Taking a Broad View of Prompt Emission

Contemporaneous emission at eV and ~0.1 MeV

Sarah Yost, for the ROTSE Collaboration

Venice, June 2006

Key Points prompt : contemporaneous with -rays importance of broadband view

prompt less understood synchrotron emission?

afterglow onset reverse shock

diversity of prompt broadband spectral shapes

diversity of prompt optical lightcurves

I. Spectral Indices in Play

F

(at

low end)

OPT-

Spectral Regions

(1-p)/

2 : slow cool

2 : abs.

1/3 : to peak

-p/2 : above coolin

g

Spectral Regions

1/3 : to peak

2 : abs.

-1/2 :

fast cool

-p/2 : above cooling

:

expectationsOPT- : can’t be

any value

between optical, vs. in

between optical, vs. in

between optical, vs. in

1/3 : to peak

-1/2 : fast cool (1-p)/2 : slow cool -p/2 : above cooling

Relative Spectra

Relative Spectra

Prompt Component(s)

F

• afterglow rise

• Swift X-ray: afterglow not just extension of GRB

II. Prompt Optical Behaviour

Prompt Optical Behaviour

NOT correlated with GRB

optical flux just above GRB spectrum

()

extrapolation

Prompt Optical Behaviour

NOT correlated with GRB

optical flux below GRB spectrum

()

extrapolation

requires GRB spectral rollover

Prompt Optical Behaviour

... but correlated with GRB in some cases.

T-T(GRB) (sec)

Vestrand et al 2005

also seen as an IR flash

Broadband Shape Peak: Anything Goes

high-E -rays (990123) <~ optical (051111) between optical, -rays

optical correlation (041219A), flux level below -ray extrapolation not constant during GRB

cases with afterglow flux below -ray extrapolation (050401, 050319)

Summary no single pattern (, peak of F, afterglow) model(s) must be flexible dearth of reverse shock signatures, 990123 exceptional

afterglow already established during GRB

2nd prompt component evidence in optical as well as X-ray that afterglow≠ GRB extension