# Presentation: 146421

##    Optical Afterglows 

-    Optical Afterglows
- of Gamma-Ray Bursts

**Elena Pian****  - **INAF, Trieste Astronomical Observatory, Italy

- Aspen, 23 February 2007

## Swift Highlights:

- detected so far
- ~100 have a redshift

**Isotropic irradiated ********–ray energy vs redshift**

- GRB050904
- z = 6.29

- _Swift Highlights_:
-  Early optical counterparts with UVOT and ground- based telescopes
-  Optical counterparts of short GRBs (~10)
-  GRB-SN connection: XRF060218, GRB060614

## GRB990123

*Maiorano et al. 2004 *

**GRB990123**

**optical flash**

- z = 1.6

## GRB041219a: Optical flash from internal shocks

*Akerlof et al. 1999; Vestrand et al. 2005; Maiorano et al. 2004;*
*Corsi et al. 2004 *

- RAPTOR
- Internal shock

- ROTSE-I
- Reverse shock

**GRB990123**

## 60cm, ESO, La Silla

## REM light curves of GRB060418 and GRB060607A: determination of the 

- z = 1.48

- z = 3.08

*Molinari et al. 2007*

- REM light curves of GRB060418 and GRB060607A: determination of the
- bulk Lorentz factor

**XRT**

**XRT**

**REM**

**REM**

## VLT-UVES spectra acquired in Rapid Response Mode (RRM)

- Excited levels of Fe II and Ni II vary.  These species are completely ionized at distances less than 1.7 kpc from the GRB
- H I is likely to be ionized at
- Even larger distances

- GRB060418 (z = 1.48)

*Vreeswijk et al. 2007*

## GRB060206: imaging and spectroscopy of a high-redshift 

- z = 4.048

- XRT

*Stanek et al. 2007; Wozniak et al. 2006; Monfardini et al. 2006; Hao et al. 2007 *

- GRB060206: imaging and spectroscopy of a high-redshift
- early optical counterpart

## GRB060206 

- GRB060206
- z = 4.048
- Average spectrum:
- Absorbers at
- Various redshifts
*Hao et al. 2007*

- z = 1.48

- z = 3.54

- z = 4.048

## Hao et al. 2007

*Hao et al. 2007*

## Time dependence of intervening absorption lines

- MgII 2796

- MgII 2803

- FeII 2600

- Line column density combined with GRB beam size yields tight
- constraints on size of the absorber
- This in turn determines the density of the absorber
-   Mg II   0.0015/cm3

*Hao et al. 2007*
*Frank et al. 2007*

## Supernova search in short GRBs

*Soderberg et al. 2006*

*Covino et al. 2005*

- F(mJy)

- GRB051221A  (z = 0.546)

- GRB050709  (z = 0.16)

- R-band

##                    Host Galaxies of Short GRBs

- SFR < 0.03 Msun/yr

*Berger et al. 2005*

*Soderberg et al. 2006*

-                    Host Galaxies of Short GRBs
-                           Morphologies and star formation rates vary widely

- GRB050724 (z = 0.257)

- GRB051221A (z = 0.546)

- SFR = 2 Msun/yr

- SFR < 0.02 Msun/yr

## Host galaxies of

*Bloom et al. 1998,1999*
*Fruchter et al. 1999*

- z = 0.966

**GRB hosts**

- Long GRBs

## GRB and Core Collapse SNe hosts observed with Hubble Space Telescope

*Fruchter et al.2006*

- CC-SNe from Hubble High-z SN
- Search + HST GOODS

- GRBs

- Morphologies are significantly different:
- May metallicity explain the difference?

## Summary

- The detection of early optical counterparts indicates diversity in the multiwavelength
- phenomenolgy.   It is important to establish the conditions which determine the
- dominance of a given emission component over others in various GRBs
- From well resolved early afterglow light curves it is possible to measure fundamental
- Physical parameters (e.g., bulk Lorentz factor)
- Early spectroscopy reveals important details on the physics and geometry of
- intervening absorbers
- Short GRB afterglows are similar to those of long GRBs, but exhibit no signs of
- Underlying SNe.
- While short GRBs hosts exhibit wide variety of morphologies, the hosts of long
- GRBs are all late type and star-forming.  However, their morphologies,
- Sizes and luminosities are different form those of core-collapse SNe:  need to
- e_xplore possible selection effects_

## GRB050904 (z = 6.29)

- (TAROT)

*Boer et al. 2006*
*Watson et al. 2006*
*Cusumano et al. 2006*

**GRB050904 (z = 6.29)**

## z = 6.29

*Haislip et al. 2005*

**8 hours**

**3 days**

**GRB970228: first detection of X-ray and optical afterglow**

- 6 months
- later

***Costa et al. 1997***

***Van Paradijs et al. 1997***

**Notes:**
Historical slide

## Redshift 

- Redshift
- Measurement
*Djorgovski et al. 1999*

## “Firecone” model: relativistic shocks in a jet

**“****Firecone” model: relativistic shocks in a jet**

- ~ 100

- ~ 10

## Slide 22

## Isotropic irradiated –ray energy vs redshift

- z = 6.29

**Isotropic irradiated ********–ray energy vs redshift**

## Isotropic irradiated –ray energy vs redshift

**XRF060218**

**Isotropic irradiated ********–ray energy vs redshift**

## SHORT GRBs

- _SHORT GRBs_
- GRB050509b (z = 0.22)
- Upper limits on optical
- Flux are inconsistent
- With supernova
*Hjorth et al. 2005*

## GRB990123

*Maiorano et al. 2004 *

**GRB990123**

*Corsi et al. 2004*

- WFC

- PDS

- MECS

- 2-10 keV
- 15-28 keV

**optical flash**

## GRB050509b (z = 0.22)

**GRB050509b (z = 0.22)**

*Bloom et al. 2005*

- Host galaxy

## Optical afterglow of the short GRB050724 (T = 0.25 s)

*Berger et al. 2005*

## Colors of host  

- galaxies are
- very blue
- (compare, e.g.,
- with Hubble
- Deep Field)
*Fruchter et al. 1999*

**GRB hosts**

## z = 0.8

**z = 0.8**

**GRB990123 **
**(z = 1.6)**
**V ~ 23.5**

**GRB020405 **
**   ****(z = 0.7)**

**GRB990510 (z = 1.6)**
**V(host) = 28.5 !**

**z = 0.7**

**z = 0.8**

## Short GRB060313 

*Roming et al. 2006*

- Short GRB060313
- First UV detection
- Of short GRB
- z < 1.7

## GRB and Core Collapse SNe hosts observed with Hubble Space Telescope

*Fruchter et al.2006*

- CC-SNe from Hubble High-z SN
- Search + HST GOODS

- GRBs

- Morphologies are significantly different:
- May metallicity explain the difference?

- The difference may only be due to a selection
- effect: see type II SN2006at, detected during
- asteroid search (P. Brown’s talk)