- ID:
- ivo://CDS.VizieR/J/A+A/602/A123
- Title:
- AGN vs. host galaxy properties in COSMOS field
- Short Name:
- J/A+A/602/A123
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The coeval AGN and galaxy evolution and the observed local relations between SMBHs and galaxy properties suggest some connection or feedback between SMBH growth and galaxy build-up. We looked for correlations between properties of X-ray detected AGN and their FIR detected host galaxies, to find quantitative evidences for this connection, highly debated in the latest years. We exploit the rich multi-wavelength data set available in the COSMOS field for a large sample (692 sources) of AGN and their hosts, in the redshift range 0.1<z<4. We use X-ray data to select AGN and determine their properties (intrinsic luminosity and nuclear obscuration), and broad-band SED fitting to derive host galaxy properties (stellar mass M* and star formation rate SFR). We find that the AGN 2-10keV luminosity (LX) and the host 8-1000um star formation luminosity (LSFIR) are significantly correlated. However, the average host LSFIR has a flat distribution in bins of AGN LX, while the average AGN LX increases in bins of host LSFIR, with logarithmic slope of ~0.7, in the redshifts range 0.4<z<1.2. We also discuss the comparison between the distribution of these two quantities and the predictions from hydro-dynamical simulations. Finally we find that the average column density (NH) shows a positive correlation with the host M*, at all redshifts, but not with the SFR (or LSFIR). This translates into a negative correlation with specific SFR. Our results are in agreement with the idea that BH accretion and SF rates are correlated, but occur with different variability time scales. The presence of a positive correlation between NH and host M* suggests that the X-ray NH is not entirely due to the circum-nuclear obscuring torus, but may also include a contribution from the host galaxy.
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Search Results
- ID:
- ivo://CDS.VizieR/J/ApJ/772/26
- Title:
- AGN with WISE. II. The NDWFS Bootes field
- Short Name:
- J/ApJ/772/26
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- Stern et al. (2012ApJ...753...30S, Paper I) presented a study of Wide-field Infrared Survey Explorer (WISE) selection of active galactic nuclei (AGNs) in the 2deg^2^ COSMOS field, finding that a simple criterion W1-W2>=0.8 provides a highly reliable and complete AGN sample for W2<15.05, where the W1 and W2 passbands are centered at 3.4{mu}m and 4.6{mu}m, respectively. Here we extend this study using the larger 9deg^2^ NOAO Deep Wide-Field Survey Bootes field which also has considerably deeper WISE observations than the COSMOS field, and find that this simple color cut significantly loses reliability at fainter fluxes. We define a modified selection criterion combining the W1-W2 color and the W2 magnitude to provide highly reliable or highly complete AGN samples for fainter WISE sources. In particular, we define a color-magnitude cut that finds 130+/-4deg^-2^ AGN candidates for W2<17.11 with 90% reliability. Using the extensive UV through mid-IR broadband photometry available in this field, we study the spectral energy distributions of WISE AGN candidates. We find that, as expected, the WISE AGN selection can identify highly obscured AGNs, but that it is biased toward objects where the AGN dominates the bolometric luminosity output. We study the distribution of reddening in the AGN sample and discuss a formalism to account for sample incompleteness based on the step-wise maximum-likelihood method of Efstathiou et al. The resulting dust obscuration distributions depend strongly on AGN luminosity, consistent with the trend expected for a receding torus. At L_AGN_~3x10^44^erg/s, 29%+/-7% of AGNs are observed as Type 1, while at ~4x10^45^erg/s the fraction is 64%+/-13%. The distribution of obscuration values suggests that dust in the torus is present as both a diffuse medium and in optically thick clouds.
- ID:
- ivo://CDS.VizieR/J/ApJ/748/124
- Title:
- AGN X-ray variability in the 4Ms catalog
- Short Name:
- J/ApJ/748/124
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- The 4 Ms Chandra Deep Field-South (CDF-S) and other deep X-ray surveys have been highly effective at selecting active galactic nuclei (AGNs). However, cosmologically distant low-luminosity AGNs (LLAGNs) have remained a challenge to identify due to significant contribution from the host galaxy. We identify long-term X-ray variability (~month-years, observed frame) in 20 of 92 CDF-S galaxies spanning redshifts z{approx}0.08-1.02 that do not meet other AGN selection criteria. We show that the observed variability cannot be explained by X-ray binary populations or ultraluminous X-ray sources, so the variability is most likely caused by accretion onto a supermassive black hole (SMBH). The variable galaxies are not heavily obscured in general, with a stacked effective power-law photon index of {Gamma}_stack_{approx}1.93+/-0.13, and are therefore likely LLAGNs. The LLAGNs tend to lie a factor of {approx}6-80 below the extrapolated linear variability-luminosity relation measured for luminous AGNs.
- ID:
- ivo://CDS.VizieR/J/ApJS/216/17
- Title:
- AKARI 2.5-5um spectra of nearby Type-1 AGNs
- Short Name:
- J/ApJS/216/17
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present 2.5-5.0{mu}m spectra of 83 nearby (0.002<z<0.48) and bright (K<14mag) type-1 active galactic nuclei (AGNs) taken with the Infrared Camera on board AKARI. The 2.5-5.0{mu}m spectral region contains emission lines such as Br{beta} (2.63{mu}m), Br{alpha} (4.05{mu}m), and polycyclic aromatic hydrocarbons (3.3{mu}m), which can be used for studying the black hole (BH) masses and star formation activity in the host galaxies of AGNs. The spectral region also suffers less dust extinction than in the ultra violet (UV) or optical wavelengths, which may provide an unobscured view of dusty AGNs. Our sample is selected from bright quasar surveys of Palomar-Green and SNUQSO, and AGNs with reverberation-mapped BH masses from Peterson et al. Using 11 AGNs with reliable detection of Brackett lines, we derive the Brackett-line-based BH mass estimators. We also find that the observed Brackett line ratios can be explained with the commonly adopted physical conditions of the broad line region. Moreover, we fit the hot and warm dust components of the dust torus by adding photometric data of SDSS, 2MASS, WISE, and ISO to the AKARI spectra, finding hot and warm dust temperatures of ~1100K and ~220K, respectively, rather than the commonly cited hot dust temperature of 1500K.
- ID:
- ivo://CDS.VizieR/IX/48
- Title:
- Allsky cross-matched 3XMMe catalogue
- Short Name:
- IX/48
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- ARCHES (Astronomical Resource Cross-matching for High Energy Studies) is a FP7-Space funded project whose aim is to provide the astronomical community with well-characterised multi-wavelength data in the form of spectral energy distributions (SEDs) for large samples of objects extracted from the 3XMM DR5 X-ray catalogue of serendipitous sources. The project has developed new tools implementing fully probabilistic simultaneous cross-correlation of several catalogues for unresolved sources. A cleaned and enhanced version of the 3XMM DR5 catalogue (the 3XMMe catalogue) has been cross-correlated using the ARCHES tool with a number of selected multi-wavelength archival catalogues. These catalogues cover wavelengths ranging from UV to far IR. They provide probabilities of associations, magnitude and fluxes from which spectral energy distributions can be extracted.
- ID:
- ivo://CDS.VizieR/J/ApJS/171/61
- Title:
- All-Sky Survey of Flat-Spectrum Radio Sources
- Short Name:
- J/ApJS/171/61
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We have assembled an 8.4GHz survey of bright, flat-spectrum ({alpha}>-0.5) radio sources with nearly uniform extragalactic (|b|>10{deg}) coverage for sources brighter than S_4.8GHz_=65mJy. The catalog is assembled from existing observations (especially CLASS and the Wright et al., Cat VIII/38, PMN-CA survey), augmented by reprocessing of archival VLA and ATCA data and by new observations to fill in coverage gaps. We refer to this program as CRATES, the Combined Radio All-Sky Targeted Eight GHz Survey. The resulting catalog provides precise positions, subarcsecond structures, and spectral indices for some 11000 sources. We describe the morphology and spectral index distribution of the sample and comment on the survey's power to select several classes of interesting sources, especially high-energy blazars. Comparison of CRATES with other high-frequency surveys also provides unique opportunities for identification of high-power radio sources.
- ID:
- ivo://CDS.VizieR/J/A+A/580/A113
- Title:
- A low-luminosity type-1 QSO sample. III.
- Short Name:
- J/A+A/580/A113
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We report on the optical spectroscopic analysis of a sample of 99 low-luminosity quasi-stellar objects (LLQSOs) at z<=0.06 base the Hamburg/ESO QSO Survey (HES). To better relate the low-redshift active galactic nucleus (AGN) to the QSO population it is important to study samples of the latter type at a level of detail similar to that of the low-redshift AGN. Powerful QSOs, however, are absent at low redshifts due to evolutionary effects and their small space density. Our understanding of the (distant) QSO population is, therefore, significantly limited by angular resolution and sensitivity. The LLQSOs presented here offer the possibility of studying the faint end of this population at smaller cosmological distances and, therefore, in greater detail. In comparing two spectroscopic methods, we aim to establish a reliable activity classification scheme of the LLQSOs sample. Our goal is to enrich our systematic multiwavelength analysis of the AGN/starburst relation in these systems and give a complementary information on this particular sample of LLQSOs from the Hamburg ESO survey. Here, we present results of the analysis of visible wavelength spectroscopy provided by the HES and the 6 Degree Field Galaxy Survey (6dFGS). These surveys use different spectroscopic techniques, long-slit and circular fiber, respectively. These allow us to assess the influence of different apertures on the activity of the LLQSOs using classical optical diagnostic diagrams. We perform a Gaussian fitting of strong optical emission lines and decompose narrow and broad Balmer components. A small number of our LLQSO present no broad component, which is likely to be present but buried in the noise. Two sources show double broad components, whereas six comply with the classic NLS1 requirements. As expected in NLR of broad line AGNs, the [SII]-based electron density values range between 100 and 1000N_e_/cm^3^. Using the optical characteristics of Populations A and B, we find that 50% of our sources with H{beta} broad emission are consistent with the radio-quiet sources definition. The remaining sources could be interpreted as low-luminosity radio-loud quasar. The BPT-based classification renders an AGN/Seyfert activity between 50 to 60%. For the remaining sources, the possible starburst contribution might control the LINER and HII classification. Finally, we discuss the aperture effect as responsible for the differences found between data sets, although variability in the BLR could play a significant role as well.
- ID:
- ivo://CDS.VizieR/J/A+A/545/A15
- Title:
- AMIGA XI. Optical nuclear activity
- Short Name:
- J/A+A/545/A15
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- This study was performe within the frame of the AMIGA project (http://amiga.iaa.es/). We obtained spectral data from the 6th Data Release of the Sloan Digital Sky Survey, which were inspected in a semi-automatic way. We subtracted the underlying stellar populations from the spectra (using the software Starlight) and modelled the nuclear emission features. Standard emission-line diagnostics diagrams were applied, using a new classification scheme that takes into account censored data, to classify the type of nuclear emission. We provide a final catalogue of spectroscopic data, stellar populations, emission lines and classification of optical nuclear activity for AMIGA galaxies. The prevalence of optical active galactic nuclei (AGN) in AMIGA galaxies is 20.4%, or 36.7% including transition objects. The fraction of AGN increases steeply towards earlier morphological types and higher luminosities. We compare these results with a matched analysis of galaxies in isolated denser environments (Hickson Compact Groups). After correcting for the effects of the morphology and luminosity, we find that there is no evidence for a difference in the prevalence of AGN between isolated and compact group galaxies, and we discuss the implications of this result. We find that a major interaction is not a necessary condition for the triggering of optical AGN.
- ID:
- ivo://CDS.VizieR/J/A+A/549/A39
- Title:
- A 3mm molecular line survey of NGC1068
- Short Name:
- J/A+A/549/A39
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We study the molecular composition of the interstellar medium (ISM) surrounding an active galactic nucleus (AGN), by making an inventory of molecular species and their abundances, to establish a chemical differentiation between starburst galaxies and AGN. We used the IRAM-30m telescope to observe the central 1.5-2kpc region of NGC 1068, covering the frequencies between 86.2GHz and 115.6GHz. Using Boltzmann diagrams, we calculated the column densities of the detected molecules. We used a chemical model to reproduce the abundances found in the AGN, to determine the origin of each detected species, and to test the influence of UV fields, cosmic rays, and shocks on the ISM.
- ID:
- ivo://CDS.VizieR/J/ApJS/189/1
- Title:
- A 3.5mm polarimetric survey of radio-loud AGNs
- Short Name:
- J/ApJS/189/1
- Date:
- 21 Oct 2021
- Publisher:
- CDS
- Description:
- We present the results from the first large (>100 sources) 3.5mm polarimetric survey of radio-loud active galactic nuclei (AGNs). This wavelength is favorable within the radio-millimeter range for measuring the intrinsic linearly polarized emission from AGNs, since in general it is only marginally affected by Faraday rotation of the electric vector position angle and depolarization. The I, Q, U, and V Stokes parameter observations were performed with the XPOL polarimeter at the IRAM 30m Telescope on different observing epochs from 2005 July (when most of the measurements were made) to 2009 October. Our sample consists of 145 flat-radio-spectrum AGNs with declination >-30{deg} (J2000.0) and flux density >~1Jy at ~86GHz, as measured at the IRAM 30m Telescope from 1978 to 1994. This constraint on the radio spectrum causes our sample to be dominated by blazars, which allows us to conduct new statistical studies on this class of high-luminosity, relativistically beamed emitters. Over our entire source sample, the luminosity of the jets is anticorrelated with the degree of linear polarization. Consistent with previous findings claiming larger Doppler factors for brighter {gamma}-ray blazars, quasars listed in our sample, and in the Fermi Large Area Telescope Bright Source Catalog (LBAS, Abdo et al., 2009ApJ...700..597A), show larger luminosities than non-LBAS ones, but our data do not allow us to confirm the same for BL Lac objects. Our new data can be used to estimate the 3.5mm AGN contribution to measurements of the linear polarization of the cosmic microwave background, such as those performed by the Planck satellite.
