THE AFTERGLOWS OF SWIFT-ERA GAMMA-RAY BURSTS. I. COMPARING PRE-SWIFT AND SWIFT-ERA LONG/SOFT (TYPE II) GRB OPTICAL AFTERGLOWS

Journal Article · Fri Sep 10 00:00:00 EDT 2010 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/720/2/1513· OSTI ID:21460037

Kann, D A; Klose, S; Schulze, S ^[1]; Zhang, B ^[2]; Malesani, D; Castro Ceron, J M ^[3]; Nakar, E ^[4]; Pozanenko, A; Burenin, R A ^[5]; Wilson, A C ^[6]; Butler, N R ^[7]; Jakobsson, P ^[8]; Andreev, M ^[9]; Antonelli, L A ^[10]; Bikmaev, I F ^[11]; Biryukov, V ^[12]; Boettcher, M ^[13]; Castro-Tirado, A J ^[14]; Chincarini, G ^[15]; Cobb, B E ^[16]

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1. Thueringer Landessternwarte Tautenburg, Sternwarte 5, D-07778 Tautenburg (Germany)
2. Department of Physics and Astronomy, University of Nevada, Las Vegas, NV 89154 (United States)
3. Dark Cosmology Centre, Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, DK-2100 Koebenhavn Oe (Denmark)
4. Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States)
5. Space Research Institute (IKI), 84/32 Profsoyuznaya Str, Moscow 117997 (Russian Federation)
6. Department of Astronomy, University of Texas, Austin, TX 78712 (United States)
7. Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450 (United States)
8. Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Herts, AL10 9AB (United Kingdom)
9. Terskol Branch of Institute of Astronomy of RAS, Kabardino-Balkaria Republic 361605 (Russian Federation)
10. INAF, Osservatorio Astronomico di Roma, via Frascati 33, 00040, Monteporzio Catone (Italy)
11. Kazan State University and Academy of Sciences of Tatarstan, Kazan (Russian Federation)
12. Crimean Laboratory of the Sternberg Astronomical Institute, Nauchny, Crimea 98409 (Ukraine)
13. Astrophysical Institute, Department of Physics and Astronomy, Clippinger 339, Ohio University, Athens, OH 45701 (United States)
14. Instituto de Astrofisica de AndalucIa (IAA-CSIC), Apartado de Correos, 3004, E-18080 Granada (Spain)
15. INAF, Osservatorio Astronomico di Brera, via E. Bianchi 46, 23807 Merate (Italy)
16. Department of Astronomy, Yale University, P.O. Box 208101, New Haven, CT 06520 (United States)

We have gathered optical photometry data from the literature on a large sample of Swift-era gamma-ray burst (GRB) afterglows including GRBs up to 2009 September, for a total of 76 GRBs, and present an additional three pre-Swift GRBs not included in an earlier sample. Furthermore, we publish 840 additional new photometry data points on a total of 42 GRB afterglows, including large data sets for GRBs 050319, 050408, 050802, 050820A, 050922C, 060418, 080413A, and 080810. We analyzed the light curves of all GRBs in the sample and derived spectral energy distributions for the sample with the best data quality, allowing us to estimate the host-galaxy extinction. We transformed the afterglow light curves into an extinction-corrected z = 1 system and compared their luminosities with a sample of pre-Swift afterglows. The results of a former study, which showed that GRB afterglows clustered and exhibited a bimodal distribution in luminosity space, are weakened by the larger sample. We found that the luminosity distribution of the two afterglow samples (Swift-era and pre-Swift) is very similar, and that a subsample for which we were not able to estimate the extinction, which is fainter than the main sample, can be explained by assuming a moderate amount of line-of-sight host extinction. We derived bolometric isotropic energies for all GRBs in our sample, and found only a tentative correlation between the prompt energy release and the optical afterglow luminosity at 1 day after the GRB in the z = 1 system. A comparative study of the optical luminosities of GRB afterglows with echelle spectra (which show a high number of foreground absorbing systems) and those without, reveals no indication that the former are statistically significantly more luminous. Furthermore, we propose the existence of an upper ceiling on afterglow luminosities and study the luminosity distribution at early times, which was not accessible before the advent of the Swift satellite. Most GRBs feature afterglows that are dominated by the forward shock from early times on. Finally, we present the first indications of a class of long GRBs, which form a bridge between the typical high-luminosity, high-redshift events and nearby low-luminosity events (which are also associated with spectroscopic supernovae) in terms of energetics and observed redshift distribution, indicating a continuous distribution overall.

• OSTI ID: 21460037
• Journal Information: Astrophysical Journal, Vol. 720, Issue 2; Other Information: DOI: 10.1088/0004-637X/720/2/1513; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
AFTERGLOW
BOLOMETERS
COSMIC GAMMA BURSTS
DUSTS
ENERGY SPECTRA
GALAXIES
LUMINOSITY
PHOTOMETRY
RED SHIFT
SUPERNOVAE
BINARY STARS
COSMIC RADIATION
ERUPTIVE VARIABLE STARS
IONIZING RADIATIONS
MEASURING INSTRUMENTS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
PRIMARY COSMIC RADIATION
RADIATIONS
SPECTRA
STARS
VARIABLE STARS