Gamma-Ray Bursts observed by XMM-Newton Paul O’Brien X-ray and Observational Astronomy Group, University of Leicester Collaborators:- James Reeves,Darach Watson, Julian Osborne, Ken Pounds, Alex Short, Martin Turner, Mike Watson, Keith Mason, Norbert Schartel, M Santos-Lleo, Matthaus Ehle.
GRB 970228: BeppoSAX Observations X-ray and optical counterparts seen: z=0.695 (Djorgovski et al. 1999) X-RAY IMAGES OF REGION CENTRED ON THE GRB 1997February 28 1997 March 3
Optical Afterglows & Host Galaxies GRB 971214 - Keck GRB 990123 - HST host galaxy GRB
merging neutron star binary collapse of giant star Predicted duration ~ seconds Predicted duration ~ 10s of seconds Possible Models for the Progenitor High energy (high mass), compact objects two leading models Both models produce an accreting black hole or a milli-second pulsar Both models have very high angular momentum Both models give beamed emission Jet internal/external shocks + interaction with surroundings afterglow The models predict different line spectra
XMM-Newton Observation of GRB 011211Reeves et al (2002): Nature, 416, 512Reeves et al (2003): A&A, 403, 463 NOT, R band image XMM-Newton EPIC
Optical Follow-up of GRB 011211 GRB Host Redshift determined as z=2.1400.001 Holland et al. (2002) HST:- GRB host galaxy (Fox 2002)
The X-ray Spectrum of GRB 011211 – first 5 ksec Power-law Fit (=2.2)
Hydrogenic lines from Mg, Si, S, Ar and Ca detected in first 10ksec x10 Solar abundances, but no iron line (<1.4 Solar) – Supernova? Sig. at 99.97% Si XIV Mg XI/XII S XVI Ar XVIII Ca XX Lines are blueshifted: outflow velocity = 26000 km s-1
Why is there no iron line in GRB 011211? Nucleosynthesis Synthesis model for a 40 solar mass progenitor star (e.g. Woosley & Weaver 1995) Iron line only dominates after t > 100 days. Nickel line dominates at t < 10 days.
X-ray afterglow of GRB 001025A - 45 hrs after GRB Watson et al: 2002, A&A, 393, L1 Line emission? Sig. 99.87% Zx = 0.53 +/- 0.03 Soft excess line emission? Fading X-ray source P(const) = 0.002 IPN error box Best PL with Galactic absorption
X-ray afterglow of GRB 010220 - 14.8 hrs after GRB Watson et al: 2002, A&A, 393, L1 Sig. 99.87% Zx = 1.0 +/- 0.05 ‘Fe’ line BeppoSAX error box Assumed afterglow P(const) = 0.06 Best PL with Galactic absorption
X-ray afterglow of GRB 020322 - 14.9 hr after GRB Watson et al: 2002, A&A, 395, L41 7.8 hr observation X-ray source fades as t -1.3 Need intrinsic absorption. At Zabs ~ 1.8, NH~1.3x1022 cm-2 Faint, fading optical transient No thermal emission apparent Excess absorption
Watson et al., 2003, ApJ, 595, L29 GRB 030227 - detection of transient Si, S, Ar, Ca last 10ks only Si S Ar Ca Total flux and line flux variation ~210 line photons (~115 in GRB 011211) K lines from Si, S, Ar and Ca z=1.350.05 Detection significance = 5 No Fe or Ni/Co lines (<1.6 & <18 solar abundances, cf. 24 solar for light elements)
Willingale et al., 2003, MNRAS, submitted GRB 030329 afterglow evolution radio (8.4 GHz) optical (R) Optical + radio excess: Supernova (+?) X-ray (1 keV)
UVOT BAT BAT XRT UVOT XRT Spacecraft Spacecraft Swift –catching gamma ray bursts on the fly GSFC Launch in 2004 BAT 5x sensitivity of BATSE X-ray telescope has a MOS CCD Detect ~150 GRBs/year Response time ~ 100 seconds
Conclusions • Soft X-ray lines detected in most, but not all, XMM-Newton GRB afterglow spectra. • Theoretical models all assume reflection produces lines, but empirical fits prefer thermal models…?? • XMM-Newton EPIC gives ~ x50 the count rate of the BeppoSAX MECS for a typical GRB afterglow spectrum. • XMM-Newton will continue to play an important role in the Swift era– track long-term spectral evolution of the afterglow.