Examinando por Autor "De Pasquale, M."

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    A blast from the infant universe: the very high- z GRB 210905A
    (EDP Sciences, 2022-09) Rossi, A.; Frederiks, D.D.; Kann, D.A.; De Pasquale, M.; Pian, E.; Lamb, G.; D'Avanzo, P.; Izzo, L.; Levan, A.J.; Malesani, D.B.; Melandri, A.; Nicuesa Guelbenzu, A.; Schulze, S.; Strausbaugh, R.; Tanvir, N.R.; Amati, L.; Campana, S.; Cucchiara, A.; Ghirlanda, G.; Della Valle, M.; Klose, S.; Salvaterra, R.; Starling, R.L.C.; Stratta, G.; Tsvetkova, A.E.; Vergani, S.D.; D'Aì, A.; Burgarella, D.; Covino, S.; D'Elia, V.; Postigo, A. De Ugarte; Fausey, H.; Fynbo, J.P.U.; Frontera, F.; Guidorzi, C.; Heintz, K.E.; Masetti, N.; Maiorano, E.; Mundell, C.G.; Oates, S.R.; Page, M.J.; Palazzi, E.; Palmerio, J.; Pugliese, G.; Rau, A.; Saccardi, A.; Sbarufatti, B.; Svinkin, D.S.; Tagliaferri, G.; Van Der Horst, A.J.; Watson, D.J.; Ulanov, M.V.; Wiersema, K.; Xu, D.; Zhang, J.
    We present a detailed follow-up of the very energetic GRB 210905A at a high redshift of z = 6.312 and its luminous X-ray and optical afterglow. Following the detection by Swift and Konus-Wind, we obtained a photometric and spectroscopic follow-up in the optical and near-infrared (NIR), covering both the prompt and afterglow emission from a few minutes up to 20 Ms after burst. With an isotropic gamma-ray energy release of Eiso = 1.27−0.19+0.20 × 1054 erg, GRB 210905A lies in the top ∼7% of gamma-ray bursts (GRBs) in the Konus-Wind catalogue in terms of energy released. Its afterglow is among the most luminous ever observed, and, in particular, it is one of the most luminous in the optical at t ≳ 0.5 d in the rest frame. The afterglow starts with a shallow evolution that can be explained by energy injection, and it is followed by a steeper decay, while the spectral energy distribution is in agreement with slow cooling in a constant-density environment within the standard fireball theory. A jet break at ∼46.2 ± 16.3 d (6.3 ± 2.2 d rest-frame) has been observed in the X-ray light curve; however, it is hidden in the H band due to a constant contribution from the host galaxy and potentially from a foreground intervening galaxy. In particular, the host galaxy is only the fourth GRB host at z > 6 known to date. By assuming a number density n = 1 cm−3 and an efficiency η = 0.2, we derived a half-opening angle of 8.4 ° ±1.0°, which is the highest ever measured for a z ≳ 6 burst, but within the range covered by closer events. The resulting collimation-corrected gamma-ray energy release of ≃1 × 1052 erg is also among the highest ever measured. The moderately large half-opening angle argues against recent claims of an inverse dependence of the half-opening angle on the redshift. The total jet energy is likely too large to be sustained by a standard magnetar, and it suggests that the central engine of this burst was a newly formed black hole. Despite the outstanding energetics and luminosity of both GRB 210905A and its afterglow, we demonstrate that they are consistent within 2σ with those of less distant bursts, indicating that the powering mechanisms and progenitors do not evolve significantly with redshift.
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    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.