Context. As a result of their relation to massive stars, long-duration gamma-ray bursts (GRBs) allow the pinpointing of star formation in galaxies independent of redshift, dust obscuration, or galaxy ...mass/size, thus providing a unique tool to investigate star formation history over cosmic time. Aims. About half of the optical afterglows of long-duration GRBs are missed owing to dust extinction and are primarily located in the most massive GRB hosts. It is important to investigate the amount of obscured star formation in these GRB host galaxies to understand this bias. Methods. Radio emission of galaxies correlates with star formation, but does not suffer extinction as do the optical star formation estimators. We selected 11 GRB host galaxies with either large stellar mass or large UV-based and optical-based star formation rates (SFRs) and obtained radio observations of these with the Australia Telescope Compact Array and the Karl Jansky Very Large Array. Results. Despite intentionally selecting GRB hosts with expected high SFRs, we do not find any radio emission related to star formation in any of our targets. Our upper limit for GRB 100621A implies that the earlier reported radio detection was due to afterglow emission. We detect radio emission from the position of GRB 020819B, but argue that it is in large part, if not completely, due to afterglow contamination. Conclusions. Half of our sample has radio-derived SFR limits, which are only a factor 2–3 above the optically measured SFRs. This supports other recent studies that the majority of star formation in GRB hosts is not obscured by dust.
Full text
Available for:
FMFMET, NUK, UL, UM, UPUK
We report on the design and fabrication of a novel all-glass four-channel beam splitter based on a Kösters prism for use in space. The Kösters prism, which consists of three pairs of individual ...prisms, is used to separate an incoming telescope beam into four spectral channels (λ = 800–1700 nm) with the goal to obtain a multi-band photometry of cosmic sources in the optical/near-infrared bands. We performed optical design studies to evaluate the influence of geometrical tolerances of the six individual prisms on the image quality. A stray light analysis revealed the impact of the composition on the overall optical performance. Mechanical design studies benchmarked possible mounting strategies. We considered optical adhesives, soldering and clamping. The influence of the mechanical loads during a rocket launch as well as thermal loads at 140 K (the operation temperature of the optical element) were studied. We optimized the coating properties of the prisms by considering the results from the optical design study as well as the technological requirements for the direct bonding of the prisms. Bonding strategies to realize the prism pairs were developed and successfully tested. A demonstrator Kösters prism was manufactured and is ready to validate its optical performance.
Full text
Available for:
EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We present optical, near-infrared, and Spitzer IRAC and MIPS observations of the host galaxy of the dark Swift gamma-ray burst GRB 080207. The host is faint, with extremely red optical-infrared ...colors (R -- K = 6.3, 24 Delta *mm/R-band flux ~1000) making it an extremely red object (ERO) and a dust-obscured galaxy (DOG). The spectral energy distribution (SED) shows the clear signature of the 1.6 Delta *mm photometric 'bump,' typical of evolved stellar populations. We use this bump to establish the photometric redshift z phot as 2.2+0.2 -- 0.3, using a vast library of SED templates, including M 82. The star formation rate (SFR) inferred from the SED fitting is ~119 M yr--1, the stellar mass 3 X 1011 M , and AV extinction from 1 to 2 mag. The ERO and DOG nature of the host galaxy of the dark GRB 080207 may be emblematic of a distinct class of dark GRB hosts, with high SFRs, evolved and metal-rich stellar populations, and significant dust extinction within the host galaxy.
A new class of ultra-long-duration (more than 10,000 seconds) γ-ray bursts has recently been suggested. They may originate in the explosion of stars with much larger radii than those producing normal ...long-duration γ-ray bursts or in the tidal disruption of a star. No clear supernova has yet been associated with an ultra-long-duration γ-ray burst. Here we report that a supernova (SN 2011kl) was associated with the ultra-long-duration γ-ray burst GRB 111209A, at a redshift z of 0.677. This supernova is more than three times more luminous than type Ic supernovae associated with long-duration γ-ray bursts, and its spectrum is distinctly different. The slope of the continuum resembles those of super-luminous supernovae, but extends further down into the rest-frame ultraviolet implying a low metal content. The light curve evolves much more rapidly than those of super-luminous supernovae. This combination of high luminosity and low metal-line opacity cannot be reconciled with typical type Ic supernovae, but can be reproduced by a model where extra energy is injected by a strongly magnetized neutron star (a magnetar), which has also been proposed as the explanation for super-luminous supernovae.
Full text
Available for:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
The purported spiral host galaxy of GRB 020819B at z = 0.41 has been seminal in establishing our view of the diversity of long-duration gamma-ray burst environments: optical spectroscopy of ...this host provided evidence that GRBs can form even at high metallicities, while millimetric observations suggested that GRBs may preferentially form in regions with minimal molecular gas. We report new observations from VLT (MUSE and X-shooter) which demonstrate that the purported host is an unrelated foreground galaxy. The probable radio afterglow is coincident with a compact, highly star-forming, dusty galaxy at z = 1.9621. The revised redshift naturally explains the apparent nondetection of CO(3-2) line emission at the afterglow site from ALMA. There is no evidence that molecular gas properties in GRB host galaxies are unusual, and limited evidence that GRBs can form readily at super-Solar metallicity.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Abstract
High-redshift gamma-ray bursts (GRBs) are useful to probe the early Universe, but only a few candidates have been detected so far. Here, we report the optical and near-infrared observations ...of the afterglow of a relatively high-redshift event GRB 220101A, which was triggered on New Year’s Day of 2022, and therefore referred to as the “New Year’s burst.” With the optical spectra obtained by XL2.16/BFOSC and NOT/ALFOSC, we determine the redshift of the burst to be
z
= 4.615. We find that the optical afterglow of GRB 220101A is one of the most luminous ever detected. Based on our optical and near-infrared data, and combined with the X-ray observations, we perform a multiband fit with the Python package
afterglowpy
. The jet opening angle is constrained to ∼3.°4, which is consistent with the jet-break time at ∼0.7 day. We also determine the circumburst density of
n
0
= 0.15 cm
−3
and kinetic energy
E
K,iso
= 3.5 × 10
54
erg. In the prompt phase of the burst, we find a “mirror” feature in the lightcurve from 80 s to 120 s. The physical origin of such a mirror feature is unclear.
A new class of ultra-long-duration (more than 10,000 seconds) γ-ray bursts has recently been suggested (1-3). They may originate in the explosion of stars with much larger radii than those producing ...normal long-duration γ-ray bursts (3,4) or in the tidal disruption of a star (3). No clear supernova has yet been associated with an ultra-long-duration γ-ray burst. Here we report that a supernova (SN 2011kl) was associated with the ultra-long-duration γ-ray burst GRB 111209A, at a redshift z of 0.677. This supernova is more than three times more luminous than type Ic supernovae associated with long-duration γ-ray bursts (5-7), and its spectrum is distinctly different. The slope of the continuum resembles those of super-luminous supernovae (8,9), but extends further down into the rest-frame ultraviolet implying a low metal content. The light curve evolves much more rapidly than those of super-luminous supernovae. This combination of high luminosity and low metalline opacity cannot be reconciled with typical type Ic supernovae, but can be reproduced by a model where extra energy is injected by a strongly magnetized neutron star (a magnetar), which has also been proposed as the explanation for super-luminous supernovae (10).
Full text
Available for:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
A new class of ultra-long-duration (more than 10,000 seconds) γ-ray bursts has recently been suggested1-3. They may originate in the explosion of stars with much larger radii than those producing ...normal long-duration γ-ray bursts3,4 or in the tidal disruption of a star3. No clear supernova has yet been associated with an ultra-long-duration γ-ray burst. Here we report that a supernova (SN 2011kl) was associated with the ultra-long-duration γ-ray burst GRB 111209A, at a redshiftz of 0.677. This supernova is more than three times more luminous than type Ic supernovae associated with long-duration γ-ray bursts5-7, and its spectrum is distinctly different. The slope of the continuum resembles those of super-luminous supernovae8,9, but extends further down into the rest-frame ultraviolet implying a low metal content. The light curve evolves much more rapidly than those of super-luminous supernovae. This combination of high luminosity and low metalline opacity cannot be reconciled with typical type Ic supernovae, but can be reproduced by a model where extra energy is injected by a strongly magnetized neutron star (a magnetar), which has also been proposed as the explanation for super-luminous supernovae10.
Full text
Available for:
DOBA, IJS, IZUM, KILJ, KISLJ, NUK, PILJ, PNG, SAZU, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK
We have compiled a large sample of Swift-era photometric data on long (Type II) and short (Type I) GRB afterglows. We compare the luminosity and energetics of the different samples to each other and ...to the afterglows of the pre-Swift era. Here, we present the first results of these studies.
PDF
