Rise and Fall of the X-Rise and Fall of the X-ray flash 080330: an ray flash 080330: an

off-axis jet?off-axis jet?

Rise and Fall of the X-Rise and Fall of the X-ray flash 080330: an ray flash 080330: an

off-axis jet?off-axis jet?

C.Guidorzi 1,2,3

on behalf of a large collaboration of the on behalf of a large collaboration of the Swift, Swift, Liverpool and Faulkes Telescopes, GROND, Liverpool and Faulkes Telescopes, GROND,

NOT, REM, TAROTNOT, REM, TAROT teams teamsand in particular S. Kobayashi and J. Granotand in particular S. Kobayashi and J. Granot

C.Guidorzi 1,2,3

on behalf of a large collaboration of the on behalf of a large collaboration of the Swift, Swift, Liverpool and Faulkes Telescopes, GROND, Liverpool and Faulkes Telescopes, GROND,

NOT, REM, TAROTNOT, REM, TAROT teams teamsand in particular S. Kobayashi and J. Granotand in particular S. Kobayashi and J. Granot

11INAF-Osservatorio Astronomico Brera, ItalyINAF-Osservatorio Astronomico Brera, Italy22Astrophysics Research Institute, Liverpool John Moores Astrophysics Research Institute, Liverpool John Moores

University, UKUniversity, UK33Physics Dept. University of Ferrara, ItalyPhysics Dept. University of Ferrara, Italy

11INAF-Osservatorio Astronomico Brera, ItalyINAF-Osservatorio Astronomico Brera, Italy22Astrophysics Research Institute, Liverpool John Moores Astrophysics Research Institute, Liverpool John Moores

University, UKUniversity, UK33Physics Dept. University of Ferrara, ItalyPhysics Dept. University of Ferrara, Italy

Egypt 2009 2

OutlineOutline

X-Ray Flashes (XRFs) as a class of GRBs

XRF 080330: broadband data setObserved properties:

prompt -ray emissionBroadband (X-ray,UV,B,V,r,i,z,J,H,Ks)

afterglow (light curves, SED)

Interpretation of XRF 080330 properties

X-Ray Flashes (XRFs) as a class of GRBs

XRF 080330: broadband data setObserved properties:

prompt -ray emissionBroadband (X-ray,UV,B,V,r,i,z,J,H,Ks)

afterglow (light curves, SED)

Interpretation of XRF 080330 properties

Egypt 2009 3

X-ray Flashes (XRFs)X-ray Flashes (XRFs)

A softer and less energetic version of classical GRBs

(Heise et al. 2001; Kippen et al. 2001)

A softer and less energetic version of classical GRBs

(Heise et al. 2001; Kippen et al. 2001)

e.g.Ep vs. Eiso relation(Amati et al. 2008)

Egypt 2009 4

XRFs vs. c-GRBsXRFs vs. c-GRBs

=Overall, same prompt temporal

propertiesOn average, same afterglow properties

(although see Sakamoto et al. 2008 and the Swift sample)

Associations (or lack of) with hypernovae

≠XRFs are softer, due to a lower Ep (≤ 30

keV), while c-GRBs have Ep of a few 100 keV.

In some cases, less energetic and smoother -ray light curves (e.g. 060218, Campana et al., 2006)

=Overall, same prompt temporal

propertiesOn average, same afterglow properties

(although see Sakamoto et al. 2008 and the Swift sample)

Associations (or lack of) with hypernovae

≠XRFs are softer, due to a lower Ep (≤ 30

keV), while c-GRBs have Ep of a few 100 keV.

In some cases, less energetic and smoother -ray light curves (e.g. 060218, Campana et al., 2006)

Egypt 2009 5

F Peak Energy: EpF Peak Energy: Ep

Sakamoto et al. 2008

XRF

XRR

GRB

Egypt 2009 6

XRF 080330XRF 080330

Swift-BAT (15-150 keV) detected and promptly localised it.

Swift-XRT and UVOT promptly followed it up and began at 77 sec post trigger time X-ray and UV afterglow.

Several robotic facilities promptly reacted and discovered the rising optical counterpart: in particular, 2-m class telescopes (GROND, and LT).

Swift-BAT (15-150 keV) detected and promptly localised it.

Swift-XRT and UVOT promptly followed it up and began at 77 sec post trigger time X-ray and UV afterglow.

Several robotic facilities promptly reacted and discovered the rising optical counterpart: in particular, 2-m class telescopes (GROND, and LT).

Egypt 2009 7

-ray prompt emission

-ray prompt emission

Egypt 2009 8

-ray prompt emission-ray prompt emission

Swift-BAT (15-150 keV) detected and promptly localised it.

Swift-BAT (15-150 keV) detected and promptly localised it.

1. Ep < 35 keV

2. 4 pulses

3. Marginal soft-to-hard evolution, from 2 to 1.5

4. S(15-150 keV)= 3.6 x 10-7 erg cm-2

5. Eiso < 2.2 x 1052 ergs

XRTXRT

Egypt 2009 9

Panchromatic Light curves (from

30 s out to a few days

post burst)

Panchromatic Light curves (from

30 s out to a few days

post burst)

Egypt 2009 10

X-ray NIR Light CurveX-ray NIR Light Curve

Shallo

w o

ptical

rise

Shallo

w o

ptical

rise

FF oo(t)

(t)

t t+0.

5+0.

5

Egypt 2009 11

Spectral Energy Distributions: 1 , 2

Spectral Energy Distributions: 1 , 2

ox = 0.74 ± 0.03

Typical Band fit

Egypt 2009 12

X-ray NIR Light CurveX-ray NIR Light Curve

Plat

eau

at

ever

y

Egypt 2009 13

SED 3: a single unextinguished PL!

SED 3: a single unextinguished PL!

ox = 0.79 ±0.01

Egypt 2009 14

Decay and late-time red Bump (at

1 day)

Decay and late-time red Bump (at

1 day)

Egypt 2009 15

At 1 day it got redder!At 1 day it got redder!

Red b

ump

o = 1.05 ± 0.06

Egypt 2009 16

-Did you -Did you measure z?measure z?-Yes, we did.-Yes, we did.

-Did you -Did you measure z?measure z?-Yes, we did.-Yes, we did.

Egypt 2009 17

z = 1.51z = 1.51

NOT: absorption spectrumNOT: absorption spectrum

Taken att=46 min

Egypt 2009 18

Multi-band simultaneous Modeling

Multi-band simultaneous Modeling

F(t) t- 1 -0.62 0.153 1.14 3.5

F(t) t- 1 -0.42 2.0t1 600 st2 34 ks

Egypt 2009 19

Main Properties: Summary

Main Properties: Summary

Soft, long 4-pulsed event.X-ray steep decay is high-latitude

emission of the last pulse end of the prompt emission

Long plateau (typical X-rays, not so much in optical), single PL spectrum with almost no dust: Av<0.02

Rise-plateau-decay is ACHROMATICRed bump at 1 day

Soft, long 4-pulsed event.X-ray steep decay is high-latitude

emission of the last pulse end of the prompt emission

Long plateau (typical X-rays, not so much in optical), single PL spectrum with almost no dust: Av<0.02

Rise-plateau-decay is ACHROMATICRed bump at 1 day

Egypt 2009 20

InterpretationInterpretation(s)(s)

InterpretationInterpretation(s)(s)

Egypt 2009 21

Interpretation(s)Interpretation(s)

Does the optical rise mark the afterglow onset? No, too slow!

Achromatic evolution geometry jet(s)

How many jets? With just one jet, red bump is the reverse shock of a late energy injection episode.

2 is also OK (e.g. see 080319B), but more contrived! Mind Okkham’s razor!

Does the optical rise mark the afterglow onset? No, too slow!

Achromatic evolution geometry jet(s)

How many jets? With just one jet, red bump is the reverse shock of a late energy injection episode.

2 is also OK (e.g. see 080319B), but more contrived! Mind Okkham’s razor!

Egypt 2009 22

Off-axis jet Off-axis jet

Granot et al. 2005obs 2 0 , (0 few degrees)

Egypt 2009 23

Why does the Sphynx look so tiny?

Maybe you’re anoff-axis observer…