J/ApJ/810/L9 1.5Jy MOJAVE AGN sample and 3FGL data (Lister+, 2015)
Why have many of the brightest radio-loud blazars not been detected in
gamma-rays by Fermi?
Lister M.L., Aller M.F., Aller H.D., Hovatta T., Max-Moerbeck W.,
Readhead A.C.S., Richards J.L., Ros E.
<Astrophys. J., 810, L9 (2015)>
=2015ApJ...810L...9L 2015ApJ...810L...9L (SIMBAD/NED BibCode)
ADC_Keywords: Active gal. nuclei ; Radio continuum ; Gamma rays ; Redshifts
Keywords: galaxies: active; galaxies: jets; gamma-ray burst: general;
quasars: general; radio continuum: galaxies
Abstract:
We use the complete MOJAVE 1.5Jy sample of active galactic nuclei
(AGNs) to examine the gamma-ray detection statistics of the brightest
radio-loud blazars in the northern sky. We find that 23% of these AGNs
were not detected above 0.1GeV by the Fermi-LAT during the four-year
3FGL catalog period partly because of an instrumental selection effect
and partly due to their lower Doppler boosting factors. Blazars with
synchrotron peaks in their spectral energy distributions located below
1013.4Hz also tend to have high-energy peaks that lie below the
0.1GeV threshold of the LAT, and are thus less likely to be detected
by Fermi. The non-detected AGNs in the 1.5Jy sample also have
significantly lower 15GHz radio modulation indices and apparent jet
speeds, indicating that they have lower than average Doppler factors.
Since the effective amount of relativistic Doppler boosting is
enhanced in gamma-rays (particularly in the case of external
inverse-Compton scattering), this makes them less likely to appear in
the 3FGL catalog. Based on their observed properties, we have
identified several bright radio-selected blazars that are strong
candidates for future detection by Fermi.
Description:
As part of a Very Long Baseline Array (VLBA) key project to study the
parsec-scale structure and evolution of AGN jets (Lister et al. 2009,
J/AJ/137/3718), we have constructed a complete, flux density-limited
sample, based on all available GHz band flux density data on bright
radio AGNs over a 16 year period from 1994.0 to 2010.0 (Lister et al.
2013, J/AJ/146/120). The MOJAVE 1.5Jy sample includes all AGNs
(excluding gravitational lenses) located north of J2000 declination
-30° that are known to have exceeded 1.5Jy in compact (mas-scale)
15GHz flux density at least once during that period. Using newly
obtained data from the OVRO 15GHz AGN monitoring program (Richards et
al. 2011, J/ApJS/194/29), we have refined our extended flux density
estimates.
The Third Fermi Gamma-ray Catalog (3FGL; Acero et al. 2015,
J/ApJS/218/23) is based on LAT data collected between 2008 August 4
and 2012 July 31 and contains 3033 high-confidence detections above
0.1GeV. The Third LAT AGN Catalog (3LAC; Ackermann et al. 2015,
J/ApJ/810/14) associates 1563 of these sources with AGNs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 88 181 1.5Jy MOJAVE AGN sample properties
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See also:
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
VIII/40 : GB6 catalog of radio sources (Gregory+ 1996)
J/ApJ/810/14 : Third catalog of LAT-detected AGNs (3LAC) (Ackermann+, 2015)
J/MNRAS/450/2658 : Blazars with RATAN-600 flux densities (Mufakharov+, 2015)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
J/ApJS/217/2 : Refined associations of Fermi/LAT sources (Massaro+, 2015)
J/MNRAS/441/1899 : Fermi bright blazars (Fuhrmann+, 2014)
J/MNRAS/438/3058 : 15GHz variability of γ-ray blazars (Richards+, 2014)
J/AJ/146/120 : MOJAVE. X. Parsec-scale kinematics of AGNs (Lister+, 2013)
J/A+A/541/A160 : Planck + X/γ observations of blazars (Giommi+, 2012)
J/ApJ/744/177 : VLBA 5GHz observations of Fermi/LAT AGNs (Linford+, 2012)
J/ApJ/742/27 : 15GHz and jet properties of MOJAVE blazars (Lister+, 2011)
J/ApJ/741/30 : Radio/γ-ray correlation in AGN (Ackermann+, 2011)
J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)
J/ApJ/726/16 : γ-ray loud blazars (Linford+, 2011)
J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)
J/ApJ/722/L7 : Fermi/LAT detected MOJAVE AGNs (Pushkarev+, 2010)
J/ApJ/718/587 : The Fermi-AT20G catalog (Mahony+, 2010)
J/ApJS/188/405 : Fermi-LAT first source catalog (1FGL) (Abdo+, 2010)
J/ApJ/716/30 : SED of Fermi bright blazars (Abdo+, 2010)
J/ApJ/715/429 : First Fermi-LAT AGN catalog (1LAC) (Abdo+, 2010)
J/MNRAS/402/2403 : Australia Telescope 20GHz Survey Catalog (Murphy+, 2010)
J/ApJS/183/46 : Fermi/LAT bright gamma-ray source list (0FGL) (Abdo+, 2009)
J/AJ/137/3718 : 15GHz monitoring of AGN jets with VLBA (Lister+, 2009)
J/AJ/130/1418 : AGN jet kinematics (Jorstad+, 2005)
http://www.physics.purdue.edu/MOJAVE/ : MOJAVE home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID The J2000 identifier (JHHMM+DDMM)
12 A1 --- f_ID [a] a=Low galactic latitude (|b|<10°)
14- 27 A14 --- Alias Other identifier
29- 46 A18 --- Fermi FGL name (3FGL, 1FGL or flag) (1)
48- 55 F8.6 --- z [0.004/3.4]? Redshift
57- 61 F5.2 Jy Sext [0.02/66.1]? Arcsecond-scale 15GHz flux density
63- 67 F5.2 Jy Smax [0.7/33.8] Maximum 15GHz VLBA flux density (2)
69- 73 F5.2 Jy Smed [0.3/23] Median 15GHz VLBA flux density (2)
75- 78 F4.2 --- a [0.3/2.9]? Radio activity index
80- 83 F4.1 [Hz] nuobs [11.8/14.4]? Log observed synchrotron peak
frequency; observer frame
85- 88 F4.1 [Hz] nurest [12.3/14.5]? Log observed synchrotron peak
frequency; rest frame
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Note (1): Flag are:
b = Fermi LAT detection reported by Carpenter et al. (2014ATel.5838....1C 2014ATel.5838....1C);
c = Fermi LAT detection reported by Abdo et al. (2010ApJ...720..912A 2010ApJ...720..912A).
Note (2): During 3FGL time window.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Dec-2015