE quasars have the same maximum infrared luminosities for all 1.5<z<5, reaching total infrared luminosity L_IR_=10^14.4^L_{sun}_. Comparing with dust-obscured galaxies from Spitzer and WISE surveys, we find no evidence of hyperluminous obscured quasars whose maximum infrared luminosities exceed the maximum infrared luminosities of optically discovered quasars. Bolometric luminosities L_bol_ estimated from rest-frame optical or ultraviolet luminosities are compared to L_IR_. For the local AGN, the median logL_IR_/L_bol_=-0.35, consistent with a covering factor of 45% for the absorbing dust clouds. For the SDSS/WISE quasars, the median logL_IR_/L_bol_=0.1, with extremes indicating that ultraviolet-derived L_bol_ can be seriously underestimated even for type 1 quasars.
- ID:
- ivo://CDS.VizieR/J/ApJ/679/140
- Title:
- IR measurement of quasar obscuration
- Short Name:
- J/ApJ/679/140
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Recent work has suggested that the fraction of obscured AGNs declines with increasing luminosity, but it has been difficult to quantify this trend. Here we attempt to measure this fraction as a function of luminosity by studying the ratio of mid-infrared to intrinsic nuclear bolometric luminosity in unobscured AGNs. Because the mid-infrared is created by dust reprocessing of shorter wavelength nuclear light, this ratio is a diagnostic of f_obsc_, the fraction of solid angle around the nucleus covered by obscuring matter. In order to eliminate possible redshift dependences while also achieving a large dynamic range in luminosity, we have collected archival 24um MIPS photometry from objects with z~1 in the Sloan Digital Sky Survey DR5, the Great Observatories Origins Deep Survey, and the Cosmic Evolution Survey. To measure the bolometric luminosity for each object, we used archival optical data supplemented by GALEX data.
- ID:
- ivo://CDS.VizieR/J/MNRAS/393/1408
- Title:
- IR photometry of type II quasars
- Short Name:
- J/MNRAS/393/1408
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- For this paper, we collected almost all of the type II quasars so far discovered. Among them, 485 sources have photometric data at JHK bands, mainly from Two-Micron All-Sky Survey observations, 65 sources have IRAS photometric data in at least one of the three IRAS bands at 25, 60 and 100um and 15 sources have IRAS photometric data in all three IRAS bands. We find that in nearly half of all type II quasars, both the near- and far-infrared radiations are dominated by starlight or thermal reprocessing of starlight by dust in the underlying galaxy. The infrared radiation of the other group (slightly over half) is dominated by a non-thermal radiation in the near-infrared, and mostly in the far-infrared also (although there is a mixture particularly for the longer wavelengths). It is proposed that for the later group, hidden broad lines may exist in the infrared. On the basis of our and previous results, we also discuss the possibility that there are two distinct classes of type II quasars: 'true' type II quasars without a broad-line region and heavily obscured type I quasars, in full analogy with the case for type II Seyfert galaxies. No relationships can be found for either the near-infrared or the far-infrared colours and the redshift. Correlations between absolute magnitude in the near- and far-infrared with redshift are found, but could be due to a flux limit (Malmquist bias).
- ID:
- ivo://CDS.VizieR/J/ApJ/642/673
- Title:
- IR-selected obscured AGN candidates
- Short Name:
- J/ApJ/642/673
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Using the large multiwavelength data set in the Chandra/SWIRE Survey (0.6deg^2^ in the Lockman Hole), we show evidence for the existence of highly obscured (Compton-thick) AGNs, estimate a lower limit to their surface density, and characterize their multiwavelength properties. Two independent selection methods based on the X-ray and infrared spectral properties are presented. The two selected samples contain (1) five X-ray sources with hard X-ray spectra and column densities >~10^24^cm^-2^ and (2) 120 infrared sources with red and AGN-dominated infrared SEDs. We estimate a surface density of at least 25 Compton-thick AGNs deg^2^ detected in the infrared in the Chandra/SWIRE field, of which 40% show distinct AGN signatures in their optical/near-infrared SEDs, the remaining being dominated by the host galaxy emission. Only ~33% of all Compton-thick AGNs are detected in the X-rays at our depth [F(0.3-8keV)>10^-15^ergs/cm^2^/s]. We report the discovery of two sources in our sample of Compton-thick AGNs, SWIRE J104409.95+585224.8 (z=2.54) and SWIRE J104406.30+583954.1 (z=2.43), which are the most luminous Compton-thick AGNs at high z currently known. The properties of these two sources are discussed in detail with an analysis of their spectra, SEDs, luminosities, and black hole masses.
- ID:
- ivo://CDS.VizieR/J/ApJS/214/23
- Title:
- IR spectra and photometry of z<0.5 quasars
- Short Name:
- J/ApJS/214/23
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- As a step toward a comprehensive overview of the infrared (IR) diagnostics of the central engines and host galaxies of quasars at low redshift, we present Spitzer Space Telescope spectroscopic (5-40{mu}m) and photometric (24, 70, and 160{mu}m) measurements of all Palomar-Green (PG) quasars at z<0.5 and Two Micron All Sky Survey (2MASS) quasars at z<0.3. We supplement these data with Herschel measurements at 160{mu}m. The sample is composed of 87 optically selected PG quasars and 52 near-IR-selected 2MASS quasars. Here we present the data, measure the prominent spectral features, and separate emission due to star formation from that emitted by the dusty circumnuclear torus. We find that the mid-IR (5-30{mu}m) spectral shape for the torus is largely independent of quasar IR luminosity with scatter in the spectral energy distribution (SED) shape of <~0.2dex. Except for the silicate features, no large difference is observed between PG (unobscured --silicate emission) and 2MASS (obscured --silicate absorption) quasars. Only mild silicate features are observed in both cases. When in emission, the peak wavelength of the silicate feature tends to be longer than 9.7{mu}m, possibly indicating effects on grain properties near the active galactic nucleus. The IR color is shown to correlate with the equivalent width of the aromatic features, indicating that the slope of the quasar mid- to far-IR SED is to first order driven by the fraction of radiation from star formation in the IR bands.
- ID:
- ivo://CDS.VizieR/J/ApJ/732/116
- Title:
- IR spectra of {gamma}-ray bright blazars
- Short Name:
- J/ApJ/732/116
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- A possible source of {gamma}-ray photons observed from the jets of blazars is inverse Compton scattering by relativistic electrons of infrared seed photons from a hot, dusty torus in the nucleus. We use observations from the Spitzer Space Telescope to search for signatures of such dust in the infrared spectra of four {gamma}-ray bright blazars, the quasars 4C 21.35, CTA102, and PKS 1510-089, and the BL Lacertae object ON231. The spectral energy distribution (SED) of 4C 21.35 contains a prominent infrared excess indicative of dust emission. After subtracting a non-thermal component with a power-law spectrum, we fit a dust model to the residual SED. The model consists of a blackbody with temperature ~1200K, plus a much weaker optically thin component at ~660K. The total luminosity of the thermal dust emission is 7.9+/-0.2x10^45^erg/s. If the dust lies in an equatorial torus, the density of infrared photons from the torus is sufficient to explain the {gamma}-ray flux from 4C 21.35 as long as the scattering occurs within a few parsecs of the central engine. We also report a tentative detection of dust in the quasar CTA102, in which the luminosity of the infrared excess is 7+/-2x10^45^erg/s. However, in CTA102 the far-infrared spectra are too noisy to detect the 10um silicate feature. Upper limits to the luminosity from thermal emission from dust in PKS 1510-089, and ON231, are 2.3x10^45^, and 6.6x10^43^erg/s, respectively. These upper limits do not rule out the possibility of inverse Compton upscattering of infrared photons to {gamma}-ray energies in these two sources.
