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.

The Compton Gamma Ray Observatory

GRB 970228: BeppoSAX Observations

1997 February 28 1997 March 3

X-RAY IMAGES OF REGION CENTRED ON THE GRB

X-ray and optical counterparts seen:

z=0.695 (Djorgovski et al. 1999)

Optical Afterglows & Host Galaxies

GRB 971214 - Keck

GRB 990123 - HST

hostgalaxy

GRB

Possible Models for the Progenitor•High energy (high mass), compact objects two leading models

collapse of giant star

Predicted duration ~ seconds

merging neutron star binary

Predicted duration ~ 10s of seconds

• 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 011211

Reeves et al (2002): Nature, 416, 512Reeves et al (2003): A&A, 403, 463

XMM-Newton EPIC

NOT, R band image

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?

Mg XI/XII Si XIV

S XVI

Ar XVIII

Ca XX

Lines are blueshifted: outflow velocity = 26000 km s-1

Sig. at 99.97%

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

Soft excess line emission?

Watson et al: 2002, A&A, 393, L1

Fading X-ray sourceP(const) = 0.002

IPN error box

Best PL with Galactic absorption

Line emission?

Sig. 99.87%

Zx = 0.53 +/- 0.03

‘Fe’ line

X-ray afterglow of GRB 010220 - 14.8 hrs after GRB

BeppoSAX error boxAssumed afterglowP(const) = 0.06 Best PL with Galactic absorption

Sig. 99.87% Zx = 1.0 +/- 0.05

Watson et al: 2002, A&A, 393, L1

X-ray afterglow of GRB 020322 - 14.9 hr after GRB

Excess absorption

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

Watson et al: 2002, A&A, 395, L41

GRB 030227 - detection of transient Si, S, Ar, Ca

last 10ks only

K lines from Si, S, Ar and Ca z=1.350.05

Detection significance = 5No Fe or Ni/Co lines (<1.6 & <18 solar abundances, cf. 24 solar for light elements)

Si S Ar Ca

Total flux and line flux variation

~210 line photons

(~115 in GRB 011211)

Watson et al., 2003, ApJ, 595, L29

XMM-Newton GRB afterglows emission line summary

GRB rest frame interval (d) lines z_X z_AG signif Ref011211 <0.15 - 0.17 H-like Si, S, Ar 1.81+/-.07 2.140 99.97% 1,2001025a <1.2 - >1.4 (H-like Mg, Si, S) 0.53+/-.03 99.87% 3010220 <0.31 - >0.56 "Fe" 1.0+/-.05 99.84% 3020322 (0.22 - 0.34) none 1.8(?) 4030227 0.18 - >0.23 H-like Si, S, He-like Ca 1.35 >99.85% 5030329 (36.3 & 51.7) none 0.1685 6,7

Ref1 Reeves et al Nature 416, 512 (2002)2 Reeves et al A&A 403, 463 (2003)3 Watson et al A&A 393, L1 (2002)4 Watson et al A&A 395, L41 (2002)5 Watson et al ApJLett 595 (2003)6 Willingale et al MNRAS submitted 7 Tiengo et al A&A submitted

GRB 030329 afterglow evolution

X-ray(1 keV)

optical(R)

radio(8.4 GHz)

Optical + radio excess: Supernova (+?)

Willingale et al., 2003, MNRAS, submitted

GSFC

BAT

XRT

Spacecraft

UVOT

BAT

UVOT

XRT

Spacecraft

• Launch in 2004• BAT 5x sensitivity of BATSE• X-ray telescope has a MOS CCD• Detect ~150 GRBs/year• Response time ~ 100 seconds

Swift – catching gamma ray bursts on the fly

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.