J/ApJ/846/34 Flaring gamma-ray sources; LAT 7.4yr (2FAV) (Abdollahi+, 2017)
The second catalog of flaring gamma-ray sources from the Fermi All-sky
Variability Analysis.
Abdollahi S., Ackermann M., Ajello M., Albert A., Baldini L., Ballet J.,
Barbiellini G., Bastieri D., Becerra Gonzalez J., Bellazzini R.,
Bissaldi E., Blandford R.D., Bloom E.D., Bonino R., Bottacini E.,
Bregeon J., Bruel P., Buehler R., Buson S., Cameron R.A., Caragiulo M.,
Caraveo P.A., Cavazzuti E., Cecchi C., Chekhtman A., Cheung C.C., Chiaro G.,
Ciprini S., Conrad J., Costantin D., Costanza F., Cutini S., D'Ammando F.,
de Palma F., Desai A., Desiante R., Digel S.W., Di Lalla N., Di Mauro M.,
Di Venere L., Donaggio B., Drell P.S., Favuzzi C., Fegan S.J., Ferrara E.C.,
Focke W.B., Franckowiak A., Fukazawa Y., Funk S., Fusco P., Gargano F.,
Gasparrini D., Giglietto N., Giomi M., Giordano F., Giroletti M.,
Glanzman T., Green D., Grenier I.A., Grove J.E., Guillemot L., Guiriec S.,
Hays E., Horan D., Jogler T., Johannesson G., Johnson A.S., Kocevski D.,
Kuss M., La Mura G., Larsson S., Latronico L., Li J., Longo F., Loparco F.,
Lovellette M.N., Lubrano P., Magill J.D., Maldera S., Manfreda A., Mayer M.,
Mazziotta M.N., Michelson P.F., Mitthumsiri W., Mizuno T., Monzani M.E.,
Morselli A., Moskalenko I.V., Negro M., Nuss E., Ohsugi T., Omodei N.,
Orienti M., Orlando E., Paliya V.S., Paneque D., Perkins J.S., Persic M.,
Pesce-Rollins M., Petrosian V., Piron F., Porter T.A., Principe G.,
Raino S., Rando R., Razzano M., Razzaque S., Reimer A., Reimer O., Sgro C.,
Simone D., Siskind E.J., Spada F., Spandre G., Spinelli P., Stawarz L.,
Suson D.J., Takahashi M., Tanaka K., Thayer J.B., Thompson D.J.,
Torres D.F., Torresi E., Tosti G., Troja E., Vianello G., Wood K.S.
<Astrophys. J., 846, 34 (2017)>
=2017ApJ...846...34A 2017ApJ...846...34A
ADC_Keywords: Gamma rays ; Active gal. nuclei ; BL Lac objects ; QSOs ;
Cross identifications
Keywords: astroparticle physics; catalogs; galaxies: active;
gamma rays: general; techniques: photometric
Abstract:
We present the second catalog of flaring gamma-ray sources (2FAV)
detected with the Fermi All-sky Variability Analysis (FAVA), a tool
that blindly searches for transients over the entire sky observed by
the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space
Telescope. With respect to the first FAVA catalog, this catalog
benefits from a larger data set, the latest LAT data release (Pass 8),
as well as from an improved analysis that includes likelihood
techniques for a more precise localization of the transients. Applying
this analysis to the first 7.4 years of Fermi observations, and in two
separate energy bands 0.1-0.8GeV and 0.8-300GeV, a total of 4547
flares were detected with significance greater than 6σ (before
trials), on the timescale of one week. Through spatial clustering of
these flares, 518 variable gamma-ray sources were identified. Based on
positional coincidence, likely counterparts have been found for 441
sources, mostly among the blazar class of active galactic nuclei. For
77 2FAV sources, no likely gamma-ray counterpart has been found. For
each source in the catalog, we provide the time, location, and
spectrum of each flaring episode. Studying the spectra of the flares,
we observe a harder-when-brighter behavior for flares associated with
blazars, with the exception of BL Lac flares detected in the
low-energy band. The photon indexes of the flares are never
significantly smaller than 1.5. For a leptonic model, and under the
assumption of isotropy, this limit suggests that the spectrum of
freshly accelerated electrons is never harder than p∼2.
Description:
To build the second catalog of flaring gamma-ray sources (2FAV)
catalog, we apply the Fermi All-sky Variability Analysis (FAVA;
Ackermann+ 2013, J/ApJ/771/57) to the first 387 weeks of Fermi
observations, from Mission Elapsed Time (MET) 239557418 to 473615018,
or Modified Julian Date (MJD) from 54682 (2008 August 4) to 57391
(2016 January 4). In this time range, a total of 7106 seed flares were
found, roughly 18 per week. As for the previous catalog, FAVA uses
weekly time bins. Two independent energy bands are used, 0.1-0.8GeV
and 0.8-300GeV, to enhance the sensitivity to spectrally soft and hard
flares, respectively.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 116 518 List of the second catalog of flaring gamma-ray
sources (2FAV) sources
table4.dat 64 6 List of 2FAV sources that have been associated with
2FGL sources and the possible 3FGL counterpart
of the associations
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See also:
VII/274 : The Roma BZCAT - 5th edition (Massaro+, 2015)
J/ApJS/123/79 : Third EGRET catalog (3EG) (Hartman+, 1999)
J/AJ/133/2487 : VERA 22GHz Fringe Search Survey (Petrov+, 2007)
J/A+A/506/1563 : First AGILE catalog of gamma-ray sources (Pittori+, 2009)
J/ApJ/718/587 : The Fermi-AT20G catalog (Mahony+, 2010)
J/ApJ/722/520 : Gamma-ray light curves of Fermi blazars (Abdo+, 2010)
J/ApJS/188/405 : Fermi-LAT first source catalog (1FGL) (Abdo+, 2010)
J/ApJS/199/31 : Fermi LAT second source catalog (2FGL) (Nolan+, 2012)
J/ApJ/771/57 : FAVA Fermi-LAT flaring gamma-ray sources (Ackermann+, 2013)
J/MNRAS/441/1899 : Fermi bright blazars (Fuhrmann+, 2014)
J/A+A/558/A137 : AGILE bright gamma-ray sources (Verrecchia+, 2013)
J/ApJS/217/2 : Refined associations of Fermi/LAT sources (Massaro+, 2015)
J/ApJS/218/23 : Fermi LAT third source catalog (3FGL) (Acero+, 2015)
J/ApJ/810/14 : Third catalog of LAT-detected AGNs (3LAC) (Ackermann+, 2015)
J/ApJ/838/139 : Radio follow-up on 3FGL unassociated sources (Schinzel+, 2017)
http://fermi.gsfc.nasa.gov/ssc/data/access/lat/fava_catalog/ : 2FAV home page
http://www.asdc.asi.it/fava/ : Online interactive FAVA catalog
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- 2FAV FAVA identification (JHHMM+DD.d)
11 A1 --- f_2FAV [f] f: sources localized solely by the
photometric FAVA analysis
13- 18 F6.2 deg RAdeg Right Ascension of Source (J2000)
20- 25 F6.2 deg DEdeg Declination of Source (J2000)
27- 32 F6.2 deg GLON Galactic Longitude of Source (J2000)
34- 39 F6.2 deg GLAT Galactic Latitude of Source (J2000)
41- 44 F4.2 deg r95 [0.04/1.8] Statistical error on the source
position at 95% confidence level
46- 48 I3 --- Nf [1/301] Total number of flares
50- 51 I2 --- Nhe [0/83] Number of high-energy flares
53- 55 I3 --- Nneg [0/235] Number of negative flares
57- 60 F4.2 deg Rs [0.1/2.3] Search radius used in the
association procedure
62- 79 A18 --- GAssoc Counterpart found in the gamma-ray catalogs
80 A1 --- f_GAssoc [*] *: no significant weekly variability was
detected for the source in the 1FGL, 2FGL, or
3FGL catalogs
82-105 A24 --- Assoc Counterpart at other wavelengths
107-111 A5 --- Class Class of the counterpart (1)
113-116 I4 --- ATel ? ATel number for Fermi-LAT flare alerts
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Note (1): Class of the counterpart (Table 3) as follows:
pwn = Pulsar wind nebula (1 occurrence);
psr = Pulsar (1 occurrence);
agn = Non-blazar active galaxy (2 occurrences);
hmb = High-mass binary (3 occurrences);
rdg = Radio galaxy (3 occurrences);
nlsy1 = Narrow line Seyfert 1 (3 occurrences);
nov = Nova (5 occurrences);
grb = Gamma-ray burst (14 occurrences);
bcu = Blazar candidate of uncertain type (67 occurrences);
bll = BL Lac (73 occcurrences);
fsrq = FSRQ (253 occurrences);
Blank for unassociated sources and unknown classes (93 occurrences).
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- 2FAV Source identifier
12- 15 F4.2 deg Rs [0.1/0.5] Search radius used in the
association procedure
17- 28 A12 --- 2FGL 2FGL counterpart (JHHMM.m+DDMM)
30- 33 F4.2 deg 2Sep [0.02/0.2] 2FGL distance from the 2FAV source
35- 40 F6.2 --- 2Var [15.3/121.3] 2FGL variability index
42- 53 A12 --- 3FGL 3FGL counterpart (JHHMM.m+DDMM)
55- 58 F4.2 deg 3Sep [0.02/0.2]? 3FGL distance from the 2FAV source
60- 64 F5.2 --- 3Var [56.6/66.6]? 3FGL variability index
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History:
From electronic version of the journal
References:
Ackermann et al. 2013ApJ...771...57A 2013ApJ...771...57A Cat. J/ApJ/771/57
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Apr-2018