Issue |
A&A
Volume 377, Number 2, October II 2001
|
|
---|---|---|
Page(s) | 450 - 461 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20011158 | |
Published online | 15 October 2001 |
Colors and luminosities of the optical afterglows of the γ-ray bursts
1
Astronomical Institute, Academy of Sciences of the Czech Republic, 251 65 Ondřejov, Czech Republic
2
Istituto Tecnologie e Studio delle Radiazioni Extraterrestri, CNR, via Gobetti 101, 40129 Bologna, Italy
Corresponding author: V. Šimon, simon@asu.cas.cz
Received:
26
December
2000
Accepted:
16
August
2001
Results of the study of the color indices and luminosities of 17 optical
afterglows (OAs) of GRBs are presented. We show that the color variations
during the decline of OAs (except for GRB000131) are relatively small
during days and allow a comparison among them, even for
the less densely sampled OAs. The colors in the observer frame, corrected
for the Galactic reddening, concentrate at
,
,
. The color evolution of
the OAs is negligible although their brightness declines by several
magnitudes during the considered time interval. Such a strong concentration
of the color indices also suggests that the intrinsic reddening (inside
their host galaxies) must be quite similar and relatively small for all
these events. The absolute brightness of OAs in the observer frame,
corrected for the host galaxy, lies within
to -22.2
for
days. This spread of
is
not significantly influenced by the shifts of λ, caused by the
different redshift z of the respective OAs. The general decline rate of
the OA sample considered here seems to be independent of the absolute
optical brightness of the OA, measured at some
identical for
all OAs, and the light curves of all events are almost parallel, when
corrected for the redshift-induced time dilation.
Key words: gamma rays: bursts / radiation mechanisms: non-thermal / plasmas / ISM: jets and outflows / galaxies: ISM / galaxies: starburst
© ESO, 2001
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