J/MNRAS/464/3431 Extremely red quasars in BOSS (Hamann+, 2017)
Extremely red quasars in BOSS.
Hamann F., Zakamska N.L., Ross N., Paris I., Alexandroff R.M.,
Villforth C., Richards G.T., Herbst H., Brandt W.N., Cook B., Denney K.D.,
Greene J.E., Schneider D.P., Strauss M.A.
<Mon. Not. R. Astron. Soc., 464, 3431-3463 (2017)>
=2017MNRAS.464.3431H 2017MNRAS.464.3431H (SIMBAD/NED BibCode)
ADC_Keywords: QSOs ; Redshifts ; Equivalent widths
Keywords: galaxies: active - quasars: absorption lines -
quasars: emission lines - quasars: general
Abstract:
Red quasars are candidate young objects in an early transition stage
of massive galaxy evolution. Our team recently discovered a population
of extremely red quasars (ERQs) in the Baryon Oscillation
Spectroscopic Survey (BOSS) that has a suite of peculiar emission-line
properties including large rest equivalent widths (REWs), unusual
'wingless' line profiles, large NV/Lyα, NV/CIV, SiIV/CIV
and other flux ratios, and very broad and blueshifted [OIII]
λ5007. Here we present a new catalogue of CIV and NV
emission-line data for 216188 BOSS quasars to characterize the ERQ
line properties further. We show that they depend sharply on
UV-to-mid-IR colour, secondarily on REW(CIV), and not at all on
luminosity or the Baldwin Effect. We identify a 'core' sample of 97
ERQs with nearly uniform peculiar properties selected via
i-W3≥4.6(AB) and REW(CIV)≥100Å at redshifts 2.0-3.4. A broader
search finds 235 more red quasars with similar unusual
characteristics. The core ERQs have median luminosity
<logL(ergs/s)≳47.1, sky density 0.010deg-2, surprisingly flat/blue
UV spectra given their red UV-to-mid-IR colours, and common outflow
signatures including BALs or BAL-like features and large CIV
emission-line blueshifts. Their SEDs and line properties are
inconsistent with normal quasars behind a dust reddening screen. We
argue that the core ERQs are a unique obscured quasar population with
extreme physical conditions related to powerful outflows across the
line-forming regions. Patchy obscuration by small dusty clouds could
produce the observed UV extinctions without substantial UV reddening.
Description:
Our starting point is the BOSS quasar catalogue for Data Release 12
(hereafter DR12Q; Paris et al., 2014, Cat. VII/270), 2016, Cat.
VII/279). From this sample, we develop a new catalogue of CIV and NV
emission-line data for 216188 quasars in the redshift range
1.53≤ze≤5.0.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 83 97 Core ERQ properties
tableb1.dat 83 235 ERQ-like quasars
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See also:
VII/270 : SDSS quasar catalog: tenth data release (Paris+, 2014)
VII/279 : SDSS quasar catalog: twelfth data release (Paris+, 2017)
Byte-by-byte Description of file: table2.dat tableb1.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- QSO Quasar name (JHHMMSS.ss+DDMMSS.s)
20 A1 --- n_QSO [ab] Note on QSO (1)
22- 25 F4.2 --- ze Best available emission-line redshift from
DR12Q (Paris et al., Cat. VII/270 (Section 3).
27- 30 F4.1 mag imag i magnitude corrected for Galactic extinction
32- 34 F3.1 mag i-W3 ? i-W3 colour index corrected for
Galactic extinction
36- 38 I3 0.1nm REW Rest equivalent width of CIV emission line
40- 41 I2 0.1nm e_REW rms uncertainty on REW
43- 46 I4 km/s FWHM FWHM of CIV emission line
48- 50 I3 km/s e_FWHM rms uncertainty on FWHM
52- 55 F4.2 --- kt80 Kurtosis index of CIV emission line (2)
57- 60 F4.2 --- NV/CIV Line flux ratio NV/CIV
62 I1 --- BAL [0/1] Visual inspection flag (balflagvi)
from DR12Q (3)
64- 68 F5.2 --- alpha ? UV continuum slope all from our emission
line catalogue (αλ
70- 73 F4.2 mag E(B-V) ? Selective extinction derived from r, i, z-W1
colours by Hamann et al. (in preparation).
75- 78 F4.2 mag e_E(B-V) ? rms uncertainty on E(B-V)
80- 83 F4.1 mJy FFIRST ? FIRST 20cm radio flux (4)
84- 85 A2 --- n_FFIRST [ND] ND when non-detection with 5σ
upper limit ∼1mJy
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Note (1): Note as follows:
a = These quasars are in the Ross et al. (2015MNRAS.453.3932R 2015MNRAS.453.3932R) ERQ sample
b = These quasars are in DR12Q (Paris et al., 2017, Cat. VII/279)
but not in our emission line catalogue
Note (2): characterizes the profile shape in terms of the width of the line core
relative to the wings. Specifically, this index measures the velocity width
at 80 per cent of the peak height divided by the width at 20 per cent, e.g.
kt80=Δv(80%)/Δv(20%).
Note (3): Visual inspection flag as follows:
1 = BAL is present
0 = BAL not present
Note (4): where no entry means the source was not covered by FIRST,
0.0 indicates a non-detection with 5σ upper limit ∼1mJy
(Becker, White & Helfand, 1995ApJ...450..559B 1995ApJ...450..559B; Helfand, White & Becker,
2015, Cat. VIII/92), non-zero entries are measurements with SNR>3 as
recorded in DR12Q.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 25-May-2018