J/ApJ/780/73 Redshifts of BL Lac objects from Fermi (Ajello+, 2014)
The cosmic evolution of Fermi BL Lacertae objects.
Ajello M., Romani R.W., Gasparrini D., Shaw M.S., Bolmer J., Cotter G.,
Finke J., Greiner J., Healey S.E., King O., Max-Moerbeck W.,
Michelson P.F., Potter W.J., Rau A., Readhead A.C.S., Richards J.L.,
Schady P.
<Astrophys. J., 780, 73 (2014)>
=2014ApJ...780...73A 2014ApJ...780...73A
ADC_Keywords: Active gal. nuclei ; BL Lac objects ; Gamma rays ; Redshifts
Keywords: cosmology: observations - diffuse radiation - galaxies: active -
galaxies: jets - gamma rays: diffuse background - surveys
Abstract:
Fermi has provided the largest sample of γ-ray-selected blazars
to date. In this work we use a uniformly selected set of 211 BL
Lacertae (BL Lac) objects detected by Fermi during its first year of
operation. We obtained redshift constraints for 206 out of the 211 BL
Lac objects in our sample, making it the largest and most complete
sample of BL Lac objects available in the literature. We use this
sample to determine the luminosity function of BL Lac objects and its
evolution with cosmic time. We find that for most BL Lac classes the
evolution is positive, with a space density peaking at modest redshift
(z~1.2). Low-luminosity, high-synchrotron-peaked (HSP) BL Lac
objects are an exception, showing strong negative evolution, with
number density increasing for z≲0.5. Since this rise corresponds to a
drop-off in the density of flat-spectrum radio quasars (FSRQs), a
possible interpretation is that these HSPs represent an
accretion-starved end state of an earlier merger-driven gas-rich
phase. We additionally find that the known BL Lac correlation between
luminosity and photon spectral index persists after correction for the
substantial observational selection effects with implications for the
so-called "blazar sequence." Finally, by estimating the beaming
corrections to the luminosity function, we find that BL Lac objects
have an average Lorentz factor of γ=6.1-0.8+1.1, and that
most are seen within 10° of the jet axis.
Description:
In this work we use a uniformly selected set of 211 BL Lacertae (BL
Lac) objects detected by Fermi during its first year of operation
(Abdo et al. 2010, J/ApJS/188/405). Using the full range of techniques
(see Rau et al. 2012, J/A+A/538/A26; Shaw et al. 2013, J/ApJ/764/135),
we have obtained spectroscopic redshifts or limits for the great
majority (∼98%) of the sources.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 90 211 The 211 BL Lac objects detected by Fermi used
for this analysis (2015-09-08 version)
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See also:
J/A+A/562/A64 : Fermi detection of BL Lac objects (Wu+, 2014)
J/ApJS/209/34 : The first Fermi-LAT >10GeV catalog (1FHL) (Ackermann+, 2013)
J/MNRAS/430/2464 : The CLASS BL Lac sample (Marcha+, 2013)
J/ApJ/764/135 : Spectroscopic redshifts of BL Lac objects (Shaw+, 2013)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/ApJ/753/83 : Associations to 1FGL sources (Ackermann+, 2012)
J/ApJ/748/68 : WISE IR colors of gamma-ray blazars (D'Abrusco+, 2012)
J/ApJ/748/49 : 1LAC broad-line blazars optical spectroscopy (Shaw+, 2012)
J/A+A/538/A26 : BL Lac objects beyond z=1.3 (Rau+, 2012)
J/ApJ/743/171 : The 2LAC catalog (Ackermann+, 2011)
J/ApJ/742/66 : New Fermi/LAT extragalactic sources (Teng+, 2011)
J/ApJ/715/429 : First Fermi-LAT AGN catalog (1LAC) (Abdo+, 2010)
J/ApJS/188/405 : Fermi-LAT first source catalog (1FGL) (Abdo+, 2010)
J/ApJ/699/603 : Evolution of Swift/BAT blazars (Ajello+, 2009)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- --- [1FGL]
6- 17 A12 --- 1FGL Name in the First Fermi-LAT catalog
(1FGL; Abdo et al. 2010, J/ApJS/188/405)
19- 23 F5.2 10-4/m2/s F100 [0.1/44] Flux in the 0.1-100GeV band in
units of 10-8photons/cm2/s (1)
25- 28 F4.2 10-4/m2/s e_F100 Uncertainty in F100
30- 33 F4.2 --- Gamma [1.4/2.8] Photon index Γ (1)
35- 38 F4.2 --- e_Gamma [0/0.33] Uncertainty in Gamma
40- 44 F5.3 --- zsp [0.03/1.4]? Spectroscopic redshift (2)
46 A1 --- r_zsp [h] "h" indicates a spectroscopic redshift
from Pita et al. (2012AIPC.1505..566P 2012AIPC.1505..566P)
48- 51 F4.2 --- zph [1.2/1.7]? Photometric redshift estimate
from Rau et al. 2012 (J/A+A/538/A26)
53 A1 --- r_zph [i] The flag "i" indicates a photometric
redshift from the work of J. Bolmer et al.
(2013, in preparation)
55- 58 F4.2 --- E_zph [0.04]? Positive error in zph
60- 63 F4.2 --- e_zph [0.1]? Negative error in zph
65- 68 F4.2 --- zsp0 [0.1/1.8]? Spectroscopic redshift lower
limit (3)
70 A1 --- r_zsp0 [h] The flag "h" indicates lower limit on
spectroscopic redshift from Pita et al.
(2012AIPC.1505..566P 2012AIPC.1505..566P)
72- 75 F4.2 --- zsp1 [1.6/4.7]? Spectroscopic redshift upper
limit from Shaw et al. 2013 (J/ApJ/764/135)
77- 80 F4.2 --- zph1 [1.0/3.1]? Photometric redshift upper limit
from Rau et al. 2012 (J/A+A/538/A26)
82 A1 --- r_zph1 [i] The flag "i" indicates upper limit on
photometric redshift from the work of
J. Bolmer et al. (2013, in preparation)
84- 90 A7 --- SED SED class (HSP, ISP or LSP) (4)
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Note (1): We note that fluxes and photon indices reported there are those
measured with the pipeline developed by Abdo et al. (2010ApJ...720..435A 2010ApJ...720..435A)
and thus, while compatible with the values reported in the 1FGL catalog
(Abdo et al. 2010, J/ApJS/188/405), they are not exactly the same.
Note (2): As reported in Abdo et al. 2010 (J/ApJ/715/429), Ackermann et al.
2011 (J/ApJ/743/171), Shaw et al. 2012 (J/ApJ/748/49), and Shaw
et al. 2013 (J/ApJ/764/135).
Note (3): From Shaw et al. 2013 (J/ApJ/764/135) and Shaw et al.
(2013AJ....146..127S 2013AJ....146..127S).
Note (4): BL Lac objects and blazars classification based on the frequency, in
the rest frame, of the peak of the synchrotron component as reported in
Ackermann et al. 2011 (J/ApJ/743/171) and Shaw et al. 2013
(J/ApJ/764/135):
HSP = High-Synchrotron-Peaked BL Lac object (νSpeak>1015Hz);
ISP = Intermediate-Synchrotron-Peaked BL Lac object
(1014Hz<νSpeak<1015Hz);
LSP = Low-Synchrotron-Peaked BL Lac object (νSpeak<1014Hz).
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History:
* 29-Jan-2015: From electronic version of the journal (ISP reported both for
LSP and ISP in SED column of table5)
* 08-Sep-2015: Corrected version of table5 from the author (Ajello Marco)
containing the three SED classes (HSP, ISP, and LSP)
(End) Sylvain Guehenneux [CDS] 29-Jan-2015