1Sylvio Klose, Thüringer Landessternwarte Tautenburg, Germany

Short bursts -- an observational perspective

2

4 mag

+/- 2 mag

Kann & Klose (2007)

short afterglows: the typical light curve

long vs. shortafterglows:typically dm >~ 4 mag

• be fast• go deep

3

4

• dust and gas

• the outflow geometry

• extra light

Outline of the talk

5

Challenge 1

the GRB environment(dust & gas)

6

(A) long bursts

Kann, Klose, & Zeh (2006)

• inspired by GRB 970828 (Groot et al. 1998)• starting with Ramaprakash et al. (1998)

I. Photometry: GRB host extinctions*** ***

7

(A) long bursts

Kann, Klose, & Zeh (2006)GRB 970828: Djorgovski et al. (2001)

pre-Swift era

8

Fox et al. (2005)

GRB 050709

GRB 050709GRB 060121

(B) short bursts

de Ugarte Postigo et al. (2006);Berger et al. (2006)

4.6?

Multi-color data from short burst afterglows

mostly very bad sampled

1

9

(B) short bursts

• GRB 050709: A_V = (0.67 +/- 0.19) mag (Ferrero et al. 2007a)• GRB 060121: A_V = (0.5 +/- 0.2 ) mag (de Ugarte Postigo et al. 2006)

GRB host extinctions

current situation: not satisfactory

10

ANDICAM

GROND

in perspective: multi-color imaging

2 channels

7 channels

Gamma-Ray Burst Optical Near-Infrared Detector

11

5 m

in

30 m

in

1 m

in

(A) long bursts II. Spectroscopy: early spectra*** ***

060607A, VLT, 8 min

060418, VLT, 10 min

061121, Keck, 14 min

12

(B) short bursts Early spectra from short burst afterglows?

(no spectra at all)

current situation: not satisfactory

1 m

in

5 m

in

30 m

in

13

Calar Alto 3.5-m, PMAS/PPak

(B) short bursts Observing with Integral Field Units

in perspective:

GRB 060605

Ferrero, Savaglio et al. (2007b)

star

star

star

ag

74“ x 64“

3D cube

14

Challenge 2

afterglow geometry, jets

15

(A) long bursts I. Photometry

• starting with GRB 990123 (Castro-Tirado et al. 1999)• and later GRB 990510

• first summarized by Frail et al. (2001)• Panaitescu & Kumar (2001)• Bloom et al. (2003)• and others

*** ***

16

(A) long bursts Light curve breaks in long burst afterglows

Castro-Tirado et al. (1999) Stanek et al. (1999)

GRB 990123

R band

B,V,R,I bands

GRB 990510

17

Zeh, Klose, & Kann (2006)

(A) long bursts Light curve breaks in long burst afterglows

pre-Swift era

Klose et al. (2004)

GRB 030226

UBVRIJHK bands

18

long bursts

short bursts

Watson et al. (2006)

α = 1

see also Livio & Waxman (2000); Rosswog & Ramirez-Ruiz (2003); Janka et al. (2006)

(B) short bursts

0512

21A

, 061

006,

061

210

????4 mag

Light curve breaks in short burst afterglows

Berger (2007)

in perspective:

current situation: not satisfactory

19

GRB 990123: Hjorth et al. (1999)GRB 990510: Covino et al. (1999); Wijers et al. 1999GRB 990712: Rol et al. (2000)

GRB 020813: Gorosabel et al. (2004); Lazzati et al. (2004)GRB 021004: Rol et al. (2004)

GRB 030226: Klose et al. (2004)GRB 030329: Greiner et al. (2003)

GRB 060218: Gorosabel et al. (2006)

list is incomplete

Polarisation data for long burst afterglows

(A) long bursts II. Polarimetry*** ***

20

Lazzati et al. (2004)Gorosabel et al. (2004)

GRB 020813

21

Greiner et al. (2003)R = 15.0t = 2040 secdP= 0.09 %

R = 20.6t = 9600 secdP= 0.48 %

VLT 8.2-m

GRB 030329

(A) long bursts The best sampled polarimetric light curve

22

(B) short bursts

R (t=0.01 days) = 19.5R (t=1 day) = 24.5R (t=10 days) = 27.0

Polarimetric data from short burst afterglows?

in perspective:

23

Challenge 3

extra light, SNe

24

I. Mini-supernovae (Li & Paczynski 1998)

z = 0.1β = 1/3

1

2

3

4

5

6

f = E_rad / Mc**2M = ejected mass

(B) short bursts *** ***

(1)(2)

(3)(4)

(5)(6)

25

Short bursts, afterglows and upper limits

D.A. Kann

26

GRB 050509B (no detected afterglow)

Observational constraints on the LP model

day 20

see also Hjorth et al. (2005)

(B) short bursts

in perspective:

day 1

current situation: strong constraints

27

II. SN 1998bw light

Zeh, Klose, & Hartmann (2004)

(A) long bursts

• starting with GRB 980326 (Bloom et al. 1998)• inspired by GRB 980425/ SN 1998bw (Galama et al., Kulkarni et al. 1998)

*** ***

28Ferrero et al. (2006), incl. data fromRichardson, Branch, & Baron (2006)

The GRB-SNe luminosity distribution(A) long bursts

extinction corrected

SN 1991D SN 1992ar

SN 1987K

GRB 991208

SN 1998bw

GRB 060218(SN 2006aj)

GRB 000911H_0 =71Ω _m = 0.27Ω_Λ = 0.73

29

Kann & Klose (2007)

k = 0.0060

k = 0.0015

k = 0.60

k = 0.29

(B) short bursts Constraints on SN 1998bw light

k < 0.001 ?

30

SN 1998bw peak magnitude (z)

k=0.001

k=1.0

VLT/FORS1, R-band, exposure times (seconds), S/N = 10

(B) short bursts What are the chances to detect SN light?

in perspective:

current situation: deep limits

31

Summary

32

10 yearsGRB afterglows 1997 - 2007

33

„How can I get so much observing time?“

Challenge 4

34

Short burst afterglows, an optical perspective

• obtaining multicolor imaging data (UBVRIJHK) is surely possible

• getting (early-time) spectra is possible

• setting constraints on extra light down to deep flux limits is possible; but the perspectives for detecting something are an open question

• detecting / constraining a light curve break in the optical bands might be hard

• obtaining a polarimetric light curve might be impossible at all

z, gas

dust

jets

mor

e an

d m

ore

diffi

cult

SNe

Anyway, we will try.