testing the blast wave model with swift grbs peter a. curran mullard space science laboratory, ucl...

Testing the blast wave model with Swift GRBs

Peter A. CurranMullard Space Science Laboratory, UCL

withRLC Starling, AJ van der Horst,

A Kamble, RAMJ Wijers, M de Pasquale & M Page

pre-Swift versus Swift GRBs

pre-Swift versus Swift GRBs

pre-Swift (GRB 990510)

(Kuulkers et al. 2000)

X-ray

Optical

pre-Swift (GRB 990510) Swift era (GRB

070107)

(Evans et al. 2007)

(Kuulkers et al. 2000)

X-ray

Optical

X-ray only

pre-Swift versus Swift GRBs

pre-Swift (GRB 990510) Swift era (GRB

070107)

(Evans et al. 2007)

(Kuulkers et al. 2000)

X-ray

Optical

pre-Swift versus Swift GRBs

Does pre-Swift theory work?

X-ray only

The blast wave model

(CXC/M. Weiss)

The blast wave model

(CXC/M. Weiss)

k – circumburst density profile (ρ ~ r-k)

The blast wave model

(CXC/M. Weiss)

k – circumburst density profile (ρ ~ r-k)

q – continued energy injection

index (E ~ tq)

The blast wave model

(CXC/M. Weiss)

p – electron energy distribution (Fermi; dN/dE ~ E-

p)

k – circumburst density profile (ρ ~ r-k)

q – continued energy injection

index (E ~ tq)

Synchrotron spectra

(Sari et al. 1998)

Synchrotron spectra

Optical / X-ray

(Sari et al. 1998)

Derivation of p

α ➝ p(α,k,q) & accuracy of temporal fit⇒ multiple options

Derivation of p

α ➝ p(α,k,q) & accuracy of temporal fit⇒ multiple options

βopt ➝ p(βopt,EB-V) ⇒ multiple options

Derivation of p

α ➝ p(α,k,q) & accuracy of temporal fit⇒ multiple options

βopt ➝ p(βopt,EB-V) ⇒ multiple options

βX ➝ p(βX,NH) ⇒ multiple options

Derivation of p

α ➝ p(α,k,q) & accuracy of temporal fit⇒ multiple options

βopt ➝ p(βopt,EB-V) ⇒ multiple options

βX ➝ p(βX,NH) ⇒ multiple options⇒ above/below synchrotron cooling

frequency

Derivation of p

Sample of 10 Swift GRB afterglows

Sample of 10 Swift GRB afterglows

(GRB 060729)

X-ray

Optical

Consistent with the

blast wave model?

(GRB 060729)

X-ray

Optical

Sample of 10 Swift GRB afterglows

Blast wave interpretations

Compare possible multi-wavelength interpretations with blast wave†...

(†Nousek et al. 2006; Starling et al. 2008)

Blast wave interpretations

Compare possible multi-wavelength interpretations with blast wave†...

8/10 consistent with blast wave

4/10 unambiguous jet breaks

6/10 calculated k

3/10 require q ; 3/10 don’t

6/10 unambiguous p 4 above cooling break 2 below cooling break

(†Nousek et al. 2006; Starling et al. 2008)

(Curran et al. 2009)

k

Circumburst density profile, k

(Curran et al. 2009)

(Curran et al. 2009)

Circumburst density profile, k

Wind

(Curran et al. 2009)

Wind

ISM

Circumburst density profile, k

(Curran et al. 2009)

Wind

ISM

Circumburst density profile, k

Not consistent with only one of ISM or

Wind

q

Energy injection index, q

(Curran et al. 2009)

E ~ tq

Energy injection index, q

(Curran et al. 2009)

E ~ tq

Energy injection index, q

(Curran et al. 2009)

E ~ tq

Energy injection index, q

(Curran et al. 2009)

E ~ tqRequired but inconclusive..

.so far

p

Distribution of p

(Curran et al. 2009)

(Curran et al. 2009)

Distribution of p

Not consistent with a single, universal

value

Distribution of p

βX

Distribution of p

Distribution of spectral index, β

below cooling break

above cooling break

Distribution of spectral index, β

(Curran et al. in prep; data from Evans et al. 2009)

Distribution of spectral index, β

(Curran et al. in prep; data from Evans et al. 2009)

Distribution of spectral index, β

(Curran et al. in prep; data from Evans et al. 2009)

Most X-rays above cooling break?

Conclusions

8 out of 10 GRBs favour the blast wave model*

(*or at least don't disfavour it)

k is not consistent with only one of ISM or Wind

q is required in some bursts, inconclusive so far

• p is not consistent with a single, universal value

Most X-rays above the cooling break?