Lauren Rhodes
A5009554623- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Radio Astronomy Observations and Technology
- Particle Accelerators and Free-Electron Lasers
- Stellar, planetary, and galactic studies
- High-pressure geophysics and materials
- Superconducting Materials and Applications
- Nuclear Physics and Applications
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Geophysics and Gravity Measurements
- History and Developments in Astronomy
- Laser-Plasma Interactions and Diagnostics
- Structural Health Monitoring Techniques
- Earthquake Detection and Analysis
- Advanced Electrical Measurement Techniques
- SAS software applications and methods
- Computational Physics and Python Applications
- Crystallography and Radiation Phenomena
- Relativity and Gravitational Theory
- RNA and protein synthesis mechanisms
University of Oxford
2019-2025
Space Science Institute
2025
McGill University
2025
Max Planck Institute for Radio Astronomy
2019-2022
St Mary's University Twickenham London
2022
University of Sheffield
2017-2019
Abstract Fast X-ray transients (FXTs) are extragalactic bursts of X-rays first identified in archival data and now routinely discovered real time by the Einstein Probe, which is continuously surveying night sky soft (0.5–4 keV) regime. In this Letter, we report discovery second optical counterpart (AT 2024gsa) to an FXT (EP 240414a). EP 240414a located at a projected radial separation 27 kpc from its likely host galaxy z = 0.4018 ± 0.0010. The light curve AT 2024gsa displays three distinct...
Abstract We present multifrequency (5–345 GHz) and multiresolution radio observations of 1ES 1927+654, widely considered one the most unusual extreme changing-look active galactic nuclei (CL-AGNs). The source was first designated a CL-AGN after an optical outburst in late 2017 has since displayed considerable changes X-ray emission, including destruction rebuilding corona 2019–2020. Radio prior to 2023 show faint compact typical radio-quiet AGN. Starting February, 1927+654 began exhibiting...
Abstract We present deep X-ray and radio observations of the fast blue optical transient (FBOT) AT 2020xnd/ZTF 20acigmel at z = 0.2433 from 13 days to 269 after explosion. 2020xnd belongs category optically luminous FBOTs with similarities archetypal event 2018cow. shows emission reaching L ν ≈ 8 × 10 29 erg s −1 Hz 20 GHz 75 post-explosion, accompanied by rapidly fading soft peaking X 6 42 . Interpreting in context synchrotron radiation explosion’s shock interaction environment, we find...
We present extensive optical photometry of the afterglow GRB~221009A. Our data cover $0.9 - 59.9$\,days from time \textit{Swift} and \textit{Fermi} GRB detections. Photometry in $rizy$-band filters was collected primarily with Pan-STARRS supplemented by multiple 1- to 4-meter imaging facilities. analyzed Swift X-ray found a single decline rate power-law $f(t) \propto t^{-1.556\pm0.002}$ best describes light curve. In addition high foreground Milky Way dust extinction along this line sight,...
Abstract Fast X-ray Transients (FXTs) are extragalactic bursts of soft X-rays first identified ≳10 yr ago. Since then, nearly 40 events have been discovered, although almost all these recovered from archival Chandra and XMM-Newton data. To date, optical sky surveys follow-up searches not revealed any multiwavelength counterparts. The Einstein Probe, launched in 2024 January, has started surveying the regime (0.5–4 keV) will rapidly increase sample FXTs discovered real time. Here we report...
Abstract Quasi-periodic eruptions (QPEs) are luminous X-ray outbursts recurring on hour timescales, observed from the nuclei of a growing handful nearby low-mass galaxies. Their physical origin is still debated, and usually modeled as (a) accretion disk instabilities or (b) interaction supermassive black hole (SMBH) with lower mass companion in an extreme mass-ratio inspiral (EMRI). EMRI models can be tested several predictions related to short- long-term behavior QPEs. In this study, we...
We present the first X-ray spectropolarimetric results for Cygnus X-1 in its soft state from a campaign of five IXPE observations conducted during 2023 May-June. Companion multiwavelength data are likewise shown. The 2-8 keV X-rays exhibit net polarization degree PD=1.99%+/-0.13% (68% confidence). signal is found to increase with energy across IXPE's bandpass. polarized an energy-independent angle PA=-25.7+/-1.8 deg. East North This consistent being aligned Cyg X-1's AU-scale compact radio...
Abstract We present multi-wavelength analysis of ZTF23abelseb (AT 2023sva), an optically discovered fast-fading (Δmr = 2.2 mag in Δt 0.74 days), luminous (Mr ∼ −30.0 mag) and red (g − r 0.50 transient at z 2.28 with accompanying radio emission. AT 2023sva does not possess a γ-ray burst (GRB) counterpart to isotropic equivalent energy limit Eγ, iso < 1.6 × 1052 erg, determined through searching satellite archives between the last non-detection first detection, making it sixth example...
Abstract Fast X-ray transients (FXTs) are a new observational class of phenomena with no clear physical origin. This is at least partially consequence limited multiwavelength follow-up this in real time. Here we present deep optical ( g - and i -band) photometry Keck, prompt radio observations the Very Large Array FXT 210423 obtained δ t ≈ 14–36 days since trigger. We use these multiband observations, combined publicly available data sets, to constrain presence properties on-axis off-axis...
We present 11 detections of FRB 121102 in ~3 hours observations during its 'active' period on the 10th September 2019. The were made using newly deployed MeerTRAP system and single pulse detection pipeline at MeerKAT radio telescope South Africa. Fortuitously, Nancay this day overlapped with last hour resulted 4 simultaneous detections. MeerKAT's wide band receiver, which extends down to relatively low frequencies (900-1670 MHz usable L-band range), have allowed us get a detailed look...
Abstract The deaths of massive stars are sometimes accompanied by the launch highly relativistic and collimated jets. If jet is pointed towards Earth, we observe a ‘prompt’ gamma-ray burst due to internal shocks or magnetic reconnection events within jet, followed long-lived broadband synchrotron afterglow as interacts with circumburst material. While there solid observational evidence that emission from multiple contributes signature, detailed studies reverse shock, which travels back into...
ABSTRACT Tidal disruption events (TDEs) are transient, multiwavelength in which a star is ripped apart by supermassive black hole. Observations show that small fraction of TDEs, short-lived, synchrotron emitting jet produced. We observed the newly discovered TDE AT2022cmc with slew radio facilities over first 100 d after its discovery. The light curve from Arcminute Microkelvin Imager Large Array interferometer shows day-time-scale variability we attribute to high brightness temperature...
ABSTRACT The Tidal Disruption Event (TDE) AT 2018hyz exhibited a delayed radio flare almost three years after the stellar disruption. Here, we report new observations of TDE with AMI-LA and ATCA spanning from month to more than four optical discovery 200 d since last reported observation. We detected no emission 30–220 in our at 15.5 GHz down 3σ level <0.14 mJy. fast-rising, is observed data set continues rise ∼1580 discovery. find that emission, first 972 discovery, evolves as t4.2 ±...
We present high cadence multi-frequency radio observations of the long Gamma-Ray Burst (GRB) 190829A, which was detected at photon energies above 100 GeV by High Energy Stereoscopic System (H.E.S.S.). Observations with Meer Karoo Array Telescope (MeerKAT, 1.3 GHz), and Arcminute Microkelvin Imager - Large (AMI-LA, 15.5 GHz) began one day post-burst lasted nearly 200 days. used complementary data from Swift X-Ray (XRT), ran to days post-burst. a likely forward shock component both MeerKAT XRT...
Abstract We present the discovery and extensive follow-up of a remarkable fast-evolving optical transient, AT 2022aedm, detected by Asteroid Terrestrial impact Last Alert Survey (ATLAS). In ATLAS o band, 2022aedm exhibited rise time 9 ± 1 days, reaching luminous peak with M g ≈ −22 mag. It faded 2 mag in band during next 15 days. These timescales are consistent other rapidly evolving transients, though luminosity is extreme. Most surprisingly, host galaxy massive elliptical negligible...
Abstract We present the discovery of radio afterglow short gamma-ray burst (GRB) 210726A, localized to a galaxy at photometric redshift z ∼ 2.4. While observations commenced ≲1 day after burst, no emission was detected until ∼11 days. The subsequently brightened by factor ∼3 in span week, followed rapid decay (a “radio flare”). find that forward shock model cannot self-consistently describe multiwavelength X-ray and data, underpredicts flux flare ≈5. addition substantial energy injection,...
We present ultraviolet, optical and infrared photometry spectroscopy of the type Ic superluminous supernova (SLSN) Gaia16apd (= SN 2016eay), covering its evolution from 26 d before $g$-band peak to 234.1 after peak. was followed as a part NOT Unbiased Transient Survey (NUTS). It is one closest SLSNe known ($z = 0.102\pm0.001$), with detailed ultraviolet (UV) observations spectroscopically typical SLSN, exhibiting characteristic blue early spectra O II absorption, reaches $M_{g} -21.8 \pm...
The Galactic black hole transient GRS1915+105 is famous for its markedly variable X-ray and radio behaviour, being the archetypal galactic source of relativistic jets. It entered an outburst in 1992 has been active ever since. Since 2018 declined into extended low-flux plateau, occasionally interrupted by multi-wavelength flares. Here we report properties collected this new phase, compare recent data to historic observations. We find that while emission remained unprecedentedly low most time...
We present a detailed study of the complex time-frequency structure sample previously reported bursts FRB 121102 detected with MeerKAT telescope in September 2019. The wide contiguous bandwidth these observations have revealed bifurcating some at $1250$ MHz. When de-dispersed to their structure-optimised dispersion measures, two show clear deviation from cold plasma relationship below find differential measure ${\sim}1{-}2$ pc cm$^{-3}$ between lower and higher frequency regions each burst....
Cygnus X-3 is an enigmatic X-ray binary that both exceptional accreting system and a cornerstone for population synthesis studies. Prominent radio properties follow well-defined pattern, yet the physical reasons state changes observed in this are not known. Recently, presence of optically thick envelope around central source hard was revealed using polarization data obtained with Imaging Polarimetry Explorer (IXPE). In work we analyse IXPE ultrasoft (radio quenched) source. The average...
In this work we study the circumstellar material (CSM) around massive stars, and mass-loss rates depositing CSM, using a large sample of radio observations 325 core-collapse supernovae (CCSNe; only $\sim 22 \%$ them being detected). This comprises both archival data our new 99 CCSNe conducted with AMI-LA array in systematic approach devised to constrain at different stages stellar evolution. SN-CSM interaction model, observing peak emission SN provides CSM density given radius (and therefore...
Abstract In this work, we study the circumstellar material (CSM) around massive stars, and mass-loss rates depositing CSM, using a large sample of radio observations 325 core-collapse supernovae (CCSNe; only ~22% them being detected). This comprises both archival data our new 99 CCSNe conducted with AMI-LA array in systematic approach devised to constrain mass loss at different stages stellar evolution. supernova (SN)–CSM interaction model, observing peak emission an SN provides CSM density...
Astrophysical observations of the cosmos allow us to probe extreme physics and answer foundational questions on our universe. Modern astronomy is increasingly operating under a holistic approach, probing same question with multiple diagnostics including how sources vary over time, they appear across electromagnetic spectrum, through their other signatures, gravitational waves, neutrinos, cosmic rays, dust Earth. are now reaching point where approximate models insufficient. Key interest...