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- ID:
- ivo://CDS.VizieR/J/ApJ/697/506
- Title:
- Mid-infrared galaxy luminosity function from AGN
- Short Name:
- J/ApJ/697/506
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present galaxy luminosity functions at 3.6, 4.5, 5.8, and 8.0um measured by combining photometry from the IRAC Shallow Survey with redshifts from the AGN and Galaxy Evolution Survey (AGES) of the NOAO Deep Wide-Field Survey Bootes field. The well defined IRAC samples contain 3800-5800 galaxies for the 3.6-8.0um bands with spectroscopic redshifts and z<0.6. We obtained relatively complete luminosity functions in the local redshift bin of z<0.2 for all four IRAC channels that are well fitted by Schechter functions.
- ID:
- ivo://CDS.VizieR/J/MNRAS/454/766
- Title:
- Mid-infrared-X-ray correlation for local AGNs
- Short Name:
- J/MNRAS/454/766
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present an updated mid-infrared (MIR) versus X-ray correlation for the local active galactic nuclei (AGN) population based on the high angular resolution 12 and 18{mu}m continuum fluxes from the AGN subarcsecond MIR atlas and 2-10 keV and 14-195 keV data collected from the literature. We isolate a sample of 152 objects with reliable AGN nature and multi-epoch X-ray data and minimal MIR contribution from star formation. Although the sample is not homogeneous or complete, we show that our results are unlikely to be affected by significant biases. The MIR-X-ray correlation is nearly linear and within a factor of 2 independent of the AGN type and the wavebands used. The observed scatter is <0.4 dex. A possible flattening of the correlation slope at the highest luminosities probed (~10^45^ erg/s) towards low MIR luminosities for a given X-ray luminosity is indicated but not significant. Unobscured objects have, on average, an MIR-X-ray ratio that is only <=0.15 dex higher than that of obscured objects. Objects with intermediate X-ray column densities (22<logN_H_<23) actually show the highest MIR-X-ray ratio on average. Radio-loud objects show a higher mean MIR-X-ray ratio at low luminosities while the ratio is lower than average at high luminosities. This may be explained by synchrotron emission from the jet contributing to the MIR at low luminosities and additional X-ray emission at high luminosities. True Seyfert 2 candidates do not show any deviation from the general behaviour suggesting that they possess a dusty obscurer as in other AGN. Double AGN also do not deviate. Finally, we show that the MIR-X-ray correlation can be used to investigate the AGN nature of uncertain objects. Specifically, we give equations that allow us to determine the intrinsic 2-10 keV luminosities and column densities for objects with complex X-ray properties to within 0.34 dex. These techniques are applied to the uncertain objects of the remaining AGN MIR atlas, demonstrating the usefulness of the MIR-X-ray correlation as an empirical tool.
- ID:
- ivo://CDS.VizieR/J/ApJ/680/130
- Title:
- Mid-IR colors of AGNs in the MUSYC ECDF-S
- Short Name:
- J/ApJ/680/130
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the mid-infrared colors of X-ray-detected AGNs and explore mid-infrared selection criteria. Using a statistical matching technique, the likelihood ratio, over 900 IRAC counterparts were identified with a new MUSYC X-ray source catalog that includes ~1000 published X-ray sources in the Chandra Deep Field-South and Extended Chandra Deep Field-South. Most X-ray-selected AGNs have IRAC spectral shapes consistent with power-law slopes, f_{nu}_{prop.to}{nu}^{alpha}^, and display a wide range of colors, -2<=alpha}<=2 Although X-ray sources typically fit to redder (more negative {alpha}) power laws than non-X-ray-detected galaxies, more than 50% do have flat or blue (galaxy-like) spectral shapes in the observed 3-8um band. Only a quarter of the X-ray-selected AGNs detected at 24um are well fit by featureless red power laws in the observed 3.6-24um, likely the subset of our sample whose infrared spectra are dominated by emission from the central AGN region. Most IRAC color selection criteria fail to identify the majority of X-ray-selected AGNs, finding only the more luminous AGNs, the majority of which have broad emission lines. In deep surveys, these color selection criteria select 10%-20% of the entire galaxy population and miss many moderate-luminosity AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJ/725/2270
- Title:
- Mid-IR emission lines in AGNs
- Short Name:
- J/ApJ/725/2270
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We used Spitzer/Infrared Spectrograph spectroscopic data on 426 galaxies including quasars, Seyferts, LINERs, and HII galaxies to investigate the relationship among the mid-IR emission lines. There is a tight linear correlation between the [NeV]14.3um and 24.3um (97.1eV) and the [OIV]25.9um (54.9eV) high-ionization emission lines. The correlation also holds for these high-ionization emission lines and the [NeIII]15.56um (41eV) emission line, although only for active galaxies. We used these correlations to calculate the [NeIII] excess due to star formation in Seyfert galaxies. We also estimated the [OIV] luminosity due to star formation in active galaxies and determined that it dominates the [OIV] emission only if the contribution of the active nucleus to the total luminosity is below 5%. We find that the active galactic nucleus dominates the [OIV] emission in most Seyfert galaxies, whereas star formation adequately explains the observed [OIV] emission in optically classified HII galaxies. Finally, we computed photoionization models to determine the physical conditions of the narrow-line region where these high-ionization lines originate. The estimated ionization parameter range is -2.8<logU<-2.5 and the total hydrogen column density range is 20<logn_H_(cm^-2^)<21.
- ID:
- ivo://CDS.VizieR/J/A+A/570/A110
- Title:
- Mid-IR properties of OH maser galaxies
- Short Name:
- J/A+A/570/A110
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We compiled all 119 OH maser galaxies (110 out of them are megamasers, i.e., L_OH_>10L_{sun}_) published so far and cross-identified these OH masers with the Wide-Field Infrared Survey Explorer (WISE) catalog, to investigate the middle infrared (MIR) properties of OH maser galaxies. The WISE magnitude data at the 3.4, 4.6, 12 and 22{mu}m (W1 to W4) are collected for the OH maser sample and one control sample, which are non-detection sources. The color-color diagrams show that both OH megamaser (OHM) and non-OHM (ultra)luminous infrared galaxies ((U)LIRGs) are far away from the single blackbody model line and many of them can follow the path described by the power-law model. The active galaxy nuclei (AGN) fraction is about ~40% for both OHM and non-OHM (U)LIRGs, according to the AGN criteria W1-W2>=0.8. Among the Arecibo survey sample, OHM sources tend to have a lower luminosity at short MIR wavelengths (e.g., 3.4{mu}m and 4.6{mu}m) than that of non-OHM sources, which should come from the low OHM fraction among the survey sample with large 3.4{mu}m and 4.6{mu}m luminosity. The OHM fraction tends to increase with cooler MIR colors (larger F_22{mu}m_/F_3.4{mu}m_). These may be good for sample selection when searching OH megamasers, such as excluding extreme luminous sources at short MIR wavelengths, choosing sources with cooler MIR colors. In the case of the power-law model, we derived the spectral indices for our samples. For the Arecibo survey sample, OHM (U)LIRGs tend to have larger spectral index {alpha}_22-12_ than non-OHM sources, which agrees with previous results. One significant correlation exists between the WISE infrared luminosity at 22{mu}m and the color [W1]-[W4] for the Arecibo OHM hosts. These clues should provide suitable constraints on the sample selection for OH megamaser surveys by future advanced telescopes (e.g., FAST). In addition, the correlation of maser luminosity and the MIR luminosity of maser hosts tends to be non-significant, which may indirectly support the pumping of OHM emission that is dominated by the far infrared radiation, instead of the MIR radiation.
- ID:
- ivo://CDS.VizieR/J/ApJ/716/530
- Title:
- Mid-IR variability from the SDWFS
- Short Name:
- J/ApJ/716/530
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We use the multi-epoch, mid-infrared Spitzer Deep Wide-Field Survey (SDWFS; Ashby et al. 2009, Cat. J/ApJ/701/428) to investigate the variability of objects in 8.1deg^2^ of the NOAO Deep Wide Field Survey Bootes field (NDWFS; Jannuzi & Dey 1999ASPC..191..111J). We perform a Difference Image Analysis of the four available epochs between 2004 and 2008, focusing on the deeper 3.6 and 4.5um bands. Out of 474, 179 analyzed sources, 1.1% meet our standard variability selection criteria that the two light curves are strongly correlated (r>0.8) and that their joint variance ({sigma}_12_) exceeds that for all sources with the same magnitude by 2{sigma}. We then examine the mid-IR colors of the variable sources and match them with X-ray sources from the XBootes survey (Murray et al. 2005ApJS..161....1M), radio catalogs (FIRST (Becker et al., Cat. VIII/71) and WSRT (de Vries et al. 2002, Cat. J/AJ/123/1784)), 24um selected active galactic nucleus (AGN) candidates (see Houck et al. 2005ApJ...622L.105H), and spectroscopically identified AGNs from the AGN and Galaxy Evolution Survey (AGES; C. S. Kochanek et al. 2010, in prep). Based on their mid-IR colors, most of the variable sources are AGNs (76%), with smaller contributions from stars (11%), galaxies (6%), and unclassified objects, although most of the stellar, galaxy, and unclassified sources are false positives. For our standard selection criteria, 11%-12% of the mid-IR counterparts to X-ray sources, 24um AGN candidates, and spectroscopically identified AGNs show variability.
- ID:
- ivo://CDS.VizieR/J/A+AS/102/611
- Title:
- Millimeter continuum of extragal. sources III.
- Short Name:
- J/A+AS/102/611
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- (no description available)
- ID:
- ivo://CDS.VizieR/J/ApJ/719/763
- Title:
- Millimeter-wave sources in the SPT survey
- Short Name:
- J/ApJ/719/763
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report the results of an 87deg^2^ point-source survey centered at R.A. 5h30m, decl. -55{deg} taken with the South Pole Telescope at 1.4 and 2.0mm wavelengths with arcminute resolution and milli-Jansky depth. Based on the ratio of flux in the two bands, we separate the detected sources into two populations, one consistent with synchrotron emission from active galactic nuclei and the other consistent with thermal emission from dust. We present source counts for each population from 11 to 640mJy at 1.4mm and from 4.4 to 800mJy at 2.0mm. The 2.0mm counts are dominated by synchrotron-dominated sources across our reported flux range; the 1.4mm counts are dominated by synchrotron-dominated sources above ~15mJy and by dust-dominated sources below that flux level. We detect 141 synchrotron-dominated sources and 47 dust-dominated sources at signal-to-noise ratio S/N>4.5 in at least one band. All of the most significantly detected members of the synchrotron-dominated population are associated with sources in previously published radio catalogs. Some of the dust-dominated sources are associated with nearby (z<<1) galaxies whose dust emission is also detected by the Infrared Astronomy Satellite. However, most of the bright, dust-dominated sources have no counterparts in any existing catalogs. We argue that these sources represent the rarest and brightest members of the population commonly referred to as submillimeter galaxies (SMGs).
- ID:
- ivo://CDS.VizieR/J/ApJS/252/32
- Title:
- MIR outbursts in nearby SDSS gal. (MIRONG). I.
- Short Name:
- J/ApJS/252/32
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Optical time-domain astronomy has grown rapidly in the past decade, but the dynamic infrared sky is rarely explored. Aiming to construct a sample of mid-infrared outbursts in nearby galaxies (MIRONG), we have conducted a systematical search of low-redshift (z<0.35) Sloan Digital Sky Survey spectroscopic galaxies that have experienced recent mid-infrared (MIR) flares using their Wide-field Infrared Survey Explorer (WISE) light curves. A total of 137 galaxies have been selected by requiring a brightening amplitude of 0.5mag in at least one WISE band with respect to their quiescent phases. Only a small fraction (10.9%) has corresponding optical flares. Except for the four supernovae (SNe) in our sample, the MIR luminosities of the remaining sources (L_4.6{mu}m_>10^42^erg/s) are markedly brighter than known SNe, and their physical locations are very close to the galactic center (median <0.1"). Only four galaxies are radio-loud, indicating that synchrotron radiation from relativistic jets could contribute to MIR variability. We propose that these MIR outbursts are dominated by the dust echoes of transient accretion onto supermassive black holes, such as tidal disruption events (TDEs) and turn-on (changing-look) active galactic nuclei. Moreover, the inferred peak MIR luminosity function is generally consistent with the X-ray and optical TDEs at the high end, albeit with large uncertainties. Our results suggest that a large population of transients has been overlooked by optical surveys, probably due to dust obscuration or intrinsically optical weakness. Thus, a search in the infrared band is crucial for us to obtain a panoramic picture of nuclear outburst. The multiwavelength follow-up observations of the MIRONG sample are in progress and will be presented in a series of subsequent papers.
