Examinando por Autor "Savaglio, S."
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Ítem Identifying the host galaxy of the short GRB 100628A(EDP Sciences, 2015-11) Nicuesa Guelbenzu, A.; Klose, S.; Palazzi, E.; Greiner, J.; Michałowski, M.J.; Kann, D.A.; Hunt, L.K.; Malesani, D.; Rossi, A.; Savaglio, S.; Schulze, S.; Xu, D.; Afonso, P.M.J.; Elliott, J.; Ferrero, P.; Filgas, R.; Hartmann, D.H.; Krühler, T.; Knust, F.; Masetti, N.; Olivares, E. F.; Rau, A.; Schady, P.; Schmidl, S.; Tanga, M.; Updike, A.C.; Varela, K.We report on the results of a comprehensive observing campaign to reveal the host galaxy of the short GRB 100628A. This burst was followed by a faint X-ray afterglow but no optical counterpart was discovered. However, inside the X-ray error circle a potential host galaxy at a redshift of z = 0.102 was soon reported in the literature. If this system is the host, then GRB 100628A was the cosmologically most nearby unambiguous short burst with a measured redshift so far. We used the multi-colour imager GROND at the ESO/La Silla MPG 2.2 m telescope, ESO/VLT spectroscopy, and deep Australia Telescope Compact Array (ATCA) radio-continuum observations together with publicly available Gemini imaging data to study the putative host and the galaxies in the field of GRB 100628A. We confirm that inside the X-ray error circle the most probable host-galaxy candidate is the morphologically disturbed, interacting galaxy system at z = 0.102. The interacting galaxies are connected by a several kpc long tidal stream, which our VLT/FORS2 spectroscopy reveals strong emission lines of [O ii], [O iii], Hα and Hβ, characteristic for the class of extreme emission-line galaxies and indicative of ongoing star formation. The latter leaves open the possibility that the GRB progenitor was a member of a young stellar population. However, we indentify a second host-galaxy candidate slightly outside the X-ray error circle. It is a radio-bright, luminous elliptical galaxy at a redshift z = 0.311. With a K-band luminosity of 2 × 1011L this galaxy resembles the probable giant elliptical host of the first well-localized short burst, GRB 050509B. If this is the host, then the progenitor of GRB 100628A was a member of an old stellar population. © ESO, 2015.Ítem Multiwavelength analysis of three supernovae associated with gamma-ray bursts observed by GROND(EDP Sciences, 2015-05) Olivares, E.F.; Greiner, J.; Schady, P.; Klose, S.; Krühler, T.; Rau, A.; Savaglio, S.; Kann, D.A.; Pignata, G.; Elliott, J.; Rossi, A.; Nardini, M.; Afonso, P.M.J.; Filgas, R.; Nicuesa Guelbenzu, A.; Schmidl, S.; Sudilovsky, V.Context. After the discovery of the first connection between γ-ray bursts (GRBs) and supernovae (SNe) almost two decades ago, tens of SN-like rebrightenings have been discovered and about seven solid associations have been spectroscopically confirmed to date. Aims. We determine the luminosity, evolution, and origin of three SN rebrightenings in GRB afterglow light curves at z ∼ 0.5 along with accurate determinations of the host-galaxy extinction. We estimate physical parameters of the SN explosions, such as synthesised 56Ni mass, ejecta mass, and kinetic energy. Methods. We employ GROND optical/NIR data and Swift X-ray/UV data to estimate the host-galaxy extinction by modelling the afterglow spectral energy distribution, to determine the SN luminosity and evolution, and to construct quasi-bolometric light curves. The latter are corrected for the contribution of the NIR-bands using data available in the literature and black-body fits. We employ Arnett's analytic approach to obtain the physical parameters of the explosion. Results. The SNe 2008hw, 2009nz, and 2010ma observed by GROND exhibit 0.80, 1.15, and 1.78 times the optical (r′-band) luminosity of SN 1998bw, respectively. While SN 2009nz exhibits an evolution similar to SN 1998bw, SNe 2008hw and 2010ma show earlier peak times. The quasi-bolometric light curves (340-2200 nm) confirm the large luminosity of SN 2010ma (1.4 × 10 43 erg s-1), while SNe 2008hw and 2009nz reached a peak luminosity closer to that of SN 1998bw. The modelling indicates in 56 Ni masses of around 0.4-0.5 MO. Conclusions. By means of a very comprehensive data set, we found that the luminosity and the 56Ni mass of SNe 2008hw, 2009nz, and 2010ma resembles those of other known GRB-associated SNe. These findings strengthens previous claims of GRB-SNe being brighter than stripped-envelope SNe unaccompanied by GRBs. © ESO, 2015.Ítem The Peculiar Short-duration GRB 200826A and Its Supernova(Institute of Physics, 2022-06-01) Rossi, A.; Rothberg, B.; Palazzi, E.; Kann, D.A.; D'Avanzo, P.; Amati, L.; Klose, S.; Perego, A.; Pian, E.; Guidorzi, C.; Pozanenko, A.S.; Savaglio, S.; Stratta, G.; Agapito, G.; Covino, S.; Cusano, F.; D'Elia, V.; Pasquale, M. De; Valle, M. Della; Kuhn, O.; Izzo, L.; Loffredo, E.; Masetti, N.; Melandri, A.; Minaev, P.Y.; Guelbenzu, A. Nicuesa; Paris, D.; Paiano, S.; Plantet, C.; Rossi, F.; Salvaterra, R.; Schulze, S.; Veillet, C.; Volnova, A.A.Gamma-ray bursts (GRBs) are classified into long and short events. Long GRBs (LGRBs) are associated with the end states of very massive stars, while short GRBs (SGRBs) are linked to the merger of compact objects. GRB 200826A was a peculiar event, because by definition it was an SGRB, with a rest-frame duration of 1/40.5 s. However, this event was energetic and soft, which is consistent with LGRBs. The relatively low redshift (z = 0.7486) motivated a comprehensive, multiwavelength follow-up campaign to characterize its host, search for a possible associated supernova (SN), and thus understand the origin of this burst. To this aim we obtained a combination of deep near-infrared (NIR) and optical imaging together with spectroscopy. Our analysis reveals an optical and NIR bump in the light curve whose luminosity and evolution are in agreement with several SNe associated to LGRBs. Analysis of the prompt GRB shows that this event follows the E p,i-E iso relation found for LGRBs. The host galaxy is a low-mass star-forming galaxy, typical of LGRBs, but with one of the highest star formation rates, especially with respect to its mass ( logM∗/M⊙=8.6, SFR ∼4.0 M ⊙ yr-1). We conclude that GRB 200826A is a typical collapsar event in the low tail of the duration distribution of LGRBs. These findings support theoretical predictions that events produced by collapsars can be as short as 0.5 s in the host frame and further confirm that duration alone is not an efficient discriminator for the progenitor class of a GRB. © 2022. The Author(s). Published by the American Astronomical Society.Ítem The supernova of the MAGIC gamma-ray burst GRB 190114C(EDP Sciences, 2022-03) Melandri, A.; Izzo, L.; Pian, E.; Malesani, D.; Della Valle, M.; Rossi, A.; DAvanzo, P.; Guetta, D.; Mazzali, P.; Benetti, S.; Masetti, N.; Palazzi, E.; Savaglio, S.; Amati, L.; Antonelli, L.; Ashall, C.; Bernardini, M.; Campana, S.; Carini, R.; Covino, S.; DElia, V.; De Ugarte Postigo, A.; De Pasquale, M.; Filippenko, A.; Fruchter, A.; Fynbo, J.; Giunta, A.; Hartmann, D.; Jakobsson, P.; Japelj, J.; Jonker, P.; Kann, D.; Lamb, G.; Levan, A.; Martin-Carrillo, A.; Møller, P.; Piranomonte, S.; Pugliese, G.; Salvaterra, R.; Schulze, S.; Starling, R.; Stella, L.; Tagliaferri, G.; Tanvir, N.; Watson, D.We observed GRB 190114C (redshift z = 0.4245), the first gamma-ray burst (GRB) ever detected at TeV energies, at optical and near-infrared wavelengths with several ground-based telescopes and the Hubble Space Telescope, with the primary goal of studying its underlying supernova, SN 2019jrj. The monitoring spanned the time interval between 1.3 and 370 days after the burst, in the observer frame. We find that the afterglow emission can be modelled with a forward shock propagating in a uniform medium modified by time-variable extinction along the line of sight. A jet break could be present after 7 rest-frame days, and accordingly the maximum luminosity of the underlying supernova (SN) ranges between that of stripped-envelope core-collapse SNe of intermediate luminosity and that of the luminous GRB-associated SN 2013dx. The observed spectral absorption lines of SN 2019jrj are not as broad as in classical GRB SNe and are instead more similar to those of less-luminous core-collapse SNe. Taking the broad-lined stripped-envelope core-collapse SN 2004aw as an analogue, we tentatively derive the basic physical properties of SN 2019jrj. We discuss the possibility that a fraction of the TeV emission of this source might have had a hadronic origin and estimate the expected high-energy neutrino detection level with IceCube.