# Presentation: 116040

## The redshift of XRF 030528

## X-ray Flashes - prompt

-  BeppoSAX WFC  (Heise et al. 2001)
-  similar to LGRBs except Epeak
-  HETE-2 observer frame classification:
-    log(Sx(2-30 keV) / S(30-400 keV)) (Sakamoto et al. 2004)

## X-ray Flashes - late

-  XRFs/XRRs/LGRBs  form continuum
-  X-ray, optical, radio afterglows
-  underlying supernova (Fynbo et al. 2003, Soderberg et al. 2005)
-  late type host galaxies (e.g. Bloom et al. 2003)

## X-ray Flashes - models

-  high baryon loading in the ejecta (e.g. Dermer et al. 1999)
-  low contrast between the bulk Lorentz factors of colliding
-   relativistic shells (Barraud et al. 2005)
-  off-axis bursts  (e.g. Yamazaki et al. 2002)
-  high redshift  (e.g. Heise et al. 2001)

**          ****Distance Scale is important:**
- XRF 020903:  z=0.251 (Soderberg et al. 2004)
- XRF 030429:  z=2.66 (Jakobsson et al. 2005)
- 011030 (<3.5); 020427 (<2.3); 030723 (<2.3);
- 040701 (0.2146 ??)

## GRB 030528

** ****T****90 ****= 49.1s (30-400 keV)**
** ****E****peak**** = 32±5 keV**
** ****log (S****X**** / S********) = 0.04**

**GRB 030528**

## Host Galaxy - Photometry

**V = 21.9 ± 0.2**
**R = 22.0 ± 0.2**
**I  = 21.3 ± 0.3**
**J  = 20.8 ± 0.1**
**H < 20.3 **
**K = 19.9 ± 0.7**

- SED consistent with late type galaxy at z<4

## VLT/FORS2 LSS (2 hrs 300V April/May05)

**VLT/FORS2 LSS **(2 hrs 300V April/May05)
** **

**(AR et al. 2005, A&A accepted)**

**z=0.782±0.001**

- sky

- host

## 030528 in the rest frame

- 030528: Epeak,obs        = 32±5 keV    Epeak,rest       = 57±9 keV
-               log(Sx/S)obs = 0.04           log(Sx/S)rest = -0.17

- 030528: Epeak,obs        = 32±5 keV    Epeak,rest       = 57±9 keV
-               log(Sx/S)obs = 0.04           log(Sx/S)rest = -0.17
- 	  XRFobs                              XRRrest

- 030528: Epeak,obs        = 32±5 keV    Epeak,rest       = 57±9 keV
-               log(Sx/S)obs = 0.04           log(Sx/S)rest = -0.17
- 	  XRFobs                              XRRrest
- 030429: XRFobs                              XRR/GRBrest
- 020903: XRFobs                              XRFrest

**030528 in the rest frame**

## Summary

-  z=0.782
-  observer frame XRF   rest frame XRR
-  rest frame classification scheme required
-  host properties (AR et al. 2005, A&A accepted)
-  Do we expect also short XRFs ?

## Slide 10

## Host Properties

-  metallicity from emission lines: R23=log(([OIII]+[OII])/H)
-    0.1<Z<0.6

|  | MAB [mag] | L/L* |
| --- | --- | --- |
| U | -20.5  0.1 | 1.2  0.2 |
| B | -20.7  0.1 | 0.5  0.1 |
| R | -21.1  0.1 | 0.35  0.05 |
| J | -21.4  0.1 | 0.25  0.05 |
| Ks | -21.6  0.1 | 0.17  0.05 |

-  metallicity from emission lines: R23=log(([OIII]+[OII])/H)
-    0.1<Z<0.6
-  absolute magnitudes

## Star Formation

|  |  | SFR | SSFR | SFR |
| --- | --- | --- | --- | --- |
|  |  | [Ms yr-1] | [Ms yr-1] | [Ms yr-1 Ms-1] |
| [OII] | K98 | 6  2 | 12  3 | 210-10 |
|  | RG02 | 37  4 | 74  6 | 1210-10 |
| UV | K98 | 4  1 | 8  2 | 110-10 |
|  | RG02 | 17  3 | 34  4 | 510-10 |

**Star Formation**

- [OII]: SFR(Ms yr-1) =  1.4  0.4  10-41L[OII]  (Kennicut 1998)
-           SFR(Ms yr-1) =  8.4  0.4  10-41L[OII]  (Rosa-Gonzalez 2002)

- [OII]: SFR(Ms yr-1) =  1.4  0.4  10-41L[OII]  (Kennicut 1998)
-           SFR(Ms yr-1) =  8.4  0.4  10-41L[OII]  (Rosa-Gonzalez 2002)
- UV:   SFR(Ms yr-1) =  1.4  0.4  10-28L,UV  (Kennicut 1998)
-           SFR(Ms yr-1) =  6.4  0.4  10-28L,UV  (Rosa-Gonzalez 2002)

## Energetics

**E****iso,******** = 2.0±0.7x10****52**** erg (2-400keV)**

**030528**

**Energetics**

**(Ghirlanda et al. 2004)**