J/MNRAS/438/3058 15GHz variability of γ-ray blazars (Richards+, 2014)
Connecting radio variability to the characteristics of gamma-ray blazars.
Richards J.L., Hovatta T., Max-Moerbeck W., Pavlidou V., Pearson T.J.,
Readhead A.C.S.
<Mon. Not. R. Astron. Soc., 438, 3058-3069 (2014)>
=2014MNRAS.438.3058R 2014MNRAS.438.3058R
ADC_Keywords: BL Lac objects ; QSOs ; Gamma rays ; Radio sources
Keywords: galaxies: active - BL Lacertae objects: general - quasars: general -
radio continuum: galaxies
Abstract:
We present results from four years of twice-weekly 15GHz radio
monitoring of about 1500 blazars with the Owens Valley Radio
Observatory 40m telescope. Using the intrinsic modulation index to
measure variability amplitude, we find that, with >6σ
significance, the radio variability of radio-selected γ-ray-loud
blazars is stronger than that of γ-ray-quiet blazars. Our extended
data set also includes at least 21 months of data for all AGN with
'clean' associations in the Fermi Large Area Telescope First AGN
Catalog, 1LAC. With these additional data, we examine the radio
variability properties of a γ-ray-selected blazar sample. Within
this sample, we find no evidence for a connection between radio
variability amplitude and optical classification. In contrast, for our
radio-selected sample we find that the BL Lac object subpopulation is
more variable than the flat-spectrum radio quasar (FSRQ)
subpopulation. Radio variability is found to correlate with the
synchrotron peak frequency, with low- and
intermediate-synchrotron-peaked blazars varying more than
high-synchrotron-peaked ones. We find evidence for a significant
negative correlation between redshift and radio variability among
bright FSRQs.
Description:
In this paper, we report results based on the four years of data
collected between 2008 January 1 and 2011 December 31, inclusive.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 85 1413 Source properties and results
table2.dat 49 307958 15GHz light-curve data
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See also:
J/ApJS/175/97 : CGRaBS: survey of gamma-ray blazar candidates (Healey+ 2008)
J/ApJ/715/429 : First Fermi-LAT AGN catalog (1LAC) (Abdo+, 2010)
J/ApJ/743/171 : The 2LAC catalog (Ackermann+, 2011)
J/ApJS/194/29 : Observations of blazars at 15GHz (Richards+, 2011)
J/MNRAS/439/690 : Optical/γ-ray variability in blazars (Hovatta+, 2014)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- CGRaBS CGRaBS (J/ApJS/175/97) name (JHHMM+DDMM)
12- 23 A12 --- 1FGL 1FGL name (J/ApJS/188/405) (JHHMM.m+DDMM)
25- 36 A12 --- 2FGL 2FGL name (J/ApJS/199/31) (JHHMM.m+DDMM) (1)
38- 41 A4 --- OptC Optical class: BLL or FSRQ (2)
43- 45 A3 --- SEDC SED class: HSP, ISP or LSP (3)
47- 51 F5.3 --- z [0/5.5]? Redshift
53- 57 F5.3 --- m [0.01/0.67]?=- Intrinsic modulation index (4)
59- 63 F5.3 --- e_m ?=- Error on m (lower value)
65- 69 F5.3 --- E_m ?=- Error on m (upper value)
71 A1 --- l_S0 Limit flag on S0
72- 77 F6.3 Jy S0 [0.02/29]?=- Maximum likelihood mean
15GHz flux density S0
79- 83 F5.3 Jy e_S0 ?=- rms uncertainty on S0
85 A1 --- f_S0 [F] Faint flag (5)
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Note (1): CGRaBS sources with a corresponding entry in the '2FGL name' column
are considered γ-ray loud.
Note (2): Optical classes are:
BLL = BL Lac object
FSRQ = Flat spectrum radio quasar
Note (3): SED classes are:
HSP = high-synchrotron-peaked blazar
ISP = intermediate-synchrotron-peaked blazar
LSP = low-synchrotron-peaked blazar
Note (4): Intrinsic modulation index m defined as m=σ0/S0 where
σ0 is the intrinsic standard deviation and S0 the intrinsic
mean flux density.
Note (5): Sources marked with 'F' are too faint for variability analysis.
The flux density is an upper limit for these sources (l_S0 contains '<')
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 A10 --- CGRaBS CGRaBS name (JHHMM+DDMM)
12- 23 A12 --- 1FGL 1FGL name (JHHMM.m+DDMM)
25- 36 F12.6 d MJD [54470/55927] Modified Julian date
38- 43 F6.3 Jy S15 Flux density at 15GHz
45- 49 F5.3 Jy e_S15 rms uncertainty on S15
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 10-Dec-2014