Publications (60)
The Afterglow and ULIRG Host Galaxy of the Dark Short GRB 120804A
E. Berger, B. A. Zauderer, A. Levan +12
We present the optical discovery and sub-arcsecond optical and X-ray localization of the afterglow of the short GRB 120804A, as well as optical, near-IR, and radio detections of it…
Eight Years of Light from ASASSN-15oi: Towards Understanding the Late-time Evolution of TDEs
A. Hajela, K. D. Alexander, R. Margutti +26
We present the results from an extensive follow-up campaign of the Tidal Disruption Event (TDE) ASASSN-15oi spanning d, offering an unprecedented window into t…
Evidence for X-ray Emission in Excess to the Jet Afterglow Decay 3.5 yrs After the Binary Neutron Star Merger GW 170817: A New Emission Component
A. Hajela, R. Margutti, J. S. Bright +34
For the first years after the binary neutron star merger event GW 170817 the radio and X-ray radiation has been dominated by emission from a structured relativistic off-axi…
GRB 120521C at z~6 and the Properties of High-redshift GRBs
T. Laskar, E. Berger, N. Tanvir +9
We present optical, near-infrared, and radio observations of the afterglow of GRB 120521C. By modeling the multi-wavelength dataset, we derive a photometric redshift of z~6.0, whic…
The Broad-band Counterpart of the Short GRB 200522A at : A Luminous Kilonova or a Collimated Outflow with a Reverse Shock?
W. Fong, T. Laskar, J. Rastinejad +20
We present the discovery of the radio afterglow and near-infrared (NIR) counterpart of the Swift short GRB 200522A, located at a small projected offset of kpc from the…
The ultra-long GRB 220627A at z=3.08
S. de Wet, L. Izzo, P. J. Groot +19
GRB 220627A is a rare burst with two distinct gamma-ray emission episodes separated by almost 1000 s that triggered the Fermi Gamma-ray Burst Monitor twice. High-energy GeV emissio…
GRB Fermi-LAT afterglows: explaining flares, breaks, and energetic photons
N. Fraija, T. Laskar, S. Dichiara +4
The Fermi-LAT collaboration presented the second gamma-ray burst (GRB) catalog covering its first 10 years of operations. A significant fraction of afterglow-phase light curves in…
SN 2023ixf in Messier 101: Photo-ionization of Dense, Close-in Circumstellar Material in a Nearby Type II Supernova
W. V. Jacobson-Galan, L. Dessart, R. Margutti +65
We present UV/optical observations and models of supernova (SN) 2023ixf, a type II SN located in Messier 101 at 6.9 Mpc. Early-time ("flash") spectroscopy of SN 2023ixf, obtained p…
The properties of GRB 120923A at a spectroscopic redshift of z=7.8
N. R. Tanvir, T. Laskar, A. J. Levan +37
Gamma-ray bursts (GRBs) are powerful probes of early stars and galaxies, during and potentially even before the era of reionization. Although the number of GRBs identified at z>6 r…
JWST detection of heavy neutron capture elements in a compact object merger
A. Levan, B. P. Gompertz, O. S. Salafia +80
The mergers of binary compact objects such as neutron stars and black holes are of central interest to several areas of astrophysics, including as the progenitors of gamma-ray burs…
Roaring to softly whispering: Persistent X-ray emission at the location of the Fast Blue Optical Transient AT2018cow 3.7 yrs after discovery and implications on accretion-powered scenarios
G. Migliori, R. Margutti, B. D. Metzger +11
We present the first deep X-ray observations of a luminous FBOT AT2018cow, at since discovery, together with the re-analysis of the observation at …
Hydrogen-Poor Superluminous Supernovae from the Pan-STARRS1 Medium Deep Survey
R. Lunnan, R. Chornock, E. Berger +31
We present light curves and classification spectra of 17 hydrogen-poor superluminous supernovae (SLSNe) from the Pan-STARRS1 Medium Deep Survey (PS1 MDS). Our sample contains all o…
The Swift GRB Host Galaxy Legacy Survey - II. Rest-Frame NIR Luminosity Distribution and Evidence for a Near-Solar Metallicity Threshold
D. A. Perley, N. R. Tanvir, J. Hjorth +9
We present rest-frame NIR luminosities and stellar masses for a large and uniformly-selected population of GRB host galaxies using deep Spitzer Space Telescope imaging of 119 targe…
SVOM GRB 250314A at z 7.3: an exploding star in the era of reionization
B. Cordier, J. Y. Wei, N. R. Tanvir +103
Most long Gamma-ray bursts originate from a rare type of massive stellar explosion. Their afterglows, while rapidly fading, can be initially extremely luminous at optical/near-infr…
Methods for detection and analysis of weak radio sources with single-dish radio telescopes
M. Marongiu, A. Pellizzoni, E. Egron +13
The detection of mJy/sub-mJy point sources is a significant challenge for single-dish radio telescopes. Detection or upper limits on the faint afterglow from GRBs or other sources…
A Reverse Shock and Unusual Radio Properties in GRB 160625B
K. D. Alexander, T. Laskar, E. Berger +9
We present multi-wavelength observations and modeling of the exceptionally bright long -ray burst GRB 160625B. The optical and X-ray data are well-fit by synchrotron emission f…
GOTO identification and broadband modelling of the counterpart to the SVOM GRB 250818B
S. Belkin, G. P. Lamb, K. Ackley +61
Rapid localisation and follow-up of gamma-ray bursts (GRBs) increasingly rely on low-latency triggers from new missions coupled to wide-field robotic optical facilities. We present…
Constraints on Relativistic Jets from the Fast X-ray Transient 210423 using Prompt Radio Follow-Up Observations
Dina Ibrahimzade, R. Margutti, J. S. Bright +16
Fast X-ray Transients (FXTs) are a new observational class of phenomena with no clear physical origin. This is at least partially a consequence of limited multi-wavelength follow u…
Extragalactic Millimeter Transients in the Era of Next Generation CMB Surveys
T. Eftekhari, E. Berger, B. D. Metzger +7
The next generation of wide-field cosmic microwave background (CMB) surveys are uniquely poised to open a new window for time-domain astronomy in the millimeter band. Here we explo…
ALMA Observations of the Host Galaxy of GRB090423 at z=8.23: Deep Limits on Obscured Star Formation 630 Million Years After the Big Bang
E. Berger, B. A. Zauderer, R. -R. Chary +7
We present rest-frame far-infrared (FIR) and optical observations of the host galaxy of GRB090423 at z=8.23 from the Atacama Large Millimeter Array (ALMA) and the Spitzer Space Tel…
The early radio afterglow of short GRB 230217A
G. E. Anderson, G. Schroeder, A. J. van der Horst +9
We present the radio afterglow of short gamma-ray burst (GRB) 230217A, which was detected less than 1 day after the gamma-ray prompt emission with the Australia Telescope Compact A…
The Optical Afterglow of GW170817: An Off-axis Structured Jet and Deep Constraints on a Globular Cluster Origin
Wen-fai Fong, P. K. Blanchard, K. D. Alexander +25
We present a revised and complete optical afterglow light curve of the binary neutron star merger GW170817, enabled by deep Hubble Space Telescope (HST) F606W observations at $\app…
The Swift Gamma-Ray Burst Host Galaxy Legacy Survey - I. Sample Selection and Redshift Distribution
D. A. Perley, T. Krühler, S. Schulze +20
We introduce the Swift Gamma-Ray Burst Host Galaxy Legacy Survey ("SHOALS"), a multi-observatory high-redshift galaxy survey targeting the largest unbiased sample of long-duration…
A Kilonova Following a Long-Duration Gamma-Ray Burst at 350 Mpc
J. C. Rastinejad, B. P. Gompertz, A. J. Levan +32
Here, we report the discovery of a kilonova associated with the nearby (350 Mpc) minute-duration GRB 211211A. In tandem with deep optical limits that rule out the presence of an ac…
Luminous Radio Emission from the Superluminous Supernova 2017ens at 3.3 years after explosion
Raffaella Margutti, J. S. Bright, D. J. Matthews +17
We present the results from a multi-year radio campaign of the superluminous supernova (SLSN) 2017ens, which yielded the earliest radio detection of a SLSN to date at the age of $\…
Lyman continuum leakage in faint star-forming galaxies at redshift z=3-3.5 probed by gamma-ray bursts
J. -B. Vielfaure, S. D. Vergani, J. Japelj +23
We present the observations of Lyman continuum (LyC) emission in the afterglow spectra of GRB 191004B at , together with those of the other two previously known LyC-emitt…
JWST reveals a supernova following a gamma-ray burst at z 7.3
A. J. Levan, B. Schneider, E. Le Floc'h +50
The majority of energetic long-duration gamma-ray bursts (GRBs) are thought to arise from the collapse of massive stars, making them powerful tracers of star formation across cosmi…
Quasi-periodic X-ray eruptions years after a nearby tidal disruption event
M. Nicholl, D. R. Pasham, A. Mummery +61
Quasi-periodic Eruptions (QPEs) are luminous bursts of soft X-rays from the nuclei of galaxies, repeating on timescales of hours to weeks. The mechanism behind these rare systems i…
GRB 241105A: A test case for GRB classification and rapid r-process nucleosynthesis channels
Dimple, B. P. Gompertz, A. J. Levan +85
Gamma-ray bursts (GRBs) offer a powerful window to probe the progenitor systems responsible for the formation of heavy elements through the rapid neutron capture (r-) process, than…
The fraction of ionizing radiation from massive stars that escapes to the intergalactic medium
N. R. Tanvir, J. P. U. Fynbo, A. de Ugarte Postigo +38
The part played by stars in the ionization of the intergalactic medium remains an open question. A key issue is the proportion of the stellar ionizing radiation that escapes the ga…
Dust in the wind: the role of recent mass loss in long gamma-ray bursts
Raffaella Margutti, C. Guidorzi, D. Lazzati +6
We study the late-time (t>0.5 days) X-ray afterglows of nearby (z<0.5) long Gamma-Ray Bursts (GRB) with Swift and identify a population of explosions with slowly decaying, super-so…
Multi-epoch afterglow rebrightenings in GRB 250129A: Evidence for successive shock interactions
D. Akl, S. Antier, H. Koehn +105
Most long gamma-ray bursts (GRBs) exhibit afterglows broadly consistent with external forward-shock emission, typically described by smooth broken power-law decays in the multiband…
Late-time X-ray Observations of the Jetted Tidal Disruption Event AT2022cmc: The Relativistic Jet Shuts Off
T. Eftekhari, A. Tchekhovskoy, K. D. Alexander +9
The tidal disruption event (TDE) AT2022cmc represents the fourth known example of a relativistic jet produced by the tidal disruption of a stray star providing a unique probe of th…
First IFU observations of two GRB host galaxies at cosmic noon with JWST/NIRSpec
B. Topçu, P. Schady, S. Wuyts +16
Long gamma-ray bursts (GRBs) serve as powerful probes of distant galaxies. Their luminous afterglow pinpoints galaxies independent of luminosity, in contrast to most flux-limited s…
An embedded X-ray source shines through the aspherical AT2018cow: revealing the inner workings of the most luminous fast-evolving optical transients
Raffaella Margutti, B. D. Metzger, R. Chornock +41
We present the first extensive radio to gamma-ray observations of a fast-rising blue optical transient (FBOT), AT2018cow, over its first ~100 days. AT2018cow rose over a few days t…
GRB 140515A at z=6.33: Constraints on the End of Reionization From a Gamma-ray Burst in a Low Hydrogen Column Density Environment
R. Chornock, E. Berger, D. B. Fox +3
We present the discovery and subsequent spectroscopy with Gemini-North of the optical afterglow of the Swift gamma-ray burst (GRB) 140515A. The spectrum exhibits a well-detected co…
Two years of non-thermal emission from the binary neutron star merger GW170817: rapid fading of the jet afterglow and first constraints on the kilonova fastest ejecta
A. Hajela, R. Margutti, K. D. Alexander +27
We present Chandra and VLA observations of GW170817 at ~521-743 days post merger, and a homogeneous analysis of the entire Chandra data set. We find that the late-time non-thermal…
Probing Kilonova Ejecta Properties Using a Catalog of Short Gamma-Ray Burst Observations
J. C. Rastinejad, W. Fong, C. D. Kilpatrick +11
The discovery of GW170817 and GRB 170817A in tandem with AT 2017gfo cemented the connection between neutron star mergers, short gamma-ray bursts (GRBs), and kilonovae. To investiga…
Illuminating the Darkest Gamma-Ray Bursts with Radio Observations
B. A. Zauderer, E. Berger, R. Margutti +15
We present X-ray, optical, near-infrared, and radio observations of GRBs 110709B and 111215A, as well as optical and near-IR observations of their host galaxies. The combination of…
Unprecedented X-ray Emission from the Fast Blue Optical Transient AT2022tsd
D. J. Matthews, R. Margutti, B. D. Metzger +8
We present the X-ray monitoring campaign of AT2022tsd in the time range d rest-frame since discovery. With an initial 0.3-10 keV X-ray luminosity of $L_x \a…
EP 250108a/SN 2025kg: Observations of the most nearby Broad-Line Type Ic Supernova following an Einstein Probe Fast X-ray Transient
J. C. Rastinejad, A. J. Levan, P. G. Jonker +66
With a small sample of fast X-ray transients (FXTs) with multi-wavelength counterparts discovered to date, the progenitors of FXTs and their connections to gamma-ray bursts (GRBs)…
Photometric redshift estimation of galaxies in the P\lowercase{an}-STARRS 3 survey- I. Methodology
A. Baldeschi, M. Stroh, R. Margutti +2
We present a photometric redshift (photo-) estimation technique for galaxies in the P\lowercase{an}-STARRS1 (PS1) survey. Specifically, we train and test a regression and…
A mildly relativistic outflow from the energetic, fast-rising blue optical transient CSS161010 in a dwarf galaxy
D. L. Coppejans, R. Margutti, G. Terreran +35
We present X-ray and radio observations of the Fast Blue Optical Transient (FBOT) CRTS-CSS161010 J045834-081803 (CSS161010 hereafter) at t=69-531 days. CSS161010 shows luminous X-r…
The triple-peaked afterglow of GRB 210731A from X-ray to radio frequencies
S. de Wet, T. Laskar, P. J. Groot +18
GRB 210731A was a long-duration gamma-ray burst discovered by the Burst Alert Telescope (BAT) aboard the Neil Gehrels Swift observatory. Swift triggered the wide-field, robotic Mee…
Follow-up of the Neutron Star Bearing Gravitational Wave Candidate Events S190425z and S190426c with MMT and SOAR
G. Hosseinzadeh, P. S. Cowperthwaite, S. Gomez +23
On 2019 April 25.346 and 26.640 UT the LIGO and Virgo gravitational wave (GW) observatories announced the detection of the first candidate events in Observing Run 3 that contain at…
SN 2007it on the RISE -- a radio detection of an interacting supernova 18 years post-explosion
F. Acero, R. Z. E. Alsaberi, M. Arias +17
We report the first detection of radio emission from the Type II supernova SN 2007it, located at a distance of 12.2 Mpc in NGC 5530. The observations were obtained with the Austral…
A second radio flare from the tidal disruption event AT2020vwl: a delayed outflow ejection?
A. J. Goodwin, A. Mummery, T. Laskar +12
We present the discovery of a second radio flare from the tidal disruption event (TDE) AT2020vwl via long-term monitoring radio observations. Late-time radio flares from TDEs are b…
Inverse Compton X-rays from Giant Radio Galaxies at z~1
T. Laskar, A. C. Fabian, K. M. Blundell +1
We report XMM-Newton observations of three FR II radio galaxies at redshifts between 0.85 and 1.34, which show extended diffuse X-ray emission within the radio lobes, likely due to…
The most distant optically polarised GRB afterglow: GRB 240419A at z = 5.178
R. Brivio, S. Covino, M. Ferro +31
Gamma-ray bursts (GRBs) are extremely bright phenomena powered by relativistic jets arising from explosive events at cosmological distances. The nature of the jet and the configura…
Target of Opportunity Observations of Gravitational Wave Events with LSST
R. Margutti, P. Cowperthwaite, Z. Doctor +79
The discovery of the electromagnetic counterparts to the binary neutron star merger GW170817 has opened the era of GW+EM multi-messenger astronomy. Exploiting this breakthrough req…
GRB host galaxies with strong H absorption: CO-dark molecular gas at the peak of cosmic star formation
K. E. Heintz, G. Björnsson, M. Neeleman +13
We present a pilot search of CO emission in three H-absorbing, long-duration gamma-ray burst (GRB) host galaxies at z~2-3. We used the Atacama Large Millimeter/sub-millimeter A…
A robotic pipeline for fast GRB followup with the Las Cumbres observatory network
R. Martone, C. Guidorzi, C. G. Mundell +9
In the era of multi-messenger astronomy the exploration of the early emission from transients is key for understanding the encoded physics. At the same time, current generation net…
Comparing emission- and absorption-based gas-phase metallicities in GRB host galaxies at using JWST
P. Schady, R. M. Yates, L. Christensen +34
Much of what is known of the chemical composition of the universe is based on emission line spectra from star forming galaxies. Emission-based inferences are, nevertheless, model-d…
A Late-Time Galaxy-Targeted Search for the Radio Counterpart of GW190814
K. D. Alexander, G. Schroeder, K. Paterson +14
GW190814 was a compact object binary coalescence detected in gravitational waves by Advanced LIGO and Advanced Virgo that garnered exceptional community interest due to its excelle…
Hydrogen-Poor Superluminous Supernovae and Long-Duration Gamma-Ray Bursts Have Similar Host Galaxies
R. Lunnan, R. Chornock, E. Berger +27
We present optical spectroscopy and optical/near-IR photometry of 31 host galaxies of hydrogen-poor superluminous supernovae (SLSNe), including 15 events from the Pan-STARRS1 Mediu…
A radio-emitting outflow produced by the tidal disruption event AT2020vwl
A. J. Goodwin, K. D. Alexander, J. C. A. Miller-Jones +12
A tidal disruption event (TDE) occurs when a star is destroyed by a supermassive black hole. Broadband radio spectral observations of TDEs trace the emission from any outflows or j…
Discovery of the optical afterglow and host galaxy of short GRB181123B at : Implications for Delay Time Distributions
K. Paterson, W. Fong, A. Nugent +19
We present the discovery of the optical afterglow and host galaxy of the {\it Swift} short-duration gamma-ray burst, GRB\,181123B. Observations with Gemini-North starting at $\appr…
A Reverse Shock in GRB 130427A
T. Laskar, E. Berger, B. A. Zauderer +7
We present extensive radio and millimeter observations of the unusually bright GRB 130427A at z=0.340, spanning 0.67 to 12 days after the burst. Taken in conjunction with detailed…
The first JWST spectrum of a GRB afterglow: No bright supernova in observations of the brightest GRB of all time, GRB 221009A
A. J. Levan, G. P. Lamb, B. Schneider +57
We present JWST and Hubble Space Telescope (HST) observations of the afterglow of GRB 221009A, the brightest gamma-ray burst (GRB) ever observed. This includes the first mid-IR spe…
Towards an understanding of long gamma-ray burst environments through circumstellar medium population synthesis predictions
A. A. Chrimes, B. P. Gompertz, D. A. Kann +8
The temporal and spectral evolution of gamma-ray burst (GRB) afterglows can be used to infer the density and density profile of the medium through which the shock is propagating. I…