TY - JOUR

T1 - A blast from the infant Universe

T2 - The very high-z GRB210905A

AU - Rossi, A.

AU - Frederiks, D. D.

AU - Kann, D. A.

AU - De Pasquale, M.

AU - Pian, E.

AU - Lamb, G.

AU - D'Avanzo, P.

AU - Izzo, L.

AU - Levan, A. J.

AU - Malesani, D. B.

AU - Melandri, A.

AU - Guelbenzu, A. Nicuesa

AU - Schulze, S.

AU - Strausbaugh, R.

AU - Tanvir, N. R.

AU - Amati, L.

AU - Campana, S.

AU - Cucchiara, A.

AU - Ghirlanda, G.

AU - Della Valle, M.

AU - Klose, S.

AU - Salvaterra, R.

AU - Starling, R. L. C.

AU - Stratta, G.

AU - Tsvetkova, A. E.

AU - Vergani, S. D.

AU - D'Ai, A.

AU - Burgarella, D.

AU - Covino, S.

AU - D'Elia, V.

AU - Postigo, A. de Ugarte

AU - Fausey, H.

AU - Fynbo, J. P. U.

AU - Frontera, F.

AU - Guidorzi, C.

AU - Heintz, K. E.

AU - Masetti, N.

AU - Maiorano, F.

AU - Mundell, C. G.

AU - Oates, S. R.

AU - Page, M. J.

AU - Palazzi, E.

AU - Palmerio, J.

AU - Pugliese, G.

AU - Rau, A.

AU - Saccardi, A.

AU - Sbarufatti, B.

AU - Svinkin, D. S.

AU - Tagliaferri, G.

AU - van der Horst, A. J.

AU - Watson, D. J.

AU - Ulanov, M.

AU - Wiersema, K.

AU - Xu, D.

AU - Zhang, J.

PY - 2022/9/21

Y1 - 2022/9/21

N2 - We present a detailed follow-up of the very energetic GRB210905A 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 E-iso = 1.27(-0.19)(+0.20) x 10(54) erg, GRB210905A lies in the top similar to 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 similar to 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 eta = 0.2, we derived a half-opening angle of 8.4 degrees +/- 1.0 degrees, which is the highest ever measured for a z greater than or similar to 6 burst, but within the range covered by closer events. The resulting collimation-corrected gamma-ray energy release of similar or equal to 1 x 10(52) 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 GRB210905A and its afterglow, we demonstrate that they are consistent within 2 sigma with those of less distant bursts, indicating that the powering mechanisms and progenitors do not evolve significantly with redshift.

AB - We present a detailed follow-up of the very energetic GRB210905A 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 E-iso = 1.27(-0.19)(+0.20) x 10(54) erg, GRB210905A lies in the top similar to 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 similar to 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 eta = 0.2, we derived a half-opening angle of 8.4 degrees +/- 1.0 degrees, which is the highest ever measured for a z greater than or similar to 6 burst, but within the range covered by closer events. The resulting collimation-corrected gamma-ray energy release of similar or equal to 1 x 10(52) 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 GRB210905A and its afterglow, we demonstrate that they are consistent within 2 sigma with those of less distant bursts, indicating that the powering mechanisms and progenitors do not evolve significantly with redshift.

KW - gamma-ray burst: general

KW - gamma-ray burst: individual: GRB210905A

KW - GAMMA-RAY BURST

KW - SWIFT/BAT6 COMPLETE SAMPLE

KW - AFTERGLOW LIGHT CURVES

KW - STAR-FORMATION CLUES

KW - JET OPENING ANGLE

KW - GRB HOST GALAXIES

KW - X-RAY

KW - OPTICAL FLASH

KW - PROMPT EMISSION

KW - POPULATION III

U2 - 10.1051/0004-6361/202243225

DO - 10.1051/0004-6361/202243225

M3 - Journal article

VL - 665

JO - Astronomy & Astrophysics

JF - Astronomy & Astrophysics

SN - 0004-6361

M1 - A125

ER -