Program: GN-2005B-Q-6
Title: | GRB North |
PI: | GRB Team |
Co-I(s): | |
Abstract
\\Probing DLAs and the ISM of High Redshift Galaxies with
Gamma-Ray Burst Afterglows//
Gamma-ray burst afterglows --- by virtue of their brightnesses,
featureless power-law spectra, location inside galaxies, and transient
nature --- provide a complementary tool to quasars in the study of the
chemical and dust content in high redshift galaxies. We propose a
spectroscopic study of nine (total of 24 hours) GRBs through the
Target of Opportunity program on both Gemini telescopes shortly after
($<1$ day) a GRB is localized from space. The primary objectives are
(1) to determine the metallicity, relative abundances and dust
extinction in the inner disks of GRB host galaxies for comparison with
quasar-probed extended galaxy halos, and (2) to study the absorption
and emission properties of foreground damped Lyman $\alpha$ (DLA)
galaxies discovered in Gemini spectroscopy of afterglows. The
proposed moderate-resolution GMOS spectroscopic observations of bright
afterglows---from the atmospheric cutoff to $\sim8000$
\AA---are designed to identify new DLAs and provide accurate
metal-line column density measurements of the kinematically-resolved
ISM of the host galaxies. GNIRSs observations will be especially
useful to precisely measure the redshift and study the ISM of the GRB
host for the highest $z$ and most dust extinguished bursts.
\\Probing the high redshift universe with GRBs//
Long-duration gamma-rays bursts are enormously luminous and hence potentially extremely important probes of the early universe. They act as beacons for absorption studies of the IGM and their own host galaxies during the era of reionization, and, being associated with the deaths of massive stars, trace global star formation at this early time. The launch of the Swift satellite, combined with a new generation of large-aperture ground-based robotic telescopes, provides the opportunity to systematically search for and study GRBs and their afterglows at very high redshifts from z~5 to z~20. In addition, our candidate selection may also reveal a population of highly reddened afterglows, hitherto rare amongst observed GRBs, which are likely to provide important clues to star formation in dense galactic environments. Gemini is crucial to this endeavour, providing the nIR spectroscopy from which we will determine redshifts and study the physical conditions along the line of sight.
\\Securing redshifts for a complete sample of Swift GRBs//
The new Gamma-Ray Burst (GRB) satellite Swift is now approaching full operations.
The nominal 2-year lifetime of Swift offers a unique chance to
build an objectively selected and complete sample of GRBs with measured
redshifts unlike the current very inhomogeneous set. This sample will give an
unbiased view of GRBs (energetics, luminosity function) and their environments
(host galaxies, link to star formation). Many redshifts for Swift bursts will
be measured with smaller telescopes, but for a small but crucial fraction an
8-m class telescope is necessary. We propose a programme to measure
redshifts from absorption lines in these afterglow spectra. GMOS will allow redshift
measurements for all GRBs to z~5.5. Very high-z GRBs and brighter
afterglows are the targets of other dedicated proposals.
This is a rapid response trigger proposal. We will trigger only on objects which do not have
redshifts at the time of our trigger and will make all data public within 48 hours of being taken.
\\Illuminating the Early Universe with Gamma Ray Bursts//
We propose Ultra Quick Response observations of up to six GRB afterglows in order to use these as tracers to measure the star formation rate out to z~7 and as lighthouses to study the evolution of metals and the environments of star formation over these redshifts. Following detection by the Swift satellite (now operational), candidate high-redshift afterglows will be identified from the absence of a V-band detection by Swift, which immediately means that the GRB is at z>>4. In these cases, we will trigger observations with GMOS on Gemini North using a large slit or the IFU covering the entire error circle, which will allow us to obtain a spectrum of the high-redshift GRB afterglow with a minimum of fuss.
\\What are the Short Duration Gamma-Ray Bursts?//
All our recent progress in understanding GRBs applies to the ``long-duration'' (t>2s) class,
for which long-lived afterglows have been found. The distinct, separate class of short-duration
GRBs remains enigmatic because their afterglows, if they exist at all, are clearly much fainter.
The recently launched Swift satellite should provide a higher rate of rapid, precise localisations
of short bursts than hitherto. We propose to continue our program of Gemini Quick Response observations
to conduct deep imaging searches for short-burst afterglows, with followup spectroscopy and photometry
of any that are found. Finding even a single event would therefore open up a new field of astrophysics.
Publications using this program's data
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[data]
[ADS] The Galaxy Hosts and Large-Scale Environments of Short-Hard Gamma-Ray Bursts
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[data]
[ADS] On the Incidence of Strong Mg II Absorbers along Gamma-Ray Burst Sight Lines
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[data]
[ADS] The Afterglow, Energetics, and Host Galaxy of the Short-Hard Gamma-Ray Burst 051221a
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[data]
[ADS] On the Absence of Wind Signatures in GRB Afterglow Spectra: Constraints on the Wolf-Rayet Winds of GRB Progenitors
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[data]
[ADS] A New Population of High-Redshift Short-Duration Gamma-Ray Bursts
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[data]
[ADS] Galaxy counterparts of intervening high-z sub-DLAs/DLAs and Mg ii absorbers towards gamma-ray bursts
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[data]
[ADS] An Independent Measurement of the Incidence of Mg II Absorbers along Gamma-Ray Burst Sight Lines: The End of the Mystery?
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[data]
[ADS] Unveiling the Secrets of Metallicity and Massive Star Formation Using DLAs along Gamma-Ray Bursts
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[data]
[ADS] The Offset and Host Light Distributions of Long Gamma-Ray Bursts: A New View From HST Observations of Swift Bursts