- J. Elliott
- J. Greiner
- S. Khochfar
- P. Schady
- J. L. Johnson
- A. Rau
Original language | English |
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Pages (from-to) | 113 |
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Journal | Astronomy & Astrophysics |
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Volume | 539 |
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Publication status | Published - 1 Mar 2012 |
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Context. To answer questions on the start and duration of the epoch of
reionisation, periods of galaxy mergers and properties of other
cosmological encounters, the cosmic star formation history,
dotρ*} or CSFH, is of fundamental importance. Using the
association of long-duration gamma-ray bursts (LGRBs) with the death of
massive stars and their ultra-luminous nature
(>1052ergs-1), the CSFH can be probed to higher
redshifts than current conventional methods. Unfortunately, no consensus
has been reached on the manner in which the LGRB rate, dot{ρ_grb} or
LGRBR, traces the CSFH, leaving many of the questions mentioned mostly
unexplored by this method. Aims: Observations by the gamma-ray
burst near-infrared detector (GROND) over the past 4 years have, for the
first time, acquired highly complete LGRB samples. Driven by these
completeness levels and new evidence of LGRBs also occurring in more
massive and metal rich galaxies than previously thought, the possible
biases of the dot{ρ_grb}-dot{ρ*} connection are
investigated over a large range of galaxy properties. Methods:
The CSFH is modelled using empirical fits to the galaxy mass function
and galaxy star formation rates. Biasing the CSFH by means of
metallicity cuts, mass range boundaries, and other unknown redshift
dependencies of the form
dot{ρ_grbproptodot{ρ*(1+z)δ} (1 +
z)δ, a dot{ρ_grb} is generated and compared to the
highly complete GROND LGRB sample. Results: It is found that
there is no strong preference for a metallicity cut or fixed galaxy mass
boundaries and that there are no unknown redshift effects (δ = 0),
in contrast to previous work which suggest values of Z/Z⊙
0.1-0.3. From the best-fit models obtained, we predict that 1.2% of the
LGRB burst sample exists above z = 6. Conclusions: The linear
relationship between dot{ρ_grb} and dot{ρ*} suggested
by our results implies that redshift biases present in previous LGRB
samples significantly affect the inferred dependencies of LGRBs on their
host galaxy properties. Such biases can lead to, for example, an
interpretation of metallicity limitations and evolving LGRB luminosity
functions.
- gamma-ray burst: general, cosmology: miscellaneous
ID: 11175705