Swift observations of gamma-ray bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1119-1128 ◽  
Author(s):  
Neil Gehrels
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Gamma Ray Bursts ◽  
Optical Observations ◽  
Nearby Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Other Information ◽  
Short Grbs

Since its launch on 20 November 2004, the Swift mission has been detecting approximately 100 gamma-ray bursts (GRBs) each year, and immediately (within approx. 90 s) starting simultaneous X-ray and UV/optical observations of the afterglow. It has already collected an impressive database, including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows and a rapid follow-up by other observatories notified through the GCN. Advances in our understanding of short GRBs have been spectacular. The detection of X-ray afterglows has led to accurate localizations and the conclusion that short GRBs can occur in non-star-forming galaxies or regions, whereas long GRBs are strongly concentrated within the star-forming regions. This is consistent with the NS merger model. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at z ∼5–6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to a much greater distance than other techniques. The localization of GRB 060218 to a nearby galaxy, and the association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova.

SWIFT OBSERVATIONS OF GAMMA-RAY BURSTS

2008 ◽  
Vol 17 (09) ◽  
pp. 1311-1317
Author(s):  
NEIL GEHRELS
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Gamma Ray Bursts ◽  
Optical Observations ◽  
Nearby Galaxy ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Other Information

The Swift mission, launched on 20 November 2004, is detecting ~ 100 gamma-ray bursts (GRBs) each year, and immediately (within ~ 90 s) starting X-ray and UV/optical observations of the afterglow. It has already collected an impressive database including prompt emission to higher sensitivities than BATSE, uniform monitoring of afterglows, and rapid follow-up by other observatories notified through the Gamma-ray bursts Coordinates Network (GCN). The X-ray afterglows have been found to have complex temporal shapes including tails emission from the prompt phase and bright flares. X-ray and optical afterglow detections from short bursts have led to accurate localizations. It is found that they can occur in non-star forming galaxies or regions, whereas long GRBs are strongly concentrated within star forming regions. This is consistent with the NS merger model. Swift has greatly increased the redshift range of GRB detection. The highest redshift GRBs, at z ~ 5-6, are approaching the era of reionization. Ground-based deep optical spectroscopy of high redshift bursts is giving metallicity measurements and other information on the source environment to much greater distance than other techniques. The localization of GRB 060218 in a nearby galaxy, and association with SN 2006aj, added a valuable member to the class of GRBs with detected supernova. The prospects for future progress are excellent given the > 10 year orbital lifetime of the Swift satellite.

Delayed X-Ray Afterglows from Obscured Gamma-Ray Bursts in Star-forming Regions

2000 ◽  
Vol 543 (1) ◽  
pp. L35-L37 ◽  
Author(s):  
Peter Mészáros ◽  
Andrei Gruzinov
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions

scholarly journals Quark-Nova Explosion inside a Collapsar: Application to Gamma Ray Bursts

2009 ◽  
Vol 2009 ◽  
pp. 1-10 ◽  
Author(s):  
Rachid Ouyed ◽  
Denis Leahy ◽  
Jan Staff ◽  
Brian Niebergal
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
Stellar Envelope ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Long Duration ◽  
Model Features ◽  
Prompt Emission

If a quark-nova occurs inside a collapsar, the interaction between the quark-nova ejecta (relativistic iron-rich chunks) and the collapsar envelope leads to features indicative of those observed in Gamma Ray Bursts. The quark-nova ejecta collides with the stellar envelope creating an outward moving cap (Γ∼1–10) above the polar funnel. Prompt gamma-ray burst emission from internal shocks in relativistic jets (following accretion onto the quark star) becomes visible after the cap becomes optically thin. Model features include (i) precursor activity (optical, X-ray,γ-ray), (ii) promptγ-ray emission, and (iii) afterglow emission. We discuss SN-less long duration GRBs, short hard GRBs (including association and nonassociation with star forming regions), dark GRBs, the energetic X-ray flares detected in Swift GRBs, and the near-simultaneous optical andγ-ray prompt emission observed in GRBs in the context of our model.

scholarly journals X-shooter and ALMA spectroscopy of GRB 161023A

2018 ◽  
Vol 620 ◽  
pp. A119 ◽  
Author(s):  
A. de Ugarte Postigo ◽  
C. C. Thöne ◽  
J. Bolmer ◽  
S. Schulze ◽  
S. Martín ◽  
...  
Keyword(s):  
Near Infrared ◽  
Gamma Ray ◽  
High Redshift ◽  
Nir Spectroscopy ◽  
Host Galaxy ◽  
Star Forming ◽  
Star Forming Regions ◽  
Molecular Features ◽  
Short Period ◽  
Luminous Objects

Context. Long gamma-ray bursts (GRBs) are produced during the dramatic deaths of massive stars with very short lifetimes, meaning that they explode close to the birth place of their progenitors. Over a short period they become the most luminous objects observable in the Universe, being perfect beacons to study high-redshift star-forming regions. Aims. We aim to use the afterglow of GRB 161023A at a redshift z = 2.710 as a background source to study the environment of the explosion and the intervening systems along its line of sight. Methods. For the first time, we complement ultraviolet (UV), optical and near-infrared (NIR) spectroscopy with millimetre spectroscopy using the Atacama Large Millimeter Array (ALMA), which allows us to probe the molecular content of the host galaxy. The X-shooter spectrum shows a plethora of absorption features including fine-structure and metastable transitions of Fe, Ni, Si, C, and O. We present photometry ranging from 43 s to over 500 days after the burst. Results. We infer a host-galaxy metallicity of [Zn/H] = −1.11 ± 0.07, which, corrected for dust depletion, results in [X/H] = −0.94 ± 0.08. We do not detect molecular features in the ALMA data, but we derive limits on the molecular content of log(NCO/cm−2) < 15.7 and log(NHCO+/cm−-12, which are consistent with those that we obtain from the optical spectra, log(NH2/cm−2)< 15.2 and log(NCO/cm−2) < 14.5. Within the host galaxy, we detect three velocity systems through UV, optical and NIR absorption spectroscopy, all with levels that were excited by the GRB afterglow. We determine the distance from these systems to the GRB to be in the range between 0.7 and 1.0 kpc. The sight line to GRB 161023A shows nine independent intervening systems, most of them with multiple components. Conclusions. Although no molecular absorption was detected for GRB 161023A, we show that GRB millimetre spectroscopy is now feasible and is opening a new window on the study of molecular gas within star-forming galaxies at all redshifts. The most favoured lines of sight for this purpose will be those with high metallicity and dust.

Gamma-ray bursts and cosmology

2007 ◽  
Vol 365 (1854) ◽  
pp. 1363-1376 ◽  
Author(s):  
D.Q Lamb
Keyword(s):  
Dark Energy ◽  
Early Universe ◽  
Gamma Ray ◽  
High Redshift ◽  
Gamma Ray Bursts ◽  
Current Status ◽  
Scientific Results ◽  
Short Grbs ◽  
Very High

I review the current status of the use of gamma-ray bursts (GRBs) as probes of the early Universe and cosmology. I describe the promise of long GRBs as probes of the high redshift ( z >4) and very high redshift ( z >5) Universe, and several key scientific results that have come from observations made possible by accurate, rapid localizations of these bursts by Swift. I then estimate the fraction of long GRBs that lie at very high redshifts and discuss ways in which it may be possible to rapidly identify—and therefore study—a larger number of these bursts. Finally, I discuss the ways in which both long and short GRBs can be made ‘standard candles’ and used to constrain the properties of dark energy.

scholarly journals Gamma-ray Bursts

2005 ◽  
Vol 192 ◽  
pp. 459-466
Author(s):  
Alberto J. Castro-Tirado
Keyword(s):  
Gamma Ray ◽  
Massive Stars ◽  
Gamma Ray Bursts ◽  
Compact Objects ◽  
X Ray ◽  
Long Duration ◽  
Multi Wavelength ◽  
New Generation ◽  
Short Grbs

SummarySince their discovery in 1967 Gamma-ray bursts (GRBs) have been puzzling to astrophysicists. With the advent of a new generation of X–ray satellites in the late 90’s, it was possible to carry out deep multi-wavelength observations of the counterparts associated with the long duration GRBs class just within a few hours of occurrence, thanks to the observation of the fading X-ray emission that follows the more energetic gamma-ray photons once the GRB event has ended. The fact that this emission (the afterglow) extends at longer wavelengths, led to the discovery of optical/IR/radio counterparts in 1997-2003, greatly improving our understanding of these sources. The classical, long duration GRBs, have been observed to originate at cosmological distances in a range of redshifts with 0.1685 ≤ z ≤ 4.50 implying energy releases of ~ 1051 ergs. The recent results on GRB 021004 and GRB 030329 confirm that the central engines that power these extraordinary events are due to be collapse of massive stars rather than the merging of compact objects as previously also suggested. Short GRBs still remain a mystery as no counterparts have been detected so far.

Optical/UV afterglows: Swift UVOT overview

2007 ◽  
Vol 365 (1854) ◽  
pp. 1227-1234 ◽  
Author(s):  
Keith O Mason ◽  
Patricia Boyd ◽  
Mathew Page ◽  
Shashi Pandey ◽  
Pete Roming ◽  
...  
Keyword(s):  
Light Curve ◽  
Spectral Data ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Nearby Galaxy ◽  
Host Galaxies ◽  
Optical Telescope ◽  
X Ray ◽  
Diagnostic Power ◽  
Peculiar Case

The ultraviolet and optical telescope (UVOT) on Swift provides coverage of gamma-ray bursts and their afterglows in the 170–650 nm band, yielding multiwavelength data of considerable diagnostic power in conjunction with the Swift X-ray Telescope. The results from the first eighteen months of operation show a broad range of afterglow behaviour, with considerably more complexity in many bursts than would be expected from the simple fireball model for the explosion. We briefly illustrate the capabilities of UVOT for measuring the evolution of nearby supernovae by reference to the observations of GRB 060218, and discuss the peculiar case of GRB 060614, which apparently resides in a nearby galaxy but which did not show the expected supernova feature in its light curve due to radioactive nickel decay. We discuss how the combination of X-ray and UV/optical spectral data can be used to investigate the environment of GRB host galaxies.

scholarly journals The luminous host galaxy, faint supernova and rapid afterglow rebrightening of GRB 100418A

2018 ◽  
Vol 620 ◽  
pp. A190 ◽  
Author(s):  
A. de Ugarte Postigo ◽  
C. C. Thöne ◽  
K. Bensch ◽  
A. J. van der Horst ◽  
D. A. Kann ◽  
...  
Keyword(s):  
Light Curve ◽  
Gamma Ray ◽  
Formation Rate ◽  
Absolute Magnitude ◽  
Host Galaxy ◽  
Absorption And Emission ◽  
X Ray ◽  
Star Forming ◽  
Star Forming Regions ◽  
Central Engine

Context. Long gamma-ray bursts (GRBs) give us the chance to study both their extreme physics and the star-forming galaxies in which they form. Aims. GRB 100418A, at a redshift of z = 0.6239, had a bright optical and radio afterglow, and a luminous star-forming host galaxy. This allowed us to study the radiation of the explosion as well as the interstellar medium of the host both in absorption and emission. Methods. We collected photometric data from radio to X-ray wavelengths to study the evolution of the afterglow and the contribution of a possible supernova (SN) and three X-shooter spectra obtained during the first 60 h. Results. The light curve shows a very fast optical rebrightening, with an amplitude of ∼3 magnitudes, starting 2.4 h after the GRB onset. This cannot be explained by a standard external shock model and requires other contributions, such as late central-engine activity. Two weeks after the burst we detect an excess in the light curve consistent with a SN with peak absolute magnitude MV = −18.5 mag, among the faintest GRB-SNe detected to date. The host galaxy shows two components in emission, with velocities differing by 130 km s−1, but otherwise having similar properties. While some absorption and emission components coincide, the absorbing gas spans much higher velocities, indicating the presence of gas beyond the star-forming regions. The host has a star formation rate of SFR = 12.2 M⊙ yr−1, a metallicity of 12 + log(O/H) = 8.55, and a mass of 1.6 × 109 M⊙. Conclusions. GRB 100418A is a member of a class of afterglow light curves which show a steep rebrightening in the optical during the first day, which cannot be explained by traditional models. Its very faint associated SN shows that GRB-SNe can have a larger dispersion in luminosities than previously seen. Furthermore, we have obtained a complete view of the host of GRB 100418A owing to its spectrum, which contains a remarkable number of both emission and absorption lines.

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