2009ApJ...706L.138A

Query : 2009ApJ...706L.138A

2009ApJ...706L.138A - Astrophys. J., 706, L138-L144 (2009/November-3)

Fermi observations of GRB 090902B: a distinct spectral component in the prompt and delayed emission.

ABDO A.A., ACKERMANN M., AJELLO M., ASANO K., ATWOOD W.B., AXELSSON M., BALDINI L., BALLET J., BARBIELLINI G., BARING M.G., BASTIERI D., BECHTOL K., BELLAZZINI R., BERENJI B., BHAT P.N., BISSALDI E., BLANDFORD R.D., BLOOM E.D., BONAMENTE E., BORGLAND A.W., BOUVIER A., BREGEON J., BREZ A., BRIGGS M.S., BRIGIDA M., BRUEL P., BURGESS J.M., BURROWS D.N., BUSON S., CALIANDRO G.A., CAMERON R.A., CARAVEO P.A., CASANDJIAN J.M., CECCHI C., CELIK O., CHEKHTMAN A., CHEUNG C.C., CHIANG J., CIPRINI S., CLAUS R., COHEN-TANUGI J., COMINSKY L.R., CONNAUGHTON V., CONRAD J., CUTINI S., D'ELIA V., DERMER C.D., DE ANGELIS A., DE PALMA F., DIGEL S.W., DINGUS B.L., DO COUTO E SILVA E., DRELL P.S., DUBOIS R., DUMORA D., FARNIER C., FAVUZZI C., FEGAN S.J., FINKE J., FISHMAN G., FOCKE W.B., FORTIN P., FRAILIS M., FUKAZAWA Y., FUNK S., FUSCO P., GARGANO F., GEHRELS N., GERMANI S., GIAVITTO G., GIEBELS B., GIGLIETTO N., GIORDANO F., GLANZMAN T., GODFREY G., GOLDSTEIN A., GRANOT J., GREINER J., GRENIER I.A., GROVE J.E., GUILLEMOT L., GUIRIEC S., HANABATA Y., HARDING A.K., HAYASHIDA M., HAYS E., HORAN D., HUGHES R.E., JACKSON M.S., JOHANNESSON G., JOHNSON A.S., JOHNSON R.P., JOHNSON W.N., KAMAE T., KATAGIRI H., KATAOKA J., KAWAI N., KERR M., KIPPEN R.M., KNODLSEDER J., KOCEVSKI D., KOMIN N., KOUVELIOTOU C., KUSS M., LANDE J., LATRONICO L., LEMOINE-GOUMARD M., LONGO F., LOPARCO F., LOTT B., LOVELLETTE M.N., LUBRANO P., MADEJSKI G.M., MAKEEV A., MAZZIOTTA M.N., McBREEN S., McENERY J.E., McGLYNN S., MEEGAN C., MESZAROS P., MEURER C., MICHELSON P.F., MITTHUMSIRI W., MIZUNO T., MOISEEV A.A., MONTE C., MONZANI M.E., MORETTI E., MORSELLI A., MOSKALENKO I.V., MURGIA S., NAKAMORI T., NOLAN P.L., NORRIS J.P., NUSS E., OHNO M., OHSUGI T., OMODEI N., ORLANDO E., ORMES J.F., PACIESAS W.S., PANEQUE D., PANETTA J.H., PELASSA V., PEPE M., PESCE-ROLLINS M., PETROSIAN V., PIRON F., PORTER T.A., PREECE R., RAINO S., RANDO R., RAU A., RAZZANO M., RAZZAQUE S., REIMER A., REIMER O., REPOSEUR T., RITZ S., ROCHESTER L.S., RODRIGUEZ A.Y., ROMING P.W.A., ROTH M., RYDE F., SADROZINSKI H.F.-W., SANCHEZ D., SANDER A., SAZ PARKINSON P.M., SCARGLE J.D., SCHALK T.L., SGRO C., SISKIND E.J., SMITH P.D., SPINELLI P., STAMATIKOS M., STECKER F.W., STRATTA G., STRICKMAN M.S., SUSON D.J., SWENSON C.A., TAJIMA H., TAKAHASHI H., TANAKA T., THAYER J.B., THAYER J.G., THOMPSON D.J., TIBALDO L., TORRES D.F., TOSTI G., TRAMACERE A., UCHIYAMA Y., UEHARA T., USHER T.L., VAN DER HORST A.J., VASILEIOU V., VILCHEZ N., VITALE V., VON KIENLIN A., WAITE A.P., WANG P., WILSON-HODGE C., WINER B.L., WOOD K.S., YAMAZAKI R., YLINEN T. and ZIEGLER M.

Abstract (from CDS):

We report on the observation of the bright, long gamma-ray burst (GRB), GRB 090902B, by the Gamma-ray Burst Monitor (GBM) and Large Area Telescope (LAT) instruments on-board the Fermi observatory. This was one of the brightest GRBs to have been observed by the LAT, which detected several hundred photons during the prompt phase. With a redshift of z = 1.822, this burst is among the most luminous detected by Fermi. Time-resolved spectral analysis reveals a significant power-law component in the LAT data that is distinct from the usual Band model emission that is seen in the sub-MeV energy range. This power-law component appears to extrapolate from the GeV range to the lowest energies and is more intense than the Band component, both below ∼50 keV and above 100 MeV. The Band component undergoes substantial spectral evolution over the entire course of the burst, while the photon index of the power-law component remains constant for most of the prompt phase, then hardens significantly toward the end. After the prompt phase, power-law emission persists in the LAT data as late as 1 ks post-trigger, with its flux declining as t.–1.5. The LAT detected a photon with the highest energy so far measured from a GRB, 33.4+2.7–3.5GeV. This event arrived 82 s after the GBM trigger and ∼50 s after the prompt phase emission had ended in the GBM band. We discuss the implications of these results for models of GRB emission and for constraints on models of the extragalactic background light.

Abstract Copyright: ∼

Journal keyword(s): gamma rays: bursts

CDS comments: GRB 090202B is a misprint for GRB 090902B.

Simbad objects: 8

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Number of rows : 8
N Identifier Otype ICRS (J2000)
RA 		ICRS (J2000)
DEC 		Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2026 		#notes
1 3B 940217 gB 01 56.3 +04 33           ~ 204 0
2 GRB 090328 gB 06 02 39.69 -41 52 55.1           ~ 194 1
3 GRB 080916C gB 07 59 23.24 -56 38 16.8           ~ 386 0
4 Fermi bn090626189 gB 11 20 -33.5           ~ 54 0
5 Fermi bn090323002 gB 12 42 50.28 +17 03 11.9           ~ 244 1
6 Fermi bn090902462 gB 17 39 45.26 +27 19 28.1           ~ 440 0
7 GRB 080514B gB 21 31 22.61 +00 42 30.3           ~ 69 0
8 Fermi bn090510016 G 22 14 12.6230 -26 34 58.550           ~ 548 0

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