GRB 041219A is one of the longest and brightest gamma-ray bursts (GRBs) ever observed. It was discovered by the INTEGRAL satellite, and thanks to a precursor happening about 300 s before the bulk of the burst, ground-based telescopes were able to catch the rarely observed prompt emission in the optical and in the near-infrared bands. Here we present the detailed analysis of its prompt gamma-ray emission, as observed with IBIS onboard INTEGRAL, and of the available X-ray afterglow data collected by X-Ray Telescope onboard Swift. We then present the late-time multiband near-infrared imaging data, collected at the Telescopio Nazionale Galileo (TNG) and the Canada–France–Hawaii Telescope (CFHT), that allowed us to identify the host galaxy of the GRB as an underluminous, irregular galaxy of ∼5 × 109 M⊙ at best-fitting redshift of z= 0.31+0.54−0.26. We model the broad-band prompt optical to gamma-ray emission of GRB 041219A within the internal shock model. We were able to reproduce the spectra and light curve invoking the synchrotron emission of relativistic electrons accelerated by a series of propagating shock waves inside a relativistic outflow. On the other hand, it is less easy to simultaneously reproduce the temporal and spectral properties of the infrared data.

Based on observations with INTEGRAL, an ESA project with instruments and science data centre funded by ESA member states (especially the PI countries: Denmark; France; Germany; Italy; Switzerland and Spain), Czech Republic and Poland, and with the participation of Russia and the USA, and on observations obtained with WIRCam, a joint project of CFHT, Taiwan, Korea, Canada, France, at the CFHT which is operated by the National Research Council (NRC) of Canada, the Institute National des Sciences de l’Univers of the Centre National de la Recherche Scientifique of France, and the University of Hawaii. ISGRI has been realized and maintained in flight by CEA-Saclay/IRFU with the support of CNES. DG, FD and RM acknowledge the French Space Agency (CNES) for financial support. RH is funded by the research foundation from ‘Capital Fund Management’. PE acknowledges financial support from the Autonomous Region of Sardinia through a research grant under the program PO Sardegna FSE 2007–2013, L.R. 7/2007 ‘Promoting scientific research and innovation technology in Sardinia’. AFS acknowledges support from the Spanish MICYNN projects AYA2006-14056 and Consolider-Ingenio 2007-32022, and from the Generalitat Valenciana project Prometeo 2008/132.

11 páginas, 9 figuras, 3 tablas.-- El Pdf del artículo es la version pre-print: arXiv:1103.3663v1.-- et al.

Peer reviewed