J/A+A/683/A157 QSOs redshifts and photometry (Vejlgaard+, 2024)
Absence of radio-bright dominance in a near-infrared selected sample of
red quasars.
Vejlgaard S., Fynbo J.P.U., Heintz K.E., Krogager J.K., Moller P.,
Geier S.J., Christensen L., Ma G.
<Astron. Astrophys. 683, A157 (2024)>
=2024A&A...683A.157V 2024A&A...683A.157V (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Active gal. nuclei ; Radio sources ; Photometry ; Optical ;
Infrared
Keywords: quasars: general - quasars: supermassive black holes -
galaxies: active - radio-continuum: galaxies
Abstract:
The dichotomy between red and blue quasars is still an open question.
It is debated whether red quasars are simply blue quasars that are
observed at certain inclination angles or if they provide insight into
a transitional phase in the evolution of quasars.
We investigate the relation between quasar colors and radio-detected
fraction because radio observations of quasars provide a powerful tool
in distinguishing between quasar models.
We present the eHAQ+GAIA23 sample, which contains quasars from the
High A(V) Quasar (HAQ) Survey, the Extended High A(V) Quasar (eHAQ)
Survey, and the Gaia quasar survey. All quasars in this sample have
been found using a near-infrared color selection of target candidates
that have otherwise been missed by the Sloan Digital Sky Survey
(SDSS). We implemented a redshift-dependent color cut in g'-i' to
select red quasars in the sample and divided them into redshift bins,
while using a nearest neighbors algorithm to control for luminosity
and redshift differences between our red quasar sample and a selected
blue sample from the SDSS.Within each bin, we cross-matched the
quasars to the Faint Images of the Radio Sky at Twenty centimeters
(FIRST) survey and determined the radio-detection fraction.
For redshifts 0.8<z≤1.5, the red and blue quasars have a
radio-detection fraction of 0.153+0.037-0.032 and
0.132+0.034-0.030, respectively. The red and blue quasars with
redshifts 1.5<z≤2.4 have radio-detection fractions of
0.059+0.019-0.016 and 0.060+0.019-0.016, respectively, and the
red and blue quasars with redshifts z>2.4 have radio-detection
fractions of 0.029+0.017-0.012 and 0.058+0.024-0.019,
respectively. For the WISE color-selected red quasars, we find a
radio-detection fraction of 0.160+0.038-0.034 for redshifts
0.8<z≤1.5, 0.063+0.020-0.017 for redshifts 1.5<z≤2.4, and
0.051+0.030-0.022 for redshifts z>2.4. In other words, we find
similar radio-detection fractions for red and blue quasars within
<1σ uncertainty, independent of redshift. This disagrees with
what has been found in the literature for red quasars in SDSS. It
should be noted that the fraction of broad absorption line (BAL)
quasars in red SDSS quasars is about five times lower. BAL quasars
have been observed to be more frequently radio quiet than other
quasars, therefore the difference in BAL fractions could explain the
difference in radio-detection fraction.
The dusty torus of a quasar is transparent to radio emission. When we
do not observe a difference between red and blue quasars, it leads us
to argue that orientation is the main cause of quasar redness.
Moreover, the observed higher proportion of BAL quasars in our dataset
relative to the SDSS sample, along with the higher rate of radio
detections, indicates an association of the redness of quasars and the
inherent BAL fraction within the overall quasar population. This
correlation suggests that the redness of quasars is intertwined with
the inherent occurrence of BAL quasars within the entire population of
quasars. In other words, the question why some quasars appear red or
exhibit BAL characteristics might not be isolated; it could be
directly related to the overall prevalence of BAL quasars in the
quasar population. This finding highlights the need to explore the
underlying factors contributing to both the redness and the frequency
of BAL quasars, as they appear to be interconnected phenomena.
Description:
Spectroscopic redshift and astrometric and photometric data of the 534
total quasars in the eHAQ-GAIA23 sample. The reference column displays
both the original sample paper and whether (p) or not (u) the quasar
has been published before.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 350 534 Spectroscopic redshift and astrometric and
photometric data
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Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [0/534] Sequential number
5- 24 A20 --- Name Name
26- 38 F13.9 deg RAdeg Right ascension (J2000)
40- 53 F14.9 deg DEdeg Declination (J2000)
55- 57 F3.1 --- QSO [1] is a QSO ?
59- 61 F3.1 --- BAL [0/1] is a BAL ?
63- 65 F3.1 --- RED [0/1] is a red-QSO ?
67- 69 F3.1 --- FIRST [0/1] is FIRST detected ?
71- 76 F6.2 mJy Fint1.4 ?=0 FIRST integrated flux
80- 84 F5.3 --- z Redshift
86- 96 F11.6 mag umag ?=9999 SDSS u (3543Å) band magnitude
98-108 F11.6 mag e_umag ?=9999 rms uncertainty on umag
110-118 F9.6 mag gmag SDSS g (4770Å) band magnitude
120-128 F9.6 mag e_gmag rms uncertainty on gmag
130-138 F9.6 mag rmag SDSS r (6231Å) band magnitude
140-148 F9.6 mag e_rmag rms uncertainty on rmag
150-158 F9.6 mag imag SDSS i (7623Å) band magnitude
160-168 F9.6 mag e_imag rms uncertainty on imag
170-178 F9.6 mag zmag SDSS z (9124Å) band magnitude
180-188 F9.6 mag e_zmag rms uncertainty on zmag
190-200 F11.6 mag Ymag ?=9999 UKIDSS Y band magnitude
202-212 F11.6 mag e_Ymag ?=9999 rms uncertainty on Ymag
214-224 F11.6 mag Jmag ?=9999 UKIDSS J band magnitude
226-236 F11.6 mag e_Jmag ?=9999 rms uncertainty on Jmag
238-248 F11.6 mag Hmag ?=9999 UKIDSS H band magnitude
250-260 F11.6 mag e_Hmag ?=9999 rms uncertainty on Hmag
262-272 F11.6 mag Kmag ?=9999 UKIDSS K band magnitude
274-284 F11.6 mag e_Kmag ?=9999 rms uncertainty on Kmag
286-294 F9.6 mag W1mag WISE W1 magnitude
296-301 F6.2 mag e_W1mag rms uncertainty on W1mag
303-308 F6.3 mag W2mag WISE W2 magnitude
310-316 F7.2 mag e_W2mag ?=9999 rms uncertainty on W2mag
318-323 F6.3 mag W3mag WISE W3 magnitude
325-331 F7.2 mag e_W3mag ?=9999 rms uncertainty on W3mag
333-337 F5.3 mag W4mag WISE W4 magnitude
339-345 F7.2 mag e_W4mag ?=9999 rms uncertainty on W4mag
347-350 A4 --- Ref References (1)
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Note (1): displays both the original sample paper and whether (p) or not (u)
the quasar has been published before.
F13 = Fynbo et al., 2013ApJS..204....6F 2013ApJS..204....6F)
H20 = Heintz et al., 2020A&A...644A..17H 2020A&A...644A..17H, Cat. J/A+A/644/A17
K16 = Krogager et al., 2016ApJ...832...49K 2016ApJ...832...49K
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Acknowledgements:
Johan Fynbo, jfynbo(at)nbi.ku.dk
(End) Patricia Vannier [CDS] 26-Jan-2024