scholarly journals Gamma-ray bursts from dusty regions with little molecular gas

2015 ◽  
Vol 11 (A29B) ◽  
pp. 274-275
Author(s):  
Bunyo Hatsukade ◽  
Kouji Ohta ◽  
Akira Endo ◽  
Kouichiro Nakanishi ◽  
Yoichi Tamura ◽  
...  
Keyword(s):  
Milky Way ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Gas Emission ◽  
Nearby Star ◽  
Star Forming ◽  
First Case

AbstractWe detected CO line and 1.2-mm continuum emission from the two GRB host galaxies (GRB 020819B and GRB 051022) by using the Atacama Large Millimeter/submillimeter Array (ALMA). This is the first case for detecting molecular gas emission in GRB hosts. The ratio of molecular gas to dust mass of the GRB 020819B site is significantly lower than those of the Milky Way and nearby star-forming galaxies, suggesting that the star-forming environment where the GRB occur is different from those in local galaxies. The possible reason is that much of the dense gas is dissipated by a strong interstellar ultraviolet radiation field.

scholarly journals No supernovae detected in two long-duration gamma-ray bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1269-1275 ◽  
Author(s):  
D Watson ◽  
J.P.U Fynbo ◽  
C.C Thöne ◽  
J Sollerman
Keyword(s):  
Massive Star ◽  
Gamma Ray ◽  
Compact Star ◽  
Gamma Ray Bursts ◽  
Host Galaxy ◽  
Core Collapse ◽  
Host Galaxies ◽  
Star Forming ◽  
Long Duration ◽  
Spiral Arm

There is strong evidence that long-duration gamma-ray bursts (GRBs) are produced during the collapse of a massive star. In the standard version of the collapsar model, a broad-lined and luminous Type Ic core-collapse supernova (SN) accompanies the GRB. This association has been confirmed in observations of several nearby GRBs. Recent observations show that some long-duration GRBs are different. No SN emission accompanied the long-duration GRBs 060505 and 060614 down to limits fainter than any known Type Ic SN and hundreds of times fainter than the archetypal SN 1998bw that accompanied GRB 980425. Multi-band observations of the early afterglows, as well as spectroscopy of the host galaxies, exclude the possibility of significant dust obscuration. Furthermore, the bursts originated in star-forming galaxies, and in the case of GRB 060505, the burst was localized to a compact star-forming knot in a spiral arm of its host galaxy. We find that the properties of the host galaxies, the long duration of the bursts and, in the case of GRB 060505, the location of the burst within its host, all imply a massive stellar origin. The absence of an SN to such deep limits therefore suggests a new phenomenological type of massive stellar death.

scholarly journals Lyman continuum leakage in faint star-forming galaxies at redshift z = 3−3.5 probed by gamma-ray bursts

2020 ◽  
Vol 641 ◽  
pp. A30
Author(s):  
J.-B. Vielfaure ◽  
S. D. Vergani ◽  
J. Japelj ◽  
J. P. U. Fynbo ◽  
M. Gronke ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Formation Rate ◽  
Gamma Ray Bursts ◽  
Host Galaxy ◽  
Host Galaxies ◽  
Faint Star ◽  
Star Forming ◽  
Link Type ◽  
Lyman Continuum

Context. The identification of the sources that reionized the Universe and their specific contribution to this process are key missing pieces of our knowledge of the early Universe. Faint star-forming galaxies may be the main contributors to the ionizing photon budget during the epoch of reionization, but their escaping photons cannot be detected directly due to inter-galactic medium opacity. Hence, it is essential to characterize the properties of faint galaxies with significant Lyman continuum (LyC) photon leakage up to z ∼ 4 to define indirect indicators allowing analogs to be found at the highest redshift. Aims. Long gamma-ray bursts (LGRBs) typically explode in star-forming regions of faint, star-forming galaxies. Through LGRB afterglow spectroscopy it is possible to detect directly LyC photons. Our aim is to use LGRBs as tools to study LyC leakage from faint, star-forming galaxies at high redshift. Methods. Here we present the observations of LyC emission in the afterglow spectra of GRB 191004B at z = 3.5055, together with those of the other two previously known LyC-leaking LGRB host galaxies (GRB 050908 at z = 3.3467, and GRB 060607A at z = 3.0749), to determine their LyC escape fraction and compare their properties. Results. From the afterglow spectrum of GRB 191004B we determine a neutral hydrogen column density at the LGRB redshift of log(NH I/cm−2) = 17.2 ± 0.15, and negligible extinction (AV = 0.03 ± 0.02 mag). The only metal absorption lines detected are C IV and Si IV. In contrast to GRB 050908 and GRB 060607A, the host galaxy of GRB 191004B displays significant Lyman-alpha (Lyα) emission. From its Lyα emission and the non-detection of Balmer emission lines we constrain its star-formation rate (SFR) to 1 ≤ SFR ≤ 4.7 M⊙ yr−1. We fit the Lyα emission with a shell model and find parameters values consistent with the observed ones. The absolute (relative) LyC escape fractions we find for GRB 191004B, GRB 050908 and GRB 060607A are of 0.35−0.11+0.10 (0.43−0.13+0.12), 0.08−0.04+0.05 (0.08−0.04+0.05) and 0.20−0.05+0.05 (0.45−0.15+0.15), respectively. We compare the LyC escape fraction of LGRBs to the values of other LyC emitters found from the literature, showing that LGRB afterglows can be powerful tools to study LyC escape for faint high-redshift star-forming galaxies. Indeed we could push LyC leakage studies to much higher absolute magnitudes. The host galaxies of the three LGRBs presented here have all M1600 >  −19.5 mag, with the GRB 060607A host at M1600 >  −16 mag. LGRB hosts may therefore be particularly suitable for exploring the ionizing escape fraction in galaxies that are too faint or distant for conventional techniques. Furthermore, the time involved is minimal compared to galaxy studies.

scholarly journals Cosmic Gamma-Ray Bursts: The Big Picture

2005 ◽  
Vol 192 ◽  
pp. 433-439
Author(s):  
Kevin Hurley
Keyword(s):  
Magnetic Field ◽  
Gamma Rays ◽  
Massive Star ◽  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
X Rays ◽  
Host Galaxies ◽  
Star Forming ◽  
Open Questions ◽  
Big Picture

SummaryA “typical” GRB occurs in a star-forming region of a galaxy at a redshift z~1. In currently popular models, it is caused by the collapse of a massive star which has exhausted its nuclear fuel supply. The star collapses to a black hole threaded by a strong magnetic field, and possibly fed by an accretion torus. Through a variety of processes, electrons are accelerated and gamma-rays, X-rays, optical light, and radio emission ensue, with durations from seconds to years. In this talk, I will review the general observational properties of bursts, their afterglows and host galaxies, and some of the open questions about them.

scholarly journals Molecular gas masses of gamma-ray burst host galaxies

2018 ◽  
Vol 617 ◽  
pp. A143 ◽  
Author(s):  
Michał J. Michałowski ◽  
A. Karska ◽  
J. R. Rizzo ◽  
M. Baes ◽  
A. J. Castro-Tirado ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Statistical Significance ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Star Forming ◽  
Kolmogorov Smirnov ◽  
Atomic Gas ◽  
Gas Accretion ◽  
Gas Properties

Context. Long gamma-ray bursts (GRBs) can potentially be used as a tool to study star formation and recent gas accretion onto galaxies. However, the information about gas properties of GRB hosts is scarce. In particular, very few carbon monoxide (CO) line detections of individual GRB hosts have been reported. It has also been suggested that GRB hosts have lower molecular gas masses than expected from their star formation rates (SFRs). Aims. The objectives of this paper are to analyse molecular gas properties of the first substantial sample of GRB hosts and test whether they are deficient in molecular gas. Methods. We obtained CO(2-1) observations of seven GRB hosts with the APEX and IRAM 30 m telescopes. We analysed these data together with all other hosts with previous CO observations. From these observations we calculated the molecular gas masses of these galaxies and compared them with the expected values based on their SFRs and metallicities. Reults. We obtained detections for 3 GRB hosts (980425, 080207, and 111005A) and upper limits for the remaining 4 (031203, 060505, 060814, and 100316D). In our entire sample of 12 CO-observed GRB hosts, 3 are clearly deficient in molecular gas, even taking into account their metallicity (980425, 060814, and 080517). Four others are close to the best-fit line for other star-forming galaxies on the SFR-MH2 plot (051022, 060505, 080207, and 100316D). One host is clearly molecule rich (111005A). Finally, the data for 4 GRB hosts are not deep enough to judge whether they are molecule deficient (000418, 030329, 031203, and 090423). The median value of the molecular gas depletion time, MH2/SFR, of GRB hosts is ∼0.3 dex below that of other star-forming galaxies, but this result has low statistical significance. A Kolmogorov–Smirnov test performed on MH2/SFR shows an only ∼2σ difference between GRB hosts and other galaxies. This difference can partly be explained by metallicity effects, since the significance decreases to ∼1σ for MH2/SFR versus metallicity. Conclusions. We found that any molecular gas deficiency of GRB hosts has low statistical significance and that it can be attributed to their lower metallicities; and thus the sample of GRB hosts has molecular properties that are consistent with those of other galaxies, and they can be treated as representative star-forming galaxies. However, the molecular gas deficiency can be strong for GRB hosts if they exhibit higher excitations and/or a lower CO-to-H2 conversion factor than we assume, which would lead to lower molecular gas masses than we derive. Given the concentration of atomic gas recently found close to GRB and supernova sites, indicating recent gas inflow, our results about the weak molecular deficiency imply that such an inflow does not enhance the SFRs significantly, or that atomic gas converts efficiently into the molecular phase, which fuels star formation. Only if the analysis of a larger GRB host sample reveals molecular deficiency (especially close to the GRB position) would this support the hypothesis of star formation that is directly fuelled by atomic gas.

scholarly journals Unveiling the fundamental properties of Gamma-Ray Burst host galaxies

2011 ◽  
Vol 7 (S279) ◽  
pp. 212-215
Author(s):  
Sandra Savaglio
Keyword(s):  
Gamma Ray ◽  
Mass Function ◽  
Host Galaxies ◽  
Nearby Star ◽  
Massive Galaxies ◽  
Star Forming ◽  
Fundamental Properties ◽  
Long Duration ◽  
Solar Metallicity ◽  
Low Mass

AbstractThe galaxies hosting the most energetic explosions in the universe, the gamma-ray bursts (GRBs), are generally found to be low-mass, metal-poor, blue and star forming. However, the majority of the targets investigated so far (less than 100) are at relatively low redshift, z < 2. We know that at low redshift, the cosmic star formation is predominantly in small galaxies. Therefore, at low redshift, long-duration GRBs, which are associated with massive stars, are expected to be in small galaxies. Preliminary investigations of the stellar mass function of z < 1.5 GRB hosts does not indicate that these galaxies are different from the general population of nearby star-forming galaxies. At high-z, it is still unclear whether GRB hosts are different. Recent results indicate that a fraction of them might be in dusty regions of massive galaxies. Remarkable is the a super-solar metallicity measured in the interstellar medium of a z = 3.57 GRB host.

scholarly journals Reconciling the Metallicity Distributions of Gamma-ray Burst, Damped Lyman-α, and Lyman-break Galaxies atz≈ 3

2008 ◽  
Vol 4 (S254) ◽  
pp. 41-48
Author(s):  
Johan P. U. Fynbo ◽  
J. Xavier Prochaska ◽  
Jesper Sommer-Larsen ◽  
Miroslava Dessauges-Zavadsky ◽  
Palle Møller
Keyword(s):  
Simple Model ◽  
Cross Section ◽  
Gamma Ray ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Gamma Ray Bursts ◽  
Host Galaxies ◽  
Star Forming ◽  
Lyman Break Galaxies ◽  
Long Duration

AbstractWe test the hypothesis that the host galaxies of long-duration gamma-ray bursts (GRBs) as well as quasar-selected damped Lyman-α (DLA) systems are drawn from the population of UV-selected star-forming, highzgalaxies (generally referred to as Lyman-break galaxies). Specifically, we compare the metallicity distributions of the GRB and DLA populations against simple disk models where these galaxies are drawn randomly from the distribution of star-forming galaxies according to their star-formation rate and HI cross-section respectively. We find that it is possible to match both observational distributions assuming very simple and constrained relations between luminosity, metallicity, metallicity gradients and HI sizes. The simple model can be tested by observing the luminosity distribution of GRB host galaxies and by measuring the luminosity and impact parameters of DLA selected galaxies as a function of metallicity. Our results support the expectation that GRB and DLA samples, in contrast with magnitude limited surveys, provide an almost complete census of star-forming galaxies atz≈ 3.

scholarly journals Are long gamma-ray bursts biased tracers of star formation? Clues from the host galaxies of the Swift/BAT6 complete sample of bright LGRBs

2019 ◽  
Vol 623 ◽  
pp. A26 ◽  
Author(s):  
J. T. Palmerio ◽  
S. D. Vergani ◽  
R. Salvaterra ◽  
R. L. Sanders ◽  
J. Japelj ◽  
...  
Keyword(s):  
Star Formation ◽  
Gamma Ray ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Gamma Ray Bursts ◽  
High Mass ◽  
Close Binary ◽  
Host Galaxies ◽  
Star Forming ◽  
High Metallicity

Aims. Long gamma-ray bursts (LGRB) have been proposed as promising tracers of star formation owing to their association with the core-collapse of massive stars. Nonetheless, previous studies we carried out at z <  1 support the hypothesis that the conditions necessary for the progenitor star to produce an LGRB (e.g. low metallicity), were challenging the use of LGRBs as star-formation tracers, at least at low redshift. The goal of this work is to characterise the population of host galaxies of LGRBs at 1 < z < 2, investigate the conditions in which LGRBs form at these redshifts and assess their use as tracers of star formation. Methods. We performed a spectro-photometric analysis to determine the stellar mass, star formation rate, specific star formation rate and metallicity of the complete, unbiased host galaxy sample of the Swift/BAT6 LGRB sample at 1 < z < 2. We compared the distribution of these properties to the ones of typical star-forming galaxies from the MOSDEF and COSMOS2015 Ultra Deep surveys, within the same redshift range. Results. We find that, similarly to z <  1, LGRBs do not directly trace star formation at 1 < z < 2, and they tend to avoid high-mass, high-metallicity host galaxies. We also find evidence for an enhanced fraction of starbursts among the LGRB host sample with respect to the star-forming population of galaxies. Nonetheless we demonstrate that the driving factor ruling the LGRB efficiency is metallicity. The LGRB host distributions can be reconciled with the ones expected from galaxy surveys by imposing a metallicity upper limit of logOH ∼ 8.55. We can determine upper limits on the fraction of super-solar metallicity LGRB host galaxies of ∼20%, 10% at z <  1, 1 <  z <  2, respectively. Conclusions. Metallicity rules the LGRB production efficiency, which is stifled at Z ≳ 0.7 Z⊙. Under this hypothesis we can expect LGRBs to trace star formation at z >  3, once the bulk of the star forming galaxy population are characterised by metallicities below this limit. The role played by metallicity can be explained by the conditions necessary for the progenitor star to produce an LGRB. The moderately high metallicity threshold found is in agreement with the conditions necessary to rapidly produce a fast-rotating Wolf-Rayet stars in close binary systems, and could be accommodated by single star models under chemically homogeneous mixing with very rapid rotation and weak magnetic coupling.

scholarly journals ALMA CO Observations of the Host Galaxies of Long-duration Gamma-Ray Bursts. I. Molecular Gas Scaling Relations

2020 ◽  
Vol 892 (1) ◽  
pp. 42
Author(s):  
Bunyo Hatsukade ◽  
Kouji Ohta ◽  
Tetsuya Hashimoto ◽  
Kotaro Kohno ◽  
Kouichiro Nakanishi ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Scaling Relations ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Long Duration ◽  
Co Observations

scholarly journals Dust continuum, CO and  [Ci] 1-0 lines: Self-consistent H2 mass estimates and the possibility of globally CO-‘dark’ galaxies at z=0.35

2020 ◽  
Author(s):  
L Dunne ◽  
S J Maddox ◽  
C Vlahakis ◽  
H L Gomez
Keyword(s):  
Milky Way ◽  
Spectral Lines ◽  
Likelihood Method ◽  
Continuum Emission ◽  
Molecular Gas ◽  
Gas Reservoirs ◽  
Mean Values ◽  
Star Forming ◽  
The Mean ◽  
Very High

Abstract We present ALMA observations of a small but statistically complete sample of twelve 250μm selected galaxies at z = 0.35 designed to measure their dust submillimeter continuum emission as well as their  $\rm {^{12}CO(1-0)}$ and atomic carbon  [Ci](3P1-3P0) spectral lines. This is the first sample of galaxies with global measures of all three H2-mass tracers and which show star formation rates (4–26  $\rm M_{\odot }$ yr−1) and infra-red luminosities ($1-6\times 10^{11}\, {\,\rm L_{\odot }\,}$) typical of star forming galaxies in their era. We find a surprising diversity of morphology and kinematic structure; one-third of the sample have evidence for interaction with nearby smaller galaxies, several sources have disjoint dust and gas morphology. Moreover two galaxies have very high  $L^{\prime }_{\rm CI}$ / $L^{\prime }_{\rm {CO}}$ ratios for their global molecular gas reservoirs; if confirmed, such extreme intensity ratios in a sample of dust selected, massive star forming galaxies presents a challenge to our understanding of ISM. Finally, we use the emission of the three molecular gas tracers, to determine the carbon abundance,  $\rm {X_{CI}}$ , and CO–$\rm {H_2}$ conversion  αCO in our sample, using a weak prior that the gas-to-dust ratio is similar to that of the Milky Way for these massive and metal rich galaxies. Using a likelihood method which simultaneously uses all three gas tracer measurements, we find mean values and errors on the mean of $\langle {\,\alpha _{\rm {CO}}\,}\rangle =3.0\pm 0.5\, \rm {{\,\rm M_{\odot }\,}\, (K\, kms^{-1}\, pc^2)^{-1}}$ and $\langle {\,\rm {X_{CI}}\,}\rangle =1.6\pm 0.1\times 10^{-5}$ (or ${\,\alpha _{\rm {CI}}\,}=18.8\, {\,\rm {M_{\odot }\, (K\, kms^{-1}\, pc^2)^{-1}}\,}$) and ${\,\delta _{\rm {GDR}}\,}=128\pm 16$ (or ${\,\alpha _{\rm {850}}\,}=5.9\times 10^{12}\, \rm {W\, Hz^{-1}\, {\,\rm M_{\odot }\,}^{-1}}$), where our starting assumption is that these metal rich galaxies have an average gas-to-dust ratio similar to that of the Milky Way centered on ${\,\delta _{\rm {GDR}}\,}=135$.

scholarly journals Quenching by gas compression and consumption

2019 ◽  
Vol 624 ◽  
pp. A81 ◽  
Author(s):  
Allison W. S. Man ◽  
Matthew D. Lehnert ◽  
Joël D. R. Vernet ◽  
Carlos De Breuck ◽  
Theresa Falkendal
Keyword(s):  
Star Formation ◽  
Formation Rate ◽  
Relative Strength ◽  
Star Formation History ◽  
Molecular Gas ◽  
Host Galaxies ◽  
Massive Galaxies ◽  
Star Forming ◽  
Gas Compression ◽  
Formation History

The objective of this work is to study how active galactic nuclei (AGN) influence star formation in host galaxies. We present a detailed investigation of the star-formation history and conditions of a z = 2.57 massive radio galaxy based on VLT/X-shooter and ALMA observations. The deep rest-frame ultraviolet spectrum contains photospheric absorption lines and wind features indicating the presence of OB-type stars. The most significantly detected photospheric features are used to characterize the recent star formation: neither instantaneous nor continuous star-formation history is consistent with the relative strength of the Si IIλ1485 and S Vλ1502 absorption. Rather, at least two bursts of star formation took place in the recent past, at 6+1-2 Myr and ≳20 Myr ago, respectively. We deduce a molecular H2 gas mass of (3.9 ± 1.0) × 1010 M⊙ based on ALMA observations of the [C I] 3P2−3P1 emission. The molecular gas mass is only 13% of its stellar mass. Combined with its high star-formation rate of (1020-170+190 M⊙ yr-1, this implies a high star-formation efficiency of (26 ± 8) Gyr−1 and a short depletion time of (38 ± 12) Myr. We attribute the efficient star formation to compressive gas motions in order to explain the modest velocity dispersions (⩽55 km s−1) of the photospheric lines and of the star-forming gas traced by [C I]. Because of the likely very young age of the radio source, our findings suggest that vigorous star formation consumes much of the gas and works in concert with the AGN to remove any residual molecular gas, and eventually quenching star formation in massive galaxies.

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