New type of long GRBs with additional maxima on the

temporal profiles in the high energy gamma-band

A. Zenin, I. Arkhangelskaja, D. Kirin and E. Voevodina

National Research Nuclear University “MEPhI” Moscow, 2012

Saturday, April 22, 2023 ECRS 2012

High energy gamma-ray bursts observations:

1991–1999 — CRGO: OSSE 0.05–10 MeV COMPTEL 0.7–30 MeVEGRET/TASCS 1-200 MeVEGRET/spark chambers 0.02-30 GeVBATSE (SD&LAD) 0.01-10 MeV2001–2005 — CORONAS-F: AVS-F 0.1–250 MeV SONG 0.05–150 MeVIRIS 0.1–10 MeVHELICON 0.1–10 MeV 2007–present day— AGILE:GRID 0.03-30 GeV calorimeter (2007) 0.25-200 MeV 2008–present day — Fermi:GBM 0.008-40 MeVLAT 0.1-100 GeV Saturday, April 22, 2023 ECRS 2012

AGILE и Fermi (GLAST) characteristics []:

Observatory AGILE Fermi

Device GRID Super-AGILE MC NaI(Tl) BGO LAT

Effective area, cm2

1444 300 ~400 127 12 127 2 8000

Temporal resolution, μs

2 4 3 <10

Field of view, sr 3 9 2.4

Energy range, MeV

30 – 50 000

0.015 – 0.045 0.3 – 100 0.008 – 1 0.15 – 30 20 –300 000

Saturday, April 22, 2023 ECRS 2012

ECRS 2012 Saturday, April 22, 2023

Extended high-energy emission first detection: GRB940217 (BATSE trigger №2831, t90 ~150 s.) Gamma-emission (> 50 MeV) up to 1.5 hours after burst starts, maximum registered energy 18GeV (Hurley K et al., 1994, IAU Circ., 5940, 1)

Temporal profiles of GRB 080825C, GRB 090510 and GRB 0909026B.(a) LAT data (Ghisellini G, et al 2010 MN RAS 403 926-37); (b) GBM data.

ECRS 2012 Saturday, April 22, 2023

ECRS 2012 Saturday, April 22, 2023

The temporal profiles of GRB090323, GRB090328 by Fermi/LAT data (Ghisellini G, et al 2010 MN RAS 403 926-37) and Fermi/GBM data.

The arrows have shown t90 on GBM data.

The temporal profiles of GRB090626, GRB091031 by Fermi/LAT data (Ghisellini G, et al 2010 MN RAS 403 926-37) and Fermi/GBM data.

The arrows have shown t90 on GBM data.ECRS 2012 Saturday, April 22, 2023

typical spectra: BAND model (Band D et al 1993 ApJ 413 1 281-29)

model parameters:A- amplitude, photons-1cm-2keV-1;

α - low-energy spectral index;β - high-energy spectral index;

Epeak - energy of spectral maximum, keV.if

if

ECRS 2012 Saturday, April 22, 2023

GRB spectral evolution for GRB910927

gamma-ray burst parameter evolution (data were taken from Bin-Bin Zhang, Bing et al, 2011 arXiv:1009.3338v2) :

a) new burst subclass b) “usual” GRB

ECRS 2012 Saturday, April 22, 2023

Conclusion

•temporal profiles of GRB090323, GRB090328, GRB090626 and GRB091031 have additional maxima after low-energy t90 intervals finished;•these maxima preceded of faint peaks in low energy bands close to the ends of t90 intervals in low energy band;• parameter evolution are different in comparision to usual gamma-ray bursts.

These features of GRB090323, GRB090328, GRB090626 and GRB091031 allow us to make conclusion that those events could be separated as a new subclass of long bursts with extended high energy γ-emission.

. Saturday, April 22, 2023 ECRS 2012

Saturday, April 22, 2023 ECRS 2012