J/ApJ/876/50 X-ray & MIR AGNs in Stripe 82 with eBOSS spectra (LaMassa+, 2019)
SDSS-IV eBOSS spectroscopy of X-ray and WISE AGNs in Stripe 82X: overview of the
demographics of X-ray and mid-infrared-selected active galactic nuclei.
LaMassa S.M., Georgakakis A., Vivek M., Salvato M., Ananna T.T., Urry C.M.,
MacLeod C., Ross N.
<Astrophys. J., 876, 50 (2019)>
=2019ApJ...876...50L 2019ApJ...876...50L
ADC_Keywords: Active gal. nuclei; Surveys; Spectra, optical; Redshifts;
Photometry, SDSS; Photometry, infrared; X-ray sources
Keywords: catalogs ; galaxies: active ; surveys
Abstract:
We report the results of a Sloan Digital Sky Survey IV eBOSS program
to target X-ray sources and mid-infrared-selected Wide-field Infrared
Survey Explorer (WISE) active galactic nucleus (AGN) candidates in a
36.8deg2 region of Stripe 82. About half this survey (15.6deg2)
covers the largest contiguous portion of the Stripe 82 X-ray survey.
This program represents the largest spectroscopic survey of AGN
candidates selected solely by their WISE colors. We combine this
sample with X-ray and WISE AGNs in the field identified via other
sources of spectroscopy, producing a catalog of 4847 sources that is
82% complete to r∼22. Based on X-ray luminosities or WISE colors, 4730
of these sources are AGNs, with a median sample redshift of z∼1. About
30% of the AGNs are optically obscured (i.e., lack broad lines in
their optical spectra). BPT analysis, however, indicates that 50% of
the WISE AGNs at z<0.5 have emission line ratios consistent with
star-forming galaxies, so whether they are buried AGNs or star-forming
galaxy contaminants is currently unclear. We find that 61% of X-ray
AGNs are not selected as mid-infrared AGNs, with 22% of X-ray AGNs
undetected by WISE. Most of these latter AGNs have high X-ray
luminosities (Lx>1044erg/s), indicating that mid-infrared selection
misses a sizable fraction of the highest luminosity AGNs, as well as
lower luminosity sources where AGN-heated dust is not dominating the
mid-infrared emission. Conversely, ∼58% of WISE AGNs are undetected by
X-rays, though we do not find that they are preferentially redder than
the X-ray-detected WISE AGNs.
Description:
We reported on the results of an SDSS-IV eBOSS spectroscopic survey
that covered 36.8deg2 of Stripe 82 in the fall of 2015. About half
of this survey area (15.6deg2) overlaps the largest contiguous
region of the Stripe 82 X-ray survey observed by XMM-Newton in AO13
(PI: Urry; LaMassa+ 2016, J/ApJ/817/172). The primary targets of this
survey were X-ray sources and WISE AGN candidates from the ALLWISE
survey (Mainzer+ 2011ApJ...731...53M 2011ApJ...731...53M) identified on the basis of their
W1-W2 colors (i.e., the 75% reliability threshold of
Assef+ 2013, J/ApJ/772/26). SDSS counterparts to the X-ray and WISE
sources were identified using the statistical maximum likelihood
approach, as described in LaMassa+ (2016, , J/ApJ/817/172) for the
X-ray sources and in the main text for the WISE population. Additional
"filler" targets were observed to make use of all available
spectroscopic fibers across the SDSS plates. Subsequent to the SDSS-IV
eBOSS observing program, an updated multiwavelength catalog matched to
the Stripe 82X survey was published by Ananna+ (2017, J/ApJ/850/66),
and the W1-W2 color criteria for AGNs were modified with respect to
the eBOSS target list we created (Assef+ 2018, J/ApJS/234/23), leading
us to curate the sources in our final published catalog with respect
to the objects we targeted.
In total, 2262 SDSS counterparts to the original X-ray and WISE AGN
candidate target lists were spectroscopically observed. We visually
inspected all spectra.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
catalog.dat 457 4847 Stripe 82X eBOSS Value-added Catalog
--------------------------------------------------------------------------------
Description of file:
s82xebosscatalog_submitted.fits is the original catalog in FITS format.
See also:
II/261 : GOODS initial results (Giavalisco+, 2004)
II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/359 : The VISTA Hemisphere Survey (VHS) catalog DR4.1 (McMahon+, 2013)
VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)
VIII/92 : The FIRST Survey Catalog, Version 2014Dec17 (Helfand+ 2015)
VII/286 : SDSS quasar catalog, fourteenth data release (Paris+, 2018)
J/ApJS/121/473 : A diagnostic diagram for Seyfert 2 Galaxies (Bassani+, 1999)
J/AJ/126/539 : The Chandra Deep Fields North and South (Alexander+, 2003)
J/ApJ/642/126 : MIR observations in the extended Groth strip (Barmby+, 2006)
J/ApJS/172/29 : XMM-Newton survey in COSMOS field. I. (Hasinger+, 2007)
J/A+A/497/635 : XMM-Newton wide-field survey in COSMOS (Cappelluti+, 2009)
J/MNRAS/392/19 : The 2dF-SDSS QSO survey (Croom+, 2009)
J/ApJS/184/158 : Chandra COSMOS survey I. (Elvis+, 2009)
J/ApJ/716/348 : The XMM-Newton survey of the COSMOS field (Brusa+, 2010)
J/ApJ/708/584 : SEXSI Spitzer catalog (Eckart+, 2010)
J/ApJS/195/10 : The CDF-S survey: 4Ms source catalogs (Xue+, 2011)
J/ApJS/201/30 : The Chandra COSMOS survey. III. (Civano+, 2012)
J/ApJS/199/3 : The quasars MMT-BOSS pilot survey (Ross+, 2012)
J/ApJ/772/26 : AGN with WISE. II. The NDWFS Bootes field (Assef+, 2013)
J/MNRAS/436/3581 : X-ray observations of Stripe 82 (LaMassa+, 2013)
J/ApJ/794/120 : Sloan Digital Sky Survey coadd. Stripe 82 (Annis+, 2014)
J/ApJ/788/48 : X-ray through NIR photometry of NGC 2617 (Shappee+, 2014)
J/ApJS/210/22 : Herschel Stripe 82 survey (HerS) first cat. (Viero+, 2014)
J/ApJS/219/39 : QSOs selection from SDSS and WISE (Richards+, 2015)
J/ApJ/819/62 : The COSMOS-Legacy Survey (CLS) catalog (Civano+, 2016)
J/MNRAS/456/1359 : IAC Stripe 82 Legacy Project: Photometry (Fliri+, 2016)
J/ApJ/817/172 : X-ray Observations of Stripe 82 (LaMassa+, 2016)
J/MNRAS/459/1602 : AGN sample in the northern XMM-XXL field (Liu+, 2016)
J/MNRAS/457/110 : Northern XMM-XXL field AGN catalog (Menzel+, 2016)
J/ApJS/225/1 : SpIES: the Spitzer IRAC Equatorial Survey (Timlin+, 2016)
J/ApJ/850/66 : Stripe 82X survey multiwavelength catalog (Ananna+, 2017)
J/MNRAS/465/1831 : SDSS-IV eBOSS ELG UgrizW photometry (Delubac+, 2017)
J/ApJS/228/2 : Chandra Deep Field-South survey: 7Ms sources (Luo+, 2017)
J/ApJS/234/23 : The WISE AGN candidates catalogs (Assef+, 2018)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 F9.6 deg RAdeg [14.03/28.09] Right ascension in decimal
degrees (J2000) (SDSS_RA)
11- 19 F9.6 deg DEdeg [-1.27/1.27] Declination in decimal
degrees (J2000) (SDSS_Dec)
21- 24 I4 --- Plate [394/8793]?=-999 SDSS plate (Plate)
26- 30 I5 d MJD [51783/57391]?=-999 Modified Julian Date
of SDSS spectroscopic observation (MJD)
32- 35 I4 --- Fiber [1/1000]?=-999 SDSS fiber (Fiber)
37- 47 F11.8 --- z [-0.00082/4.2] Spectroscopic redshift
(redshift) (1)
49- 55 A7 --- OT Optical spectroscopic classification,
vetted via visual inspection (class) (2)
57- 85 A29 --- r_z Reference on redshift (z_src) (3)
87- 90 I4 --- q_z [-999/3] Confidence on spectroscopic
redshift via visual inspection (z_conf) (4)
92-101 F10.5 mag umag [15.38/29.87]?=- u-band (AB) magnitude
(u_mag) (5)
103-114 F12.7 mag e_umag [0.0004/218]?=- Error on the u-band
magnitude (u_err)
116-125 F10.5 mag gmag [12.61/25.56]?=- g-band (AB) magnitude
(g_mag) (5)
127-138 F12.7 mag e_gmag [0.0001/1]?=- Error on the g-band
magnitude (g_err)
140-149 F10.5 mag rmag [12.27/24.41]?=- r-band (AB) magnitude
(r_mag) (5)
151-162 F12.7 mag e_rmag [0.0001/2.2]?=- Error on the r-band
magnitude (r_err)
164-173 F10.5 mag imag [11.87/23.73]?=- i-band (AB) magnitude
(i_mag) (5)
175-186 F12.7 mag e_imag [0.0001/4.6]?=- Error on the i-band
magnitude (i_err)
188-197 F10.5 mag zmag [11.88/23.8]?=- z-band (AB) magnitude
(z_mag) (5)
199-210 F12.7 mag e_zmag [0.0001/0.7]?=- Error on the z-band
magnitude (z_err)
212-215 A4 --- Ref Source of optical photometry (opt_src) (6)
217-224 F8.3 mag W1mag [10/18.71]?=- WISE W1 (3.4um) band
magnitude (W1) (7)
226-233 F8.3 mag e_W1mag [0.02/0.5]?=- Error on the WISE W1 (3.4um)
band magnitude (W1sig)
235-242 F8.3 mag W2mag [9.79/17.26]?=- WISE W2 (4.6um) band
magnitude (W2) (7)
244-251 F8.3 mag e_W2mag [0.01/0.6]?=- Error on the WISE W2 (4.6um)
band magnitude (W2sig)
253-260 F8.3 mag W3mag [6.6/12.9]?=- WISE W3 (12um) band
magnitude (W3) (7)
262-269 F8.3 mag e_W3mag [0.01/0.6]?=- Error on the WISE W3 (12um)
band magnitude (W3sig)
271-278 F8.3 mag W4mag [3.6/9.4]?=- WISE W4 (22um) band magnitude
(W4) (7)
280-287 F8.3 mag e_W4mag [0.02/0.6]?=- Error on the WISE W4 (22um)
band magnitude (W4sig)
289-296 F8.3 mag R-W1 [-2.6/7.7]?=- R-W1 (Vega) color index (R-W1)
298-305 F8.3 mag W1-W2 [-0.5/2.8]?=- W1-W2 color index (W1-W2)
307-309 A3 --- AGN75 AGN selection at the 75% reliability
threshold (WISEAGN75) (8)
311-313 A3 --- AGN90 AGN selection at the 90% reliability
threshold (WISEAGN90) (8)
315-325 E11.6 mW/m2 F0.5-2 [0/5.2e-13]?=- X-ray flux in the 0.5-2keV
band from LaMassa+ (2016, J/ApJ/817/172)
(Soft_flux)
327-336 F10.5 --- Sdet [0/7556]?=- Significance of X-ray detection
in the soft band (Soft_DETML) (9)
338-347 F10.5 [10-7W] Lx0.5-2 [39.87/45.61]?=- Log of the k-corrected
soft-band X-ray luminosity (Soft_Lum) (10)
349-359 E11.6 mW/m2 F2-10 [0/1.3e-12]?=- X-ray flux in the 2-10 (2-7)
keV band for XMM-Newton (Chandra) sources
from LaMassa+ (2016, J/ApJ/817/172)
(Hard_flux)
361-370 F10.5 --- Hdet [0/2165]?=- Significance of X-ray detection
in the hard band (Hard_DETML) (9)
372-381 F10.5 [10-7W] Lx2-10 [41.05/45.84]?=- Log of the k-corrected
hard-band X-ray luminosity (Hard_Lum) (10)
383-393 E11.6 mW/m2 F0.5-10 [0/1.7e-12]?=- X-ray flux in the 0.5-10
(0.5-7) keV band for XMM-Newton (Chandra)
sources from LaMassa+ (2016, J/ApJ/817/172)
(Full_flux)
395-404 F10.5 --- Fdet [0/9276]?=- Significance of X-ray detection
in the full band (Full_DETML) (9)
406-415 F10.5 [10-7W] Lx0.5-10 [40.37/45.94]?=- Log of the k-corrected
full-band X-ray luminosity (Full_Lum) (10)
417-426 F10.5 [10-7W] Lx [40.19/45.84]?=- Estimate of the k-corrected
2-10keV X-ray luminosity (Xray_Lum) (11)
428-430 A3 --- AGNx X-ray AGN if Lx>1042erg/s (Xray_AGN)
432-441 F10.5 --- logNII/Ha [-1.32/0.21]?=- Logarithm of the
[NII]6584Å/Hα ratio
(NII6584/Halpha) (12)
443-452 F10.5 --- logOIII/Hb [-0.76/1.22]?=- Logarithm of the
[OIII]5007Å/Hα ratio
(OIII5007/Hbeta) (12)
454-457 A4 --- Class BPT classification of sources
(BPT_Classification) (13)
--------------------------------------------------------------------------------
Note (1): If spectrum was derived from the SDSS-IV eBOSS Stripe 82X program,
it was vetted or independently determined by visual inspection.
Note (2): Classification as follows:
GALAXY = galaxy; only narrow emission lines or absorption lines are
present (1466 occurrences)
NELG = emission line galaxy (1 occurrence)
QSO = quasar; if at least one broad emission line is
present (3306 occurrences)
QSO_BAL = broad absorption line quasar (5 occurrences)
STAR = star (65 occurrences)
Note (3): Reference as follows:
eBOSS_S82X = eBOSS spectroscopic survey of Stripe 82X,
described in this paper (1723 occurrences);
SDSS_DR14 = SDSS Data Release 14 (Abolfathi+ 2018ApJS..235...42A 2018ApJS..235...42A);
SDSS_DR14Q = SDSS Quasar Catalog Data Release 14 (Paris+ 2018, VII/286);
SDSS_DR13 = SDSS Data Release 13 (Albareti+ 2017ApJS..233...25A 2017ApJS..233...25A);
SDSS_DR12 = SDSS Data Release 12 (Alam+ 2015, V/147);
SDSS_DR12Q = SDSS Quasar Catalog Data Release 12 (Paris+ 2017, VII/279);
SDSS_DR8 = SDSS Data Release 8 (Aihara+ 2011ApJS..193...29A 2011ApJS..193...29A);
SDSS_DR7Q = SDSS Quasar Catalog DR7 (Schneider+, 2010, VII/260);
SDSSzwarningverifiedbyeye = SDSS zwarning flag was nonnull, but spectrum
was vetted in the catalog release of
LaMassa+ (2016, J/ApJ/817/172);
pre-BOSS = pre-BOSS pilot survey using Hectospec
on MMT (Ross+ 2012, J/ApJS/199/3);
2SLAQ = 2SLAQ survey (Croom+ 2009, J/MNRAS/392/19);
6dF = 6dF survey (Jones+ 2004MNRAS.355..747J 2004MNRAS.355..747J and 2009, VII/259);
HYDRA2014Jan = follow-up observations of Stripe 82X sources from
WIYN HYDRA in 2014 January, first published
in LaMassa+ (2016, J/ApJ/817/172);
HYDRA2015Jan = follow-up observations of Stripe 82X sources from
WIYN HYDRA in 2015 January, first published
in LaMassa+ (2016, J/ApJ/817/172);
GeminiGNIRS2015 = follow-up observations of obscured AGN candidates
in Stripe 82X from Gemini GNIRS in 2015, first published
in LaMassa+ (2017ApJ...847..100L 2017ApJ...847..100L);
DBSP2015Sep = follow-up observations of Stripe 82X sources from
Palomar DoubleSpec in 2015 September, published here
for the first time (1 occurrence);
DBSP2016Aug = follow-up observations of Stripe 82X sources from
Palomar DoubleSpec in 2016 August, published here
for the first time (1 occurrence);
DBSP2017Oct = follow-up observations of Stripe 82X sources from
Palomar DoubleSpec in 2017 October, published here
for the first time (4 occurrences);
KeckLRISOct2017 = follow-up observations of Stripe 82X sources from
Keck LRIS in 2017 October, published here
for the first time (2 occurrences).
Note (4): Code as follows:
-999 = Non applicable (3124 occurrences)
2 = one emission/absorption line identified (165 occurrences)
3 = ≥2 emission/absorption lines identified (1558 occurrences)
Note (5): SExtractor "AUTO" (i.e., Kron-line elliptical aperture) magnitude
from coadded J14 (Jiang+ 2014ApJS..213...12J 2014ApJS..213...12J) catalog (AB) or SDSS ModelMag
photometric measurement.
Note (6): Reference as follows:
J14 = coadded catalog of Jiang+ (2014ApJS..213...12J 2014ApJS..213...12J) (4664 occurrences)
SDSS = pipeline photometry from the single-epoch SDSS cat. (183 occurrences)
Note (7): WISE magnitude measured with profile-fitting photometry (Vega).
Only reported if magnitude has an S/N≥2.
Note (8): If WISE W1-W2 color obeys the Assef+ (2018, J/ApJS/234/23) AGN
selection at the 75% or 90% reliability threshold, this flag is set to "YES".
Note (9): Significance of X-ray detection, where detml=-lnPrandom, with
Prandom as the Poissonian probability that the detection is a random
fluctuation.
Note (10): Only computed if detection significance >10.
Note (11): If "Hdet" (Hard_DETML)>10, this value represents the measured
k-corrected hard X-ray luminosity.
Otherwise, if "Fdet" (Full_DETML)>10, the k-corrected full-band
luminosity is adjusted by a factor of 0.665 to convert to the 2-10keV
band luminosity.
If both Hard_DETML and Full_DETML are below 10, the k-corrected
soft-band luminosity is scaled by a factor of 1.27 to convert to the
2-10keV band luminosity.
Note (12): Only populated for z<0.5 sources spectroscopically identified as
"Galaxies" in the SDSS pipeline with an S/N>5 in the [NII]6584Å,
[OIII]5007Å, Hα, and Hβ lines. Emission line fluxes are
measured by the SDSS pipeline.
Note (13): BPT classification of sources at z<0.5 that are classified as
"Galaxies" in the SDSS pipeline, and with emission line fluxes
significant at the 5σ level. Code as follows:
Sy2 = Seyfert 2 galaxy (122 occurrences) based on the definition of
Kewley+ (2001ApJ...556..121K 2001ApJ...556..121K);
Comp = Composite galaxy (184 occurrences) with emission line ratios between
the theoretical starburst line of Kewley+ (2001ApJ...556..121K 2001ApJ...556..121K) and
empirical dividing line of Kauffmann+ (2003MNRAS.346.1055K 2003MNRAS.346.1055K);
SF = Star-forming galaxies (264 occurrences) with emission line ratios
below the Kauffmann+ (2003MNRAS.346.1055K 2003MNRAS.346.1055K) demarcation.
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History:
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(End) Emmanuelle Perret [CDS] 06-Oct-2020