Multi-wavelength observations of the GRB 080319B afterglow and the modeling constraints^*

¹ Aryabhatta Research Institute of Observational Sciences (ARIES), Manora Peak, Nainital, India, 263129, India e-mail: shashi@aries.res.in
² Instituto de Astrofísica de Andalucía (IAA-CSIC), Apartado de Correos, 3.004, 18.080 Granada, Spain
³ Astronomical Institute “Anton Pannekoek”, Kruislaan, 403, 1098SJ, Amsterdam, The Netherlands
⁴ European Southern Observatory, Casilla 19001, Santiago 19, Chile
⁵ Institute of Astronomy, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
⁶ Institut d'Astrophysique et de Geophysique, Université de Liège, Allée du 6 Août 17, Sart Tilman (Bât. B5C), Liège 1, Belgium
⁷ Special Astrophysical Observatory of RAS, Nizhnij Arkhyz, Karachai-Cherkessia, 369167 Russia
⁸ Institute de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint Martin d'Hères, France
⁹ Space Research Institute of RAS, Profsoyuznaya, 84/32, Moscow 117997, Russia
¹⁰ Astronomical Institute of Kharkov National University, 35 Sumskaya, Kharkov, 61022, Ukraine
¹¹ Ussuriisk Astrophysical observatory, Far East Branch of RAS, Ussuriisk Region, Gornotaejnoe, 692533, Russia
¹² Inter-University Center for Astronomy and Astrophysics (IUCAA), Pune, Ganeshkhind, Post-bag No. 4, India
¹³ Sternberg Astronomical Institute, Moscow State University, Universitetsky pr., 13, Moscow 119992, Russia
¹⁴ Instituto de Astrofísica de Canarias (IAC), Via Láctea s/n, 38205 La Laguna (Tenerife), Spain
¹⁵ Ulugh Beg Astronomical Institute, Tashkent 700052, Uzbekistan
¹⁶ Dept. of Physics & Astronomy, Seoul National University, 56-1 San, Shillim-dong, Kwanak-gu, Seoul, Korea
¹⁷ SRI Crimean Astrophysical Observatory, Nauchny, Crimea, 98409, Ukraine

Received: 11 October 2008
Accepted: 2 April 2009

Abstract

Context. We present observations of the GRB  080319B afterglow at optical, mm, and radio frequencies between a few hours and 67 days after the burst.

Aims. We attempt to understand the nature of this extraordinarily bright explosion based on the observed properties and its comparison with afterglow models.

Methods. Our observations and other published multiwavelength data were used to reconstruct the light curves and spectral energy distributions of the burst afterglow.

Results. Our results indicate that the observed features of the afterglow agrees equally well with the inter stellar matter and the stellar wind density profiles of the circumburst medium. In the case of both density profiles, the maximum synchrotron frequency is below optical value and the cooling break frequency is below X-rays, ~10⁴ s after the burst. The derived value of the Lorentz factor at the time of naked-eye brightness is also ~300 for a corresponding blast-wave size of ~10¹⁸ cm.

Conclusions. The numerical fit to the multiwavelength afterglow data constraints the values of physical parameters and the emission mechanism of the burst.