Description
Organisers: Aysha Aamer, Edward Charleton, Benjamin Godson, Joshua Pollin, Ana Sainz de Murieta, Xinyue Sheng, Ben Warwick
This session aims to explore the present and future sky of extragalactic transients. These explosive events provide invaluable insights into the universeโs most extreme environments, encompassing phenomena such as the diverse range of supernovae, tidal disruption events (TDEs), and superluminous supernovae (SLSNe). Beyond driving nucleosynthesis and shaping star formation, some of these events also serve as vital cosmological distance indicators.
Despite significant progress, many intriguing questions remain unanswered, and the arrival of extensive surveys like LSST and 4MOST promises to increase this discovery rate by a further order of magnitude. Simultaneously, a new generation of space missions (SVOM, EP) are already providing novel insights and challenges to our understanding of the high-energy regime. In this era of big data, machine learning and AI are being increasingly employed across various stages of survey pipelines, enabling more efficient and effective searches for these transients, but it is crucial to understand where these methods excel, and where they are limited.
The primary aim of our session will be to bring together members of the UK transient community to showcase new observational and theoretical results and current projects in the field. This includes talks on a broad range of extragalactic astrophysical transients to disseminate ideas and foster collaboration between those working across the complete spectrum of transient types, wavelengths, and messengers. We also encourage talks looking at the science being facilitated by current and future photometric and spectroscopic facilities to promote discussion on future projects.
Type Ia supernovae (SNe Ia) have played an important role in both astrophysical and cosmological analyses. Traditionally, these analyses rely on precise spectroscopic measurements of either the supernova or its host galaxy. The Vera C. Rubin Observatory Legacy Survey of Space and Time is expected to begin operations in early 2026, and will discover and measure millions of SNe Ia. However,...
The detection of the kilonova AT2017gfo has provided us with a wealth of observations. However, to interpret these observations to obtain information about the underlying merger ejecta, including r-process nucleosynthesis, we are reliant on kilonova modelling. The majority of binary neutron star ejecta models considered when simulating kilonovae have been in 1D, or even idealised toy models,...
One of the most promising models to explain SLSNe is the magnetar model. In this scenario, the spin-down energy from a rapidly-rotating neutron star is injected into the supernova ejecta via a pulsar wind nebula (PWN). The PWN both accelerates the ejecta and produces broadband emission that is absorbed and thermalized in the ejecta. Since the light curves of magnetar-driven SLSNe are...
The rare and mysterious class of event sometimes known as luminous fast blue optical transients, typefied by the event AT2018cow, has provided a steady stream of surprises over the past five years: they are extremely radio-luminous, highly X-ray variable, and at least in some cases they produce ultra-fast optical flares for months and leave behind a hot remnant. While the emission from...
Over time, core-collapse supernova (CCSN) spectra become redder due to dust formation and cooling of the SN ejecta. A UV detection of a CCSN at late times is thus atypical. Additionally, a late time UV detection of a peculiar transient can therefore provide diagnostics as to their nature. An example of this is AT2018cow, a peculiar transient that was still UV-bright four years after it was...
Extreme coronal line emitters (ECLEs) are a composite population of tidal disruption events (TDEs) and exotic active galactic nuclei (AGNs) displaying emission lines from highly ionised iron (FeVII - FeXIV). These lines are produced through the reprocessing of high energy X-ray photons by gas-rich environments. The TDE-linked subpopulation of these events also displays a distinctive...
We present Optical/UV photometric and spectroscopic observations, as well as X-ray and radio follow-up, of the extraordinary event AT2019cmw. With a peak bolometric luminosity of ~10^45.6 erg/s, it is one of the most luminous thermal transients ever discovered. Extensive spectroscopic follow-up post-peak showed only a featureless continuum throughout its evolution. This, combined with its...
Tidal disruption events (TDEs) are rare transients that occur when stars are torn apart by black holes and accreted. At X-ray energies, they are typically soft, thermal sources that slowly evolve over years or even decades, or harder sources produced by relativistic jets that decay rapidly when the jet turns off. In this talk, I will discuss a unique source discovered in archival Swift-XRT...
Tidal disruption events (TDEs) provide insights into the extreme environments of galactic nuclei, revealing central SMBHs and their host galaxy connection. These events are over-represented in โpost-starburstโ galaxies, which have unusual star formation histories (SFHs), high central densities, and a position in the โgreen valley.โ Understanding how these properties influence TDE rates is key...
The Vera C. Rubin Observatoryโs 10-Year Legacy Survey of Space and Time (LSST) will transform time-domain astronomy, increasing the number of observed transients a hundredfold. For tidal disruption events (TDEs), this means a leap from ~100 to ~50,000, offering a unique opportunity to answer key open questions: Can we observe intermediate-mass black holes through TDEs? Why do TDEs prefer...
Gravitationally lensed supernovae (glSNe) are powerful local probes of the Hubble parameter ($H_{0}$), as they are independent of the distance ladder and insensitive to the assumed cosmological model. Despite their rarity, the Rubin Observatoryโs Legacy Survey of Space and Time (Rubin-LSST) will increase the sample of known glSNe by an order of magnitude. In this talk, we present a...
Over the next decade, large survey telescopes, such as the Large Synoptic Space Telescope (LSST), are expected to yield hundreds to thousands of detections of gravitationally lensed supernovae, offering unprecedented advances in the study of these phenomena. Of particular note is the expected prevalence of Type IIn supernovae, which, with over 200 detections expected per year, dominate the...
During the last decade, the increase in survey depth, cadence, and sky coverage has led to a significant increase in the number of discovered supernovae (SNe), and more importantly the number of SNe discovered soon after explosion. Discovering SNe within days of explosion enables investigation into the outer density profile of progenitor stars, and/or the presence of significant circumstellar...
Late-timeย shockย interactionย between supernova (SN) ejecta and circumstellar material (CSM) offers a powerful probe of the mass-loss history of massive stars and the dynamics of stellar explosions. Thisย interactionย is critical for understanding the final stages of stellarย evolutionย and the diversity ofย core-collapseย supernovaeย (CCSNe). Whileย shockย interactionย signatures have been observed in a...
Interacting transients provide invaluable insights into the final moments of the lives of massive stars, unveiling the mechanisms of pre-explosion mass loss, and tracing the amount, composition, and geometry of the CSM resulting from these processes.
I will present the transitional IIn SN 2024cld, discovered and classified just 12h post-explosion through the GOTO-FAST survey, and...
Fast radio bursts (FRBs) are intense pulses of radio emission occurring on timescales of milliseconds with yet unknown progenitors. To help solve their mysterious origin, as well as better use FRBs as powerful tools for cosmology study and galaxy gas dynamics, effective localisation of FRBs to their host galaxies and follow-up observations are necessary. I present recent results from the...
Thermonuclear bursts are explosive flashes of X-rays caused byunstable nuclear burning of accreted material on the surface of aneutron star in a low-mass X-ray binary (LMXB). Observing coolingbehaviors of these bursts provide crucial insights into the nuclearburning processes on the surface of accreting neutron stars. In thisstudy, we analyze 39 different bursts from the neutron star...
The upcoming Vera C. Rubin Observatory Legacy Survey of Space and Time (LSST) will enable astronomers to discover rare and distant astrophysical transients. Host-galaxy association is crucial for selecting the most scientifically interesting transients for follow-up. While this association is currently carried out using large all-sky catalogues, LSSTโs Deep Drilling Fields will probe the night...
The Living Swift-XRT Point Source Catalogue (LSXPS) is a unique facility: it is updated in near real-time, enabling a sensitive, โliveโ search for new high-energy transients. This opens up a new area of transient phase-space for exploration, as evidenced by the LSXPS discovery of the enigmatic event Swift J0230. However, the majority of transient candidates detected are faint, classified as...
I will present an investigation into the circumstellar material (CSM) surrounding simulated progenitors of Type Ib/cn supernovae (SNe), using models from the Binary Populations and Spectral Synthesis (BPASS) code. Type Ib/cn SNe are rare, and due to the limited observational data, their progenitor systems remain poorly understood. Their spectra reveal signatures of dense CSM, but the origins...
SuperSMART is a novel concept to enable medium resolution optical and near-IR spectrophotmetry for a wide range of science cases, with a specific focus on the field of Time Domain Astronomy. It is based around an array of 'small' (0.6-1.0m) commercial telescopes which each feed light independently via one or more fibers to a cryostat containing an array of Microwave Kinetic Inductance...
The STONKS pipeline, developed for XMM-Newton, is lifting the curtain on a new population of highly variable X-ray sources. Now a part of the XMM pipeline, STONKS examines all detected sources in observations and automatically alerts the community to variable and transient sources, using a multi-mission X-ray source catalogue. By repurposing the capabilities of a pointing X-ray observatory...
