REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination

E. Molinari; S. D. Vergani; D. Malesani; S. Covino; P. D'Avanzo; G. Chincarini; F. M. Zerbi; L. A. Antonelli; P. Conconi; V. Testa; G. Tosti; F. Vitali; F. D'Alessio; G. Malaspina; L. Nicastro; E. Palazzi; D. Guetta; S. Campana; P. Goldoni; N. Masetti; E. J. A. Meurs; A. Monfardini; L. Norci; E. Pian; S. Piranomonte; D. Rizzuto; M. Stefanon; L. Stella; G. Tagliaferri; P. A. Ward; G. Ihle; L. Gonzalez; A. Pizarro; P. Sinclaire; J. Valenzuela

doi:10.1051/0004-6361:20077388

REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination

E. Molinari, S. D. Vergani, D. Malesani, S. Covino, P. D'Avanzo, G. Chincarini, F. M. Zerbi, L. A. Antonelli, P. Conconi, V. Testa, G. Tosti, F. Vitali, F. D'Alessio, G. Malaspina, L. Nicastro, E. Palazzi, D. Guetta, S. Campana, P. Goldoni, N. MasettiE. J. A. Meurs, A. Monfardini, L. Norci, E. Pian, S. Piranomonte, D. Rizzuto, M. Stefanon, L. Stella, G. Tagliaferri, P. A. Ward, G. Ihle, L. Gonzalez, A. Pizarro, P. Sinclaire, J. Valenzuela

Research output: Contribution to journal › Article › peer-review

238 Scopus citations

Abstract

Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γ₀ We aim to provide a direct measure of Γ₀. Methods. The early-time afterglow light curve carries information about Γ₀, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB 060418 and GRB 060607 A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of R_dec ≈ 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be R_dec ≈ 10¹⁷ cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB.

Original language	English
Pages (from-to)	L13-U16
Journal	Astronomy and Astrophysics
Volume	469
Issue number	1
DOIs	https://doi.org/10.1051/0004-6361:20077388
State	Published - Jul 2007
Externally published	Yes

Keywords

gamma rays : bursts
relativity

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10.1051/0004-6361:20077388

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Molinari, E., Vergani, S. D., Malesani, D., Covino, S., D'Avanzo, P., Chincarini, G., Zerbi, F. M., Antonelli, L. A., Conconi, P., Testa, V., Tosti, G., Vitali, F., D'Alessio, F., Malaspina, G., Nicastro, L., Palazzi, E., Guetta, D., Campana, S., Goldoni, P., ... Valenzuela, J. (2007). REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination. Astronomy and Astrophysics, 469(1), L13-U16. https://doi.org/10.1051/0004-6361:20077388

@article{320e6aea3fe9407a8b65060fc5d79a57,

title = "REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination",

abstract = "Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γ0 We aim to provide a direct measure of Γ0. Methods. The early-time afterglow light curve carries information about Γ0, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB 060418 and GRB 060607 A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of Rdec ≈ 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be Rdec ≈ 1017 cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB.",

keywords = "gamma rays : bursts, relativity",

author = "E. Molinari and Vergani, {S. D.} and D. Malesani and S. Covino and P. D'Avanzo and G. Chincarini and Zerbi, {F. M.} and Antonelli, {L. A.} and P. Conconi and V. Testa and G. Tosti and F. Vitali and F. D'Alessio and G. Malaspina and L. Nicastro and E. Palazzi and D. Guetta and S. Campana and P. Goldoni and N. Masetti and Meurs, {E. J. A.} and A. Monfardini and L. Norci and E. Pian and S. Piranomonte and D. Rizzuto and M. Stefanon and L. Stella and G. Tagliaferri and Ward, {P. A.} and G. Ihle and L. Gonzalez and A. Pizarro and P. Sinclaire and J. Valenzuela",

year = "2007",

month = jul,

doi = "10.1051/0004-6361:20077388",

language = "אנגלית",

volume = "469",

pages = "L13--U16",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

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number = "1",

}

Molinari, E, Vergani, SD, Malesani, D, Covino, S, D'Avanzo, P, Chincarini, G, Zerbi, FM, Antonelli, LA, Conconi, P, Testa, V, Tosti, G, Vitali, F, D'Alessio, F, Malaspina, G, Nicastro, L, Palazzi, E, Guetta, D, Campana, S, Goldoni, P, Masetti, N, Meurs, EJA, Monfardini, A, Norci, L, Pian, E, Piranomonte, S, Rizzuto, D, Stefanon, M, Stella, L, Tagliaferri, G, Ward, PA, Ihle, G, Gonzalez, L, Pizarro, A, Sinclaire, P & Valenzuela, J 2007, 'REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination', Astronomy and Astrophysics, vol. 469, no. 1, pp. L13-U16. https://doi.org/10.1051/0004-6361:20077388

REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination. / Molinari, E.; Vergani, S. D.; Malesani, D. et al.
In: Astronomy and Astrophysics, Vol. 469, No. 1, 07.2007, p. L13-U16.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination

T2 - The onset of the afterglow and the initial fireball Lorentz factor determination

AU - Molinari, E.

AU - Vergani, S. D.

AU - Malesani, D.

AU - Covino, S.

AU - D'Avanzo, P.

AU - Chincarini, G.

AU - Zerbi, F. M.

AU - Antonelli, L. A.

AU - Conconi, P.

AU - Testa, V.

AU - Tosti, G.

AU - Vitali, F.

AU - D'Alessio, F.

AU - Malaspina, G.

AU - Nicastro, L.

AU - Palazzi, E.

AU - Guetta, D.

AU - Campana, S.

AU - Goldoni, P.

AU - Masetti, N.

AU - Meurs, E. J. A.

AU - Monfardini, A.

AU - Norci, L.

AU - Pian, E.

AU - Piranomonte, S.

AU - Rizzuto, D.

AU - Stefanon, M.

AU - Stella, L.

AU - Tagliaferri, G.

AU - Ward, P. A.

AU - Ihle, G.

AU - Gonzalez, L.

AU - Pizarro, A.

AU - Sinclaire, P.

AU - Valenzuela, J.

PY - 2007/7

Y1 - 2007/7

N2 - Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γ0 We aim to provide a direct measure of Γ0. Methods. The early-time afterglow light curve carries information about Γ0, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB 060418 and GRB 060607 A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of Rdec ≈ 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be Rdec ≈ 1017 cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB.

AB - Context. Gamma-ray burst (GRB) emission is believed to originate in highly relativistic fireballs. Aims. Currently, only lower limits were securely set to the initial fireball Lorentz factor Γ0 We aim to provide a direct measure of Γ0. Methods. The early-time afterglow light curve carries information about Γ0, which determines the time of the afterglow peak. We have obtained early observations of the near-infrared afterglows of GRB 060418 and GRB 060607 A with the REM robotic telescope. Results. For both events, the afterglow peak could be clearly singled out, allowing a firm determination of the fireball Lorentz of Rdec ≈ 400, fully confirming the highly relativistic nature of GRB fireballs. The deceleration radius was inferred to be Rdec ≈ 1017 cm. This is much larger than the internal shocks radius (believed to power the prompt emission), thus providing further evidence for a different origin of the prompt and afterglow stages of the GRB.

KW - gamma rays : bursts

KW - relativity

UR - http://www.scopus.com/inward/record.url?scp=34250851929&partnerID=8YFLogxK

U2 - 10.1051/0004-6361:20077388

DO - 10.1051/0004-6361:20077388

M3 - ???researchoutput.researchoutputtypes.contributiontojournal.article???

SN - 0004-6361

VL - 469

SP - L13-U16

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

IS - 1

ER -

Molinari E, Vergani SD, Malesani D, Covino S, D'Avanzo P, Chincarini G et al. REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination. Astronomy and Astrophysics. 2007 Jul;469(1):L13-U16. doi: 10.1051/0004-6361:20077388

REM observations of GRB060418 and GRB060607A: the onset of the afterglow and the initial fireball Lorentz factor determination: The onset of the afterglow and the initial fireball Lorentz factor determination

Abstract

Keywords

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