J/ApJ/754/121 GRBs from Fermi/GBM and LAT (The Fermi Team, 2012)
Constraining the high-energy emission from gamma-ray bursts with Fermi.
The Fermi Large Area Telescope Team, Ackermann M., Ajello M., Baldini L.,
Barbiellini G., Baring M.G., Bechtol K., Bellazzini R., Blandford R.D.,
Bloom E.D., Bonamente E., Borgland A.W., Bottacini E., Bouvier A.,
Brigida M., Buehler R., Buson S., Caliandro G.A., Cameron R.A., Cecchi C.,
Charles E., Chekhtman A., Chiang J., Ciprini S., Claus R., Cohen-Tanugi J.,
Cutini S., D'ammando F., De Palma F., Dermer C.D., do Couto e Silva E.,
Drell P.S., Drlica-Wagner A., Favuzzi C., Fukazawa Y., Fusco P.,
Gargano F., Gasparrini D., Gehrels N., Germani S., Giglietto N.,
Giordano F., Giroletti M., Glanzman T., Granot J., Grenier I.A.,
Grove J.E., Hadasch D., Hanabata Y., Harding A.K., Hays E., Horan D.,
Johannesson G., Kataoka J., Knodlseder J., Kocevski D., Kuss M., Lande J.,
Longo F., Loparco F., Lovellette M.N., Lubrano P., Mazziotta M.N.,
McEnery J., McGlynn S., Michelson P.F., Mitthumsiri W., Monzani M.E.,
Moretti E., Morselli A., Moskalenko I.V., Murgia S., Naumann-Godo M.,
Norris J.P., Nuss E., Nymark T., Ohsugi T., Okumura A., Omodei N.,
Orlando E., Panetta J.H., Parent D., Pelassa V., Pesce-Rollins M.,
Piron F., Pivato G., Racusin J.L., Raino S., Rando R., Razzaque S.,
Reimer A., Reimer O., Ritz S., Ryde F., Sgro C., Siskind E.J., Sonbas E.,
Spandre G., Spinelli P., Stamatikos M., Stawarz L., Suson D.J.,
Takahashi H., Tanaka T., Thayer J.G., Thayer J.B., Tibaldo L.,
Tinivella M., Tosti G., Uehara T., Vandenbroucke J., Vasileiou V.,
Vianello G., Vitale V., Waite A.P.,
(the Fermi Gamma-ray Burst Monitor Team), Connaughton V., Briggs M.S.,
Guirec S., Goldstein A., Burgess J.M., Bhat P.N., Bissaldi E.,
Camero-Arranz A., Fishman J., Fitzpatrick G., Foley S., Gruber D.,
Jenke P., Kippen R.M., Kouveliotou C., McBreen S., Meegan C.,
Paciesas W.S., Preece R., Rau A., Tierney D., van der Horst A.J.,
von Kienlin A., Wilson-Hodge C., Xiong S.
<Astrophys. J., 754, 121 (2012)>
=2012ApJ...754..121T 2012ApJ...754..121T
ADC_Keywords: Gamma rays
Keywords: gamma-ray burst: general; gamma rays: general
Abstract:
We examine 288 gamma-ray bursts (GRBs) detected by the Fermi Gamma-ray
Space Telescope's Gamma-ray Burst Monitor (GBM) that fell within the
field of view of Fermi's Large Area Telescope (LAT) during the first
2.5 years of observations, which showed no evidence for emission above
100MeV. We report the photon flux upper limits in the 0.1-10GeV range
during the prompt emission phase as well as for fixed 30s and 100s
integrations starting from the trigger time for each burst. We compare
these limits with the fluxes that would be expected from
extrapolations of spectral fits presented in the first GBM spectral
catalog and infer that roughly half of the GBM-detected bursts either
require spectral breaks between the GBM and LAT energy bands or have
intrinsically steeper spectra above the peak of the νFν
spectra (Epk). In order to distinguish between these two scenarios,
we perform joint GBM and LAT spectral fits to the 30 brightest
GBM-detected bursts and find that a majority of these bursts are
indeed softer above Epk than would be inferred from fitting the GBM
data alone. Approximately 20% of this spectroscopic subsample show
statistically significant evidence for a cutoff in their high-energy
spectra, which if assumed to be due to γγ attenuation,
places limits on the maximum Lorentz factor associated with the
relativistic outflow producing this emission. All of these latter
bursts have maximum Lorentz factor estimates that are well below the
minimum Lorentz factors calculated for LAT-detected GRBs, revealing a
wide distribution in the bulk Lorentz factor of GRB outflows and
indicating that LAT-detected bursts may represent the high end of this
distribution.
Description:
We compiled a sample of all GRBs detected by the Fermi Gamma-ray Space
Telescope/Gamma-ray Burst Monitor (GBM) between the beginning of
normal science operations of the Fermi mission on 2008 August 4 up to
2011 January 1, yielding a total of 620 GRBs. Of these, 288 bursts
fell within 65° of the Large Area Telescope (LAT) z-axis (or
boresight) at the time of GBM trigger, which we define as the LAT FOV.
Of the 288 GRBs in our sample, we were able to obtain upper limits, at
95% confidence level (CL), for 270 bursts using the unbinned
likelihood method and 95% CL upper limits for 250 bursts using the
counting method for the T100 intervals derived from the GBM data. See
section 5.1 for further explanations.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 69 277 Burst sample with selected parameters
--------------------------------------------------------------------------------
See also:
J/A+A/559/A9 : Neutrinos from GRBs with ANTARES (Adrian-Martinez+ 2013)
J/ApJS/207/39 : IPN supplement to the Fermi GBM (Hurley+, 2013)
J/ApJS/199/18 : The Fermi GBM catalog (Paciesas+, 2012)
J/A+A/525/A53 : GBM parameters for detected FERMI bursts (Guetta+, 2011)
J/MNRAS/418/2202 : Analysis of γ-ray bursts (Dainotti+, 2011)
J/ApJ/711/495 : Durations of Swift/BAT GRBs (Butler+, 2010)
J/ApJS/166/298 : Spectral cat. of bright BATSE GRBs (Kaneko+, 2006)
J/ApJS/126/19 : BATSE gamma-ray burst spectral catalog. I. (Preece+, 2000)
J/ApJ/446/115 : Gamma ray burst localizations (Vrba+ 1995)
http://fermi.gsfc.nasa.gov/ssc/ : Fermi Science Support Center home page
http://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html : Fermi GBM burst
catalog on line
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I09 --- ID GRB index number (YYMMDDNNN)
(corresponds to trigger name bnYYMMDDNNN)
11- 19 I9 s MET Mission elapsed time relative to
2001 January 1, 0h:0m:0s UTC
21- 26 F6.2 deg RAdeg Right ascension in decimal degrees (J2000)
28- 33 F6.2 deg DEdeg Declination in decimal degrees (J2000)
35- 39 F5.1 deg ePos [0/102.8] Error in decimal degrees
41- 44 F4.1 deg OAA [1.3/64.9] Off-axis angle with respect to
the LAT boresight
46- 50 F5.1 s T100 [0/158] T100 duration
52- 58 F7.1 --- FT100 [0.8/12910]? 95% confidence level photon flux
upper limit for T100 time interval (1)
60- 64 F5.1 --- F30s [2.2/275]? 95% confidence level photon flux
upper limit for 30s time interval (1)
66- 69 F4.1 --- F100s [0.7/100]? 95% confidence level photon flux
upper limit for 100s time interval (1)
--------------------------------------------------------------------------------
Note (1): For both upper limit methods (likelihood and counting), we consider
three time intervals: two fixed intervals of 30 and 100s post-trigger,
and a "T100" interval that is determined through the use of the
Bayesian Blocks algorithm (Jackson et al. 2005ISPL...12..105J 2005ISPL...12..105J) to
estimate the duration of burst activity in the NaI detector that has
the largest signal above background.
See section 4.1 for further explanations.
Photon flux upper limits in the 0.1-10GeV range and
in units of x10-5photons/cm2/s.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 04-Mar-2014