J/MNRAS/452/2553 Sample of foreground-background quasar pairs (Johnson+, 2015)
On the origin of excess cool gas in quasar host haloes.
Johnson S.D., Chen H.-W., Mulchaey J.S.
<Mon. Not. R. Astron. Soc., 452, 2553-2565 (2015)>
=2015MNRAS.452.2553J 2015MNRAS.452.2553J (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Spectroscopy
Keywords: quasars: absorption lines - quasars: general - galaxies: Seyfert
Abstract:
Previous observations of quasar host haloes at z∼2 have uncovered
large quantities of cool gas that exceed what is found around inactive
galaxies of both lower and higher masses. To better understand the
source of this excess cool gas, we compiled an exhaustive sample of
195 quasars at z∼1 with constraints on chemically enriched, cool gas
traced by MgII absorption in background quasar spectra from the Sloan
Digital Sky Survey. This quasar sample spans a broad range of
luminosities from Lbol=1044.4 to 1046.8erg/s and allows an
investigation of whether halo gas properties are connected with quasar
properties. We find a strong correlation between luminosity and cool
gas covering fraction. In particular, low-luminosity quasars exhibit a
mean gas covering fraction comparable to inactive galaxies of similar
masses, but more luminous quasars exhibit excess cool gas approaching
what is reported previously at z∼2. Moreover, 30-40 percent of the
MgII absorption occurs at radial velocities of |Deltav|>300km/s from
the quasar, inconsistent with gas bound to a typical quasar host halo.
The large velocity offsets and observed luminosity dependence of the
cool gas near quasars can be explained if the gas arises from: (1)
neighbouring haloes correlated through large-scale structure at Mpc
scales, (2) feedback from luminous quasars or (3) debris from the
mergers thought to trigger luminous quasars. The first of these
scenarios is in tension with the lack of correlation between quasar
luminosity and clustering while the latter two make distinct
predictions that can be tested with additional observations.
Description:
To compile a large sample of foreground-background quasar pairs
with constraints on MgII absorption, we retrieved a list of the
395281 quasars classified by the SDSS-III automated classification
and redshift measurement pipeline (Bolton et al., 2012AJ....144..144B 2012AJ....144..144B)
as of Data Release 12.
The search yielded a sample of 195 foreground-background quasar
pairs which we visually inspected to ensure that the automated
classifications as broad-line (Type 1) quasars and redshifts from the
SDSS data base are robust.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 74 247 Summary of quasar and absorption properties
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Name Foreground QSO name (JHHMM+DDMM)
12- 13 I2 h RAh Foreground QSO Right ascension (J2000)
15- 16 I2 min RAm Foreground QSO Right ascension (J2000)
18- 22 F5.2 s RAs Foreground QSO Right ascension (J2000)
24 A1 --- DE- Foreground QSO Declination sign (J2000)
25- 26 I2 deg DEd Foreground QSO Declination (J2000)
28- 29 I2 arcmin DEm Foreground QSO Declination (J2000)
31- 34 F4.1 arcsec DEs Foreground QSO Declination (J2000)
36- 41 F6.4 --- z Foreground QSO redshift (1)
43- 46 F4.1 [10-7W] logLbol Bolometric luminosity
48- 51 F4.1 arcsec dtheta Angular separation between the foreground and
background quasars
53- 55 I3 kpc d Distance Projected distance between the
foreground and background quasars
57 A1 --- l_Wr(2796) Limit flag on Wr(2796) (2)
58- 61 F4.2 0.1nm Wr(2796) Rest-frame equivalent width of MgII (2796)
63- 66 F4.2 0.1nm e_Wr(2796) ? rms uncertainty on Wr(2796)
68- 72 I5 km/s dv ?=- Velocity difference between the
foreground and background quasars
74 I1 --- Ref Reference (3)
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Note (1): Quasars with redshifts from narrow [OII] or [OIII] are shown to four
decimal places and three decimal places otherwise.
Note (2): For non-detections, we report 3σ upper limits integrated over
a 250km/s velocity interval.
Note (3): References as follows:
1 = Bowen et al., 2006ApJ...645L.105B 2006ApJ...645L.105B
2 = Farina et al., 2013MNRAS.429.1267F 2013MNRAS.429.1267F, 2014MNRAS.441..886F 2014MNRAS.441..886F
3 = Prochaska et al., 2014ApJ...796..140P 2014ApJ...796..140P
4 = This work
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 04-Feb-2016