J/ApJ/671/1355 EGRET blazars in VIPS (Taylor+, 2007)
Characteristics of EGRET blazars in the VLBA Imaging and
Polarimetry Survey (VIPS).
Taylor G.B., Healey S.E., Helmboldt J.F., Tremblay S., Fassnacht C.D.,
Walker R.C., Sjouwerman L.O., Pearson T.J., Readhead A.C.S., Weintraub L.,
Gehrels N., Romani R.W., Michelson P.F., Blandford R.D., Cotter G.
<Astrophys. J., 671, 1355-1364 (2007)>
=2007ApJ...671.1355T 2007ApJ...671.1355T
ADC_Keywords: Radio sources ; QSOs ; BL Lac objects ; Redshifts
Keywords: catalogs - galaxies: active - galaxies: jets - galaxies: nuclei -
radio continuum: galaxies - surveys - techniques: image processing
Abstract:
We examine the radio properties of EGRET-detected blazars observed as
part of the VLBA Imaging and Polarimetry Survey (VIPS). VIPS has a
flux limit roughly an order of magnitude below the MOJAVE survey and
most other samples that have been used to study the properties of
EGRET blazars. At lower flux levels, radio flux density does not
directly correlate with gamma-ray flux density. We do find that the
EGRET-detected blazars tend to have higher brightness temperatures,
greater core fractions, and possibly larger than average jet opening
angles. A weak correlation is also found with jet length and with
polarization. All of the well-established trends can be explained by
systematically larger Doppler factors in the gamma-ray-loud blazars,
consistent with the measurements of higher apparent velocities found
in monitoring programs carried out at radio frequencies above 10 GHz.
Description:
We have compared the latest EGRET catalog (Hartman et al. 1999, Cat.
J/ApJS/123/79) to the recently compiled Combined Radio All-Sky
Targeted Eight GHz Survey (CRATES; Healey et al. 2007, Cat.
J/ApJS/171/61), and from the intersection compiled a sample of 173
candidate EGRET sources at |b|>10°.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 85 31 EGRET Identifications
table2.dat 105 25 VIPS source properties
table3.dat 61 25 Brightness temperatures of VIPS blazars
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See also:
VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998)
J/ApJS/123/79 : Third EGRET catalog (3EG) (Hartman+, 1999)
J/ApJS/175/97 : CGRaBS: survey of γ-ray blazar candidates (Healey+, 2008)
J/MNRAS/326/1455 : The CLASS blazar survey. I. (Marcha+, 2001)
J/MNRAS/329/877 : The CLASS blazar survey. II. (Caccianiga+, 2002)
J/MNRAS/348/937 : The CLASS blazar survey. III. (Caccianiga+, 2004)
J/ApJ/590/109 : Gamma-ray blazar in northern sky (Sowards-Emmerd+, 2003)
J/ApJS/171/61 : All-Sky Survey of Flat-Spectrum Radio Sources (Healey+ 2007)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- 3EG 3EG name based on EGRET coordinates (JHHMM+DDMM)
12- 21 A10 --- VIPSt VIPS name based on CLASS coordinates (JHHMM+DDMM)
23- 28 F6.1 mJy F8.4GHz 8.4GHz flux density from CLASS
30- 35 F6.3 --- alpha Spectral index between 1.4GHz-NVSS (Condon 1998,
Cat. VIII/65) and 8.4GHz-CLASS
[S(ν){prot.to}{vu}α]
37- 41 F5.3 --- DTS Measure of the positional correspondence of the
radio source to the peak of gamma-ray flux (1)
43- 48 F6.3 --- FoM Figure of merit (Sowards-Emmerd et al. 2003,
Cat. J/ApJ/590/109) of radio-γ association
50 I1 --- Code [1/3] Association code (2)
52- 55 F4.1 mag mag ? Optical magnitude of the host galaxy
57- 61 F5.3 --- z ? Redshift from Veron-Cetty and Veron
(2006, Cat. VII/248)
63- 66 A4 --- Type flat-spectrum radio quasar (FSRQ) or
BL Lac object (BLL)
68- 73 A6 --- CGRaBS CGRaBS if the source is included in the CBRaBS
sample (Healey et al., 2008, J/ApJS/175/97)
75- 85 A11 --- VIPS VIPS source name (JHHMMm+DDMM), as in table2
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Note (1): Lower values indicate a better positional correspondence
(see Sowards-Emmerd et al., 2003, Cat. J/ApJ/590/109).
Note (2): Code is a classification of the same type as in Sowards-Emmerd et al.
(2003, Cat. J/ApJ/590/109) as follows:
3 = sources with FoM>1.0 were deemed "likely" counterparts
1 = sources with 0.25<FoM<1.0 were deemed plausible counterparts
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq VIPS source number
6- 16 A11 --- VIPS VIPS source name (JHHMMm+DDMM)
18- 19 I2 h RAh Right ascension (J2000.0)
21- 22 I2 min RAm Right ascension (J2000.0)
24- 30 F7.4 s RAs Right ascension (J2000.0)
32 A1 --- DE- Declination sign (J2000.0)
33- 34 I2 deg DEd Declination (J2000.0)
36- 37 I2 arcmin DEm Declination (J2000.0)
39- 44 F6.3 arcsec DEs Declination (J2000.0)
46- 55 A10 "YYYY/MM/DD" Date UT Date
57- 62 F6.1 mJy F8.5GHz Flux density at 8.5GHz from the CLASS
survey
64- 69 F6.1 mJy F5GHz Total cleaned flux density from the 5GHz
VLBA map
71- 76 F6.1 mJy F5max Peak flux density from the 5GHz VLBA map
(in mJy/beam)
78- 81 F4.2 mJy noise rms noise of the 5GHz VLBA image
(in mJy/beam)
83 I1 --- Ngc Number of dominant Gaussian components (1)
85- 88 A4 --- Type Source type derived from the automated
Gaussian component classification (2)
90- 93 F4.1 mas Rad Mean radius (3)
95- 98 F4.1 mas Dmax ? Maximum separation among the dominant
Gaussian components
100-105 F6.1 deg PAjet ? Jet position angle (measured from north
through east)
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Note (1): The number of dominant Gaussian components (i.e., that contain
more than 95% of the total flux) fit to the 5GHz VLBA map (see Sect.
2.3 of Helmbolt et al. 2007ApJ...658..203H 2007ApJ...658..203H).
Note (2): see Sect. 2.3 of Helmbolt et al. 2007ApJ...658..203H 2007ApJ...658..203H; classes are:
PS = pointlike sources;
SJET = core short jets (<6mas)
LJET = core long jets (>6mas)
CSO = compact symmetric object candidates;
CPLX = complex sources.
Note (3): The mean radius (i.e., mean distances from the mean component
position) for the ensemble of dominant Gaussian components.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq VIPS source number
6- 16 A11 --- VIPS VIPS source name (JHHMMm+DDMM)
18- 23 F6.1 mJy F5c 5GHz flux density of the core
25 A1 --- l_Dc Limit flag on Dc
26- 30 F5.3 mas Dc FWHM of the core component estimated using a
circular Gaussian fit to the visibility data
32 A1 --- l_TBc Limit flag on TBc
33- 40 E8.3 K TBc Mean brightness temperature of the core
42- 48 E7.3 K TBj ? Mean brightness temperature of the brightest
component outside the core
50- 55 F6.2 deg DPA ? Difference between the outer and inner
position angles of the jet for sources with
more than two jet components
57- 61 F5.2 deg Psi ? Jet opening half-angle for sources with more
than two jet components
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 24-Mar-2010