J/ApJ/764/135 Spectroscopic redshifts of BL Lac objects (Shaw+, 2013)
Spectroscopy of the largest ever γ-ray-selected BL Lac sample.
Shaw M.S., Romani R.W., Cotter G., Healey S.E., Michelson P.F.,
Readhead A.C.S., Richards J.L., Max-Moerbeck W., King O.G., Potter W.J.
<Astrophys. J., 764, 135 (2013)>
=2013ApJ...764..135S 2013ApJ...764..135S
ADC_Keywords: BL Lac objects ; Redshifts ; Spectroscopy ; Gamma rays
Keywords: BL Lacertae objects: general; galaxies: active; gamma rays: galaxies;
quasars: general; surveys
Abstract:
We report on spectroscopic observations covering most of the 475 BL
Lacs in the second Fermi Large Area Telescope (LAT) catalog of active
galactic nuclei (AGNs). Including archival measurements (correcting
several erroneous literature values) we now have spectroscopic
redshifts for 44% of the BL Lacs. We establish firm lower redshift
limits via intervening absorption systems and statistical lower limits
via searches for host galaxies for an additional 51% of the sample
leaving only 5% of the BL Lacs unconstrained. The new redshifts raise
the median spectroscopic {overline}{Z} from 0.23 to 0.33 and include
redshifts as large as z=2.471. Spectroscopic redshift minima from
intervening absorbers have {overline}{Z}, showing a substantial
fraction at large z and arguing against strong negative evolution. We
find that detected BL Lac hosts are bright ellipticals with black hole
masses M•∼108.5-109, substantially larger than the mean
of optical AGNs and LAT Flat Spectrum Radio Quasar samples. A slow
increase in M• with z may be due to selection bias. We find
that the power-law dominance of the optical spectrum extends to
extreme values, but this does not strongly correlate with the
γ-ray properties, suggesting that strong beaming is the primary
cause of the range in continuum dominance.
Description:
Observations were obtained with the Marcario Low Resolution
Spectrograph (LRS) on the Hobby-Eberly Telescope (HET), with the ESO
Faint Object Spectrograph and Camera (EFOSC2) and ESO Multi-Mode
Instrument (EMMI) on the New Technology Telescope at La Silla
Observatory (NTT), with the Goodman High Throughput Spectrograph
(GHTS) on the Southern Astrophysical Research (SOAR) Telescope, with
the Double Spectrograph (DBSP) on the 200" Hale Telescope at Mt.
Palomar, with the Focal Reducer and low dispersion Spectrograph
(FORS2) on the Very Large Telescope at Paranal Observatory (VLT), and
with the Low Resolution Imaging Spectrograph (LRIS) at the W. M. Keck
Observatory (WMKO) with wavelengths range from 3100 to 10500Å and
resolution 4 to 15Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 137 372 BL Lac spectral properties
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See also:
J/A+A/562/A64 : Fermi detection of BL Lac objects (Wu+, 2014)
J/AJ/145/31 : Catalog of X-ray selected BL Lac objects (Kapanadze+, 2013)
J/A+A/538/A26 : BL Lac objects beyond z=1.3 (Rau+, 2012)
J/ApJ/748/49 : Optical spectroscopy of 1LAC broad-line blazars (Shaw+, 2012)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/ApJS/194/45 : QSO properties from SDSS-DR7 (Shen+, 2011)
J/ApJ/743/171 : The 2LAC catalog (Ackermann+, 2011)
J/ApJ/709/1407 : SED of the Fermi blazars (Li+, 2010)
J/AJ/139/390 : Opt. selected BL Lac objects from SDSS-DR7 (Plotkin+, 2010)
J/ApJS/175/97 : Survey of γ-ray blazar candidates (Healey+, 2008)
J/A+A/466/63 : VLBI observations of BL Lac objects (Wu+, 2007)
J/A+A/445/441 : SED of BL Lacertae objects (Nieppola+, 2006)
J/AJ/129/2542 : BL Lac from SDSS (Collinge+, 2005)
J/AJ/129/2138 : Centers of early-type galaxies with HST (Lauer+, 2005)
J/A+A/401/927 : The HRX-BL Lac sample (Beckmann+, 2003)
J/MNRAS/277/1477 : A catalogue of BL Lacertae objects (Padovani+ 1995)
J/A+AS/98/393 : 1Jy BL Lac Objects: Observational Data (Stickel+ 1993)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [2FGL]
6- 17 A12 --- 2FGL 2FGL catalog identifier (JHHMM.m+DDMM)
19- 28 F10.6 deg RAdeg Right Ascension in decimal degrees (J2000)
30- 39 F10.6 deg DEdeg Declination in decimal degrees (J2000)
41- 50 A10 --- Name Source name (JHHMM+DDMM)
52- 56 F5.2 [10uJy] logF log(spectral flux) at ∼598nm (1)
58- 61 F4.2 [10uJy] e_logF Uncertainty in logF
63- 68 F6.3 --- alpha [-6.5/3] Spectral index α (1)
70- 75 F6.3 --- e_alpha ? Uncertainty in alpha
77- 82 F6.2 mag RMag [-24.3/-21]? Absolute R band magnitude
84- 87 F4.2 mag e_RMag [0.08/0.4]? Uncertainty in RMag
89- 93 F5.3 --- z [0.01/2.5]? Spectroscopic redshift
94 A1 --- u_z Systematic uncertainty flag in z; see text
96 A1 --- n_z Redshift method for z (2)
98-102 F5.3 --- zmin ? Spectroscopic lower redshift limit (3)
104-107 F4.2 --- z22.5 ? Minimum redshift assuming MR=-22.5mag
109-112 F4.2 --- z22.9 ? Minimum redshift assuming MR=-22.9mag
114-117 F4.2 --- zmax Spectroscopic upper redshift limit
119-122 A4 --- Type Source type (4)
124-126 A3 --- SED Spectral energy distribution type (5)
128-131 A4 --- Tel Telescope used to obtain the data (6)
133-137 I5 d MJD Modified Julian Date of the observation
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Note (1): Flux at 1014.7Hz∼5980Å, in units of 10-28erg/s/cm2/Hz
[=10-31W/m2/Hz=10-5Jy].
The spectral index α is such that Fν∝να.
Note (2): Method as follows:
B = Broad emission lines;
N = Narrow emission lines;
G = host galaxy features;
S = Special case; see Section 3.1.
Note (3): i.e. from intervening absorption systems.
Note (4): Type as follows:
BLL = BL Lac;
FSRQ = flat spectrum radio quiet source
UNK = Unknown
Note (5): Peak frequency of the SED's synchrotron component. Type as follows:
LBL = Low peak, νpeak<1014Hz.
IBL = Intermediate peak, 1014Hz<νpeak_<10^15Hz.
HBL = High peak, νpeak>1015Hz.
Note (6): Telescope as follows:
SDSS = Sloan Digital Sky Survey.
HET = Marcario Low Resolutin Spectrograph on the Hobby-Eberly Telescope.
P200 = The Double Spectrograph on the 200" Hale Telescope at Mt. Palomar.
SOAR = Goodman High Throughput Spectrograph on the Southern
Astrophysical Research Telescope.
VLT = the FOcal Reducer and low dispersion Spectrograph on the
Very Large Telescope at Paranal Observatory.
WMKO = Low Resolution Imaging Spectrograph at the W. M. Keck Observatory.
NTT = ESO Faint Object Spectrograph and Camera and ESO Multi-Mode
Instrument on the New Technology Telescope at La Silla Observatory.
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History:
From electronic version of the journal
(End) Greg Schwarz [AAS], Emmanuelle Perret [CDS] 27-Oct-2014