scholarly journals Trigger Simulations for GRB Detection with the Swift Burst Alert Telescope

2011 ◽  
Vol 7 (S279) ◽  
pp. 347-348
Author(s):  
Amy Lien ◽  
Takanori Sakamoto ◽  
Neil Gehrels ◽  
David Palmer ◽  
Carlo Graziani
Keyword(s):  
Luminosity Function ◽  
Gamma Ray ◽  
Detection Threshold ◽  
Star Formation History ◽  
Precise Estimation ◽  
Formation History ◽  
Multi Wavelength ◽  
Systematic Biases ◽  
Trigger Algorithm ◽  
Burst Alert Telescope

AbstractUnderstanding the intrinsic cosmic long gamma-ray burst (GRB) rate is essential in many aspects of astrophysics and cosmology, such as revealing the connection between GRBs, supernovae (SNe), and stellar evolution. Swift, a multi-wavelength space telescope, is quickly expanding the GRB category by observing hundreds of GRBs and their redshifts. However, it remains difficult to determine the intrinsic GRB rate due to the complex trigger algorithm adopted by Swift. Current studies of the GRB rate usually approximate the Swift trigger algorithm by a single detection threshold. Nevertheless, unlike the previously flown GRB instruments, Swift has over 500 trigger criteria based on count rates and additional thresholds for localization. To investigate possible systematic biases and further explore the intrinsic GRB rate as a function of redshift and the GRB luminosity function, we adopt a Monte Carlo approach by simulating all trigger criteria used by Swift. A precise estimation of the intrinsic GRB rate is important to reveal the GRB origins and their relation to the black-hole forming SNe. Additionally, the GRB rate at high redshifts provides a strong probe of the star formation history in the early universe, which is hard to measure directly through other methods.

scholarly journals The Luminosity Function of White Dwarfs in the Local Disk and Halo

1989 ◽  
Vol 114 ◽  
pp. 15-23 ◽  
Author(s):  
James Liebert ◽  
Conard C. Dahn ◽  
David G. Monet
Keyword(s):  
White Dwarfs ◽  
Luminosity Function ◽  
Solar Neighborhood ◽  
Star Formation History ◽  
Empirical Estimates ◽  
Formation History ◽  
History Of ◽  
Cool White Dwarfs ◽  
Local Disk

The luminosity function (LF) and total space density of white dwarfs in the solar neighborhood contain important information about the star formation history of the stellar population, and provide an independent method of measuring its age. The first empirical estimates of the LF for degenerate stars were those of Weidemann (1967), Kovetz and Shaviv (1976) and Sion and Liebert (1977). The follow-up investigations made possible by the huge Luyten Palomar proper motion surveys, however, added many more faint white dwarfs to the known sample. While the number of known cool white dwarfs grew to nearly one hundred, these did not include any that were much fainter intrinsically than the coolest degenerates found from the early Luyten, van Biesbroeck and Eggen-Greenstein lists.

scholarly journals The 1.4-GHz cosmic star formation history at z < 1.3

2019 ◽  
Vol 36 ◽  
Author(s):  
James E. Upjohn ◽  
Michael J. I. Brown ◽  
Andrew M. Hopkins ◽  
Nicolas J. Bonne
Keyword(s):  
Star Formation ◽  
Luminosity Function ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Radio Continuum ◽  
Star Formation History ◽  
Star Forming ◽  
Formation History ◽  
Radio Measurements ◽  
Radio Luminosity Function

AbstractWe measure the cosmic star formation history out to z = 1.3 using a sample of 918 radio-selected star-forming galaxies within the 2-deg2 COSMOS field. To increase our sample size, we combine 1.4-GHz flux densities from the VLA-COSMOS catalogue with flux densities measured from the VLA-COSMOS radio continuum image at the positions of I &lt; 26.5 galaxies, enabling us to detect 1.4-GHz sources as faint as 40 μJy. We find that radio measurements of the cosmic star formation history are highly dependent on sample completeness and models used to extrapolate the faint end of the radio luminosity function. For our preferred model of the luminosity function, we find the star formation rate density increases from 0.017 M⊙ yr−1 Mpc−3 at z ∼ 0.225 to 0.092 M⊙ yr−1 Mpc−3 at z ∼ 1.1, which agrees to within 40% of recent UV, IR and 3-GHz measurements of the cosmic star formation history.

scholarly journals A Possible Detection of CO (J = 3–2) Emission From the Host Galaxy of GRB 980425 with Atacama Submillimeter Telescope Experiment

2006 ◽  
Vol 2 (S235) ◽  
pp. 312-312
Author(s):  
Bunyo Hatsukade ◽  
Kotaro Kohno ◽  
Akira Endo ◽  
Tomoka Tosaki ◽  
Kouji Ohta ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Line Emission ◽  
Emission Feature ◽  
Star Formation History ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Long Duration ◽  
The Galaxy ◽  
Multi Wavelength

AbstractLong-duration gamma-ray bursts (GRBs) are considered to be due to the death of massive stars. Therefore, GRBs are closely associated with the star formation of host galaxies. Since GRBs can be detected at cosmological distances, they are expected to be probes of the star formation history of the Universe. In order to determine the use of GRBs, it is essential to understand the star formation of their hosts. Multi-wavelength observations have shown that the star formation rates (SFRs) of GRB hosts derived from submillimeter/radio observations are generally higher than those from optical/UV observations (Berger et al. 2003). This implies that GRB hosts have a large amount of molecular gas and massive star formation obscured by dust. In order to solve this problem, it is necessary to derive the SFRs in a method which is independent of existing methods and not affected by dust extinction.We observed 12CO (J = 3–2) line emission from the host galaxy of GRB 980425 using the Atacama Submillimeter Telescope Experiment (ASTE). Five points were observed covering the entire region of the galaxy, and we find possible emission features (S/N ~ 3 σ) at the velocity range corresponding to the redshift of the galaxy. By combining all spectra of five points, we obtain a global spectrum with a ~4 σ emission feature. If the features are real, this is the first detection of CO among GRB hosts. We derive the total gas mass of M(H2)=7 ± 2× 108M⊙ assuming a CO-to-H2 conversion factor of αCO = 8.0M⊙ (K km s−1 pc2)−1, which is deduced using the correlation between the αCO and the metallicity. The dynamical mass is calculated to be Mdyn=2× 1010M⊙, and M(H2)/Mdyn~3% is consistent with those of nearby dwarfs and normal spirals. The derived SFR is 0.5 ± 0.1 M⊙ yr−1 based on the Schmidt law. This SFR agrees with the results of previous Hα observations, suggesting that there is no significant obscured star formation in this host galaxy. This result implies that there is a variety of GRB hosts in terms of the presence of obscured star formation.

scholarly journals Gamma-Ray Bursts and the Early Star-Formation History

2016 ◽  
Vol 202 (1-4) ◽  
pp. 181-194 ◽  
Author(s):  
R. Chary ◽  
P. Petitjean ◽  
B. Robertson ◽  
M. Trenti ◽  
E. Vangioni
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Star Formation History ◽  
Formation History

scholarly journals Gamma-Ray Bursts and the Early Star-Formation History

2016 ◽  
pp. 183-196
Author(s):  
R. Chary ◽  
P. Petitjean ◽  
B. Robertson ◽  
M. Trenti ◽  
E. Vangioni
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Star Formation History ◽  
Formation History

scholarly journals A gamma-ray determination of the Universe’s star formation history

Science ◽  
2018 ◽  
Vol 362 (6418) ◽  
pp. 1031-1034 ◽  
Author(s):  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Cosmic Time ◽  
Star Formation History ◽  
Large Area ◽  
Extragalactic Background Light ◽  
Galaxy Surveys ◽  
Formation History ◽  
History Of ◽  
The Universe

The light emitted by all galaxies over the history of the Universe produces the extragalactic background light (EBL) at ultraviolet, optical, and infrared wavelengths. The EBL is a source of opacity for gamma rays via photon-photon interactions, leaving an imprint in the spectra of distant gamma-ray sources. We measured this attenuation using 739 active galaxies and one gamma-ray burst detected by the Fermi Large Area Telescope. This allowed us to reconstruct the evolution of the EBL and determine the star formation history of the Universe over 90% of cosmic time. Our star formation history is consistent with independent measurements from galaxy surveys, peaking at redshiftz~ 2. Upper limits of the EBL at the epoch of reionization suggest a turnover in the abundance of faint galaxies atz~ 6.

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