| Issue |
A&A
Volume 374, Number 2, August I 2001
|
|
|---|---|---|
| Page(s) | 382 - 393 | |
| Section | Astrophysical processes | |
| DOI | https://doi.org/10.1051/0004-6361:20010740 | |
| Published online | 15 August 2001 | |
GRB010222: Afterglow emission from a rapidly decelerating shock*
1
Istituto Tecnologie e Studio delle Radiazioni Extraterrestri, CNR, Via Gobetti 101, 40129 Bologna, Italy
2
Osservatorio Astronomico di Trieste, Via G.B. Tiepolo 11, 34131 Trieste, Italy
3
Centro per l'Astronomia Infrarossa e lo Studio del Mezzo Interstellare, CNR, Largo E. Fermi 5, 50125 Florence, Italy
4
Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monteporzio Catone, Italy
5
Osservatorio Astronomico di Brera, via Bianchi 46, 23807 Merate, Italy
6
Dipartimento di Astronomia, Università di Bologna, Via Ranzani 1, 40127 Bologna, Italy
7
Osservatorio Astronomico di Bologna, Via Ranzani 1, 40127 Bologna, Italy
8
Instituto de Astrofísica de Canarias, C/ Vía Láctea s/n, 38200, La Laguna, Tenerife, Spain
9
Osservatorio Astronomico di Padova, Vicolo dell'Osservatorio 5, 35122 Padua, Italy
10
Dipartimento di Astronomia, Università di Padova, Vicolo dell'Osservatorio 5, 35122 Padua, Italy
11
Osservatorio Astronomico di Asiago, Via dell'Osservatorio 8, 36012, Asiago, Italy
12
Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Florence, Italy
13
Dipartimento di Fisica, Università di Ferrara, via Paradiso 12, 44100 Ferrara, Italy
14
Telescopio Nazionale Galileo, Roque de Los Muchachos Astronomical Observatory, PO Box 565, 38700 Santa Cruz de La Palma, Spain
15
Istituto di Fisica Cosmica ed Applicazioni all'Informatica, CNR, via ugo La Malfa 153, 90146 Palermo, Italy
16
Osservatorio Astronomico di Collurania-Teramo, Via Maggini, 64100 Teramo, Italy
Corresponding author: N. Masetti, masetti@tesre.bo.cnr.it
Received:
20
March
2001
Accepted:
2
May
2001
The GRB010222 optical and near-infrared (NIR) afterglow was
monitored at the TNG and other Italian telescopes starting ~1 day
after the high-energy prompt event. The BVR light curves, which are the
best sampled, are continuously steepening and can be described
by two power laws, 
, of indices
0.7 and 
1.3 before and after a break
occurring at about 0.5 days after the GRB start time, respectively.
This model accounts well also for the flux in the U, I and J bands,
which are less well monitored. The temporal break appears to be achromatic.
The two K-band points are not consistent with the above behaviour, and
rather suggest a constant trend.
A low-resolution optical spectrum has also been taken with TNG.
In the optical spectrum we found three absorption systems at different
redshifts (0.927, 1.155 and 1.475), the highest of which represents a
lower limit to, and probably coincides with, the redshift of the GRB.
The broad-band optical spectral energy distributions do not appear to
vary with time, consistently with the achromatic behaviour of the light
curves.
We compare our measurements with different afterglow evolution scenarios
and we find that they favor a transition from relativistic to
non-relativistic conditions in the shock propagation.
Key words: gamma rays: bursts / radiation mechanisms: non-thermal / line: identification / cosmology: observations
Based on observations collected at: the Italian Telescopio Nazionale Galileo (TNG), operated on the island of La Palma by the Centro Galileo Galilei of the CNAA (Consorzio Nazionale per l'Astronomia e l'Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias; the Asiago Astronomical Observatory, Italy; the Bologna Astronomical Observatory in Loiano, Italy; the Campo Imperatore Astronomical Observatory, Italy, and; TIRGO infrared observatory, Switzerland.
© ESO, 2001
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