J/ApJ/878/11 Type 1 vs 2 X-ray-selected COSMOS AGNs & environment (Zou+, 2019)
The host-galaxy properties of type 1 versus type 2 active galactic nuclei.
Zou F., Yang G., Brandt W.N., Xue Y.
<Astrophys. J., 878, 11 (2019)>
=2019ApJ...878...11Z 2019ApJ...878...11Z
ADC_Keywords: Active gal. nuclei; Redshifts; QSOs; X-ray sources;
Infrared sources
Keywords: galaxies: active ; galaxies: nuclei ; galaxies: statistics ;
quasars: supermassive black holes
Abstract:
The unified model of active galactic nuclei (AGNs) proposes that
different AGN optical spectral types are caused by different viewing
angles with respect to an obscuring "torus". Therefore, this model
predicts that type 1 and type 2 AGNs should have similar host-galaxy
properties. We investigate this prediction with 2463 X-ray-selected
AGNs in the COSMOS field. We divide our sample into type 1 and type 2
AGNs based on their spectra, morphologies, and variability. We derive
their host-galaxy stellar masses (M*) through spectral energy
distribution (SED) fitting, and we find that the hosts M* of type 1
AGNs tend to be slightly smaller than those of type 2 AGNs by
ΔlogM*∼0.2dex (∼4σ significance). Besides deriving star
formation rates (SFRs) from SED fitting, we also utilize far-infrared
(FIR) photometry and a stacking method to obtain FIR-based SFRs. We
find that the SFRs of type 1 and type 2 sources are similar once their
redshifts and X-ray luminosities are controlled. We also investigate
the cosmic environment, and we find that the surface number densities
(sub-Mpc) and cosmic-web environments (∼1-10Mpc) are similar for both
populations. In summary, our analyses show that the host galaxies of
type 1 and type 2 AGNs have similar SFRs and cosmic environments in
general, but the former tend to have a lower M* than the latter. The
difference in M* indicates that the AGN unification model is not
strictly correct, and both host galaxy and torus may contribute to the
optical obscuration of AGNs.
Description:
Our sample is drawn from X-ray-detected sources in the COSMOS-Legacy
Survey (Civano+ 2016, J/ApJ/819/62).
The high angular resolution of Chandra (∼0.5") in the COSMOS-Legacy
Survey enables reliable cross-matching between the X-ray catalog and
IR-to-ultraviolet (UV) catalogs (Marchesi+ 2016, J/ApJ/817/34).
In total, 2463 sources are left after removing the masked sources (see
Section 2). We adopt the redshifts in Marchesi+ (2016, J/ApJ/817/34),
and 1434 sources have reliable spectroscopic redshift measurements.
Throughout this paper, we adopt a flat ΛCDM cosmology with
H0=70km/s/Mpc, ΩΛ=0.73, and ΩM=0.27.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 103 2463 Source catalog (table sent by the author)
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See also:
II/284 : COSMOS Multi-Wavelength Photometry Catalog (Capak+, 2007)
VIII/103 : Herschel Multi-tiered Extragalactic Survey (Oliver+, 2012)
VIII/95 : Herschel Multi-tiered Extragalactic Survey (Oliver+, 2012)
J/ApJ/639/37 : AGN Seyfert galaxies and close neighbors (Koulouridis+, 2006)
J/A+A/497/635 : XMM-Newton wide-field survey in COSMOS (Cappelluti+, 2009)
J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009)
J/ApJS/184/218 : The zCOSMOS 10k-bright spectroscopic sample (Lilly+, 2009)
J/ApJ/716/348 : The XMM-Newton survey of the COSMOS field (Brusa+, 2010)
J/A+A/532/A90 : PACS Evolutionary Probe (PEP-DR1) catalogs (Lutz+, 2011)
J/ApJ/742/61 : Phot. redshift of AGNs from XMM- and C-COSMOS (Salvato+ 2011)
J/MNRAS/427/3103 : COSMOS field supermassive black holes (Bongiorno+, 2012)
J/ApJS/201/30 : The Chandra COSMOS survey. III. (Civano+, 2012)
J/ApJ/759/139 : Herschel+MIPS photometry of GOODS sources (Kirkpatrick+, 2012)
J/ApJ/763/133 : Broad-line AGN with host galaxy colors (Trump+, 2013)
J/ApJS/220/12 : FMOS-COSMOS survey III. 0.7<z<2.5 galaxies (Silverman+, 2015)
J/ApJ/819/62 : The COSMOS-Legacy Survey (CLS) catalog (Civano+, 2016)
J/ApJS/224/24 : The COSMOS2015 catalog (Laigle+, 2016)
J/ApJ/817/34 : C-COSMOS Legacy sources multiwavelength cat. (Marchesi+, 2016)
J/MNRAS/464/4545 : Gamma Ray Bursts with Swift (2004-2015) (Buchner+, 2017)
J/A+A/602/A123 : AGN vs. host galaxy data in COSMOS field (Lanzuisi+, 2017)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.7 deg RAdeg [149.4/150.8] Right ascension (J2000)
from Marchesi+, 2016, J/ApJ/817/34
K-band counterpart
13- 21 F9.7 deg DEdeg [1.6/2.82] Declination (J2000)
from Marchesi+, 2016, J/ApJ/817/34
K-band counterpart
23- 27 F5.3 --- z [0.03/6.84] Redshift
29- 32 A4 --- n_z Type of z ("spec"=spectroscopic redshift
(1434 occurrences); or "phot")
34- 36 A3 --- Class AGN classification (2)
38- 43 F6.3 [10-7W] logLx [39.77/45.56] log rest frame 2-10keV
luminosity; in erg/s units
45- 51 F7.4 [Msun] logM [6.5/12.41]? log stellar mass
53- 60 F8.4 [Msun] logM_BT1 [-99/12.2] log type 1 template
stellar mass
from Buat+ 2015A&A...577A.141B 2015A&A...577A.141B (3)
62- 69 F8.5 [Msun/yr] logSFR_SED [-5.5/4.4]? log Star Formation Rate
from SED
71- 78 F8.5 [Msun/yr] logSFR_FIR [-0.6/3.6]? log Star Formation Rate
from FIR
80- 89 F10.7 [-] log(1+del) [-1.03/1.1]? Overdensity parameter
(1+δ) (4)
91- 93 F3.1 --- Web [0/2]? Cosmic-web environment (5)
95-103 A9 --- ID Source designation (1)
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Note (1): Name of the source in Civano+ 2016, J/ApJ/819/62 and
Marchesi+ 2016, J/ApJ/817/34
(<[CMC2016] lid NNNNN> or <[ECV2009] NNNNN> in Simbad).
Note (2): There are four kinds of classes as follows:
ST1 = spectroscopic type 1 (326 occurrences),
ST2 = spectroscopic type 2 (836 occurrences),
QT1 = point-like or varying quasar (QSOV) type 1 (355 occurrences), and
QT2 = point-like or varying quasar (QSOV) type 2 (946 occurrences).
See Section 3.1 for more details of the classifications.
Note (3): For the ST2 and QT2 samples these values are set to -99.0.
Note (4): We probe both host-galaxy local (sub-Mpc) and global (∼1-10Mpc)
environment based on the latest work on the cosmic environment in
COSMOS by Yang+ (2018MNRAS.480.1022Y 2018MNRAS.480.1022Y), who utilized a new technique to
construct a measurement of the density field and the cosmic web up to
z=3 for COSMOS.
To assess the local environment, they define a dimensionless
overdensity parameter for each source:
Equation (4)=1+δ=Σ/Σmedian where Σ is
surface number density, and Σmedian is the median value of
Σ within z±0.2 at redshift z.
See Section 3.4.
Note (5): As mentioned in Section 3.4, the global environment is classified as
"field," "filament," or "cluster," and only "field" and "filament" are
defined above z=1.2. Code as follows:
0.0 = cluster (76 occurrences);
1.0 = filament (1120 occurrences);
2.0 = field (800 occurrences).
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Acknowledgments:
Fan Zou [zf951020 at mail.ustc.edu.cn]
History:
Table in FITS format sent by the author with the additional ID column.
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 26-Nov-2020