A5091872255- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- earthquake and tectonic studies
- Atomic and Subatomic Physics Research
- Superconducting Materials and Applications
- Advanced X-ray and CT Imaging
- Seismic Waves and Analysis
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Control Systems and Identification
- Magnetic confinement fusion research
- Bacillus and Francisella bacterial research
- Radioactivity and Radon Measurements
- GNSS positioning and interference
- Nuclear physics research studies
- Coastal and Marine Dynamics
- Digital Radiography and Breast Imaging
- Machine Learning in Healthcare
- Paleopathology and ancient diseases
Stockholm University
2022-2025
AlbaNova
2022-2025
KTH Royal Institute of Technology
2022-2025
Monash University
2017-2024
Australian Regenerative Medicine Institute
2024
Nordic Institute for Theoretical Physics
2024
ARC Centre of Excellence for Gravitational Wave Discovery
2017-2023
Australian Research Council
2021
Bayesian parameter estimation is fast becoming the language of gravitational-wave astronomy. It method by which data used to infer sources' astrophysical properties. We introduce a user-friendly inference library for astronomy, Bilby. This python code provides expert-level infrastructure with straightforward syntax and tools that facilitate use beginners. allows users perform accurate reliable on both real, freely-available from LIGO/Virgo, simulated data. provide suite examples analysis...
ABSTRACT Gravitational waves provide a unique tool for observational astronomy. While the first LIGO–Virgo catalogue of gravitational-wave transients (GWTC-1) contains 11 signals from black hole and neutron star binaries, number observations is increasing rapidly as detector sensitivity improves. To extract information observed signals, it imperative to have fast, flexible, scalable inference techniques. In previous paper, we introduced bilby: modular user-friendly Bayesian library adapted...
The mergers of binary compact objects such as neutron stars and black holes are central interest to several areas astrophysics, including the progenitors gamma-ray bursts (GRBs), sources high-frequency gravitational waves likely production sites for heavy element nucleosynthesis via rapid capture (the r-process). These elements include some great geophysical, biological cultural importance, thorium, iodine gold. Here we present observations exceptionally bright burst GRB 230307A. We show...
ABSTRACT Fulfilling the rich promise of rapid advances in time-domain astronomy is only possible through confronting our observations with physical models and extracting parameters that best describe what we see. Here, introduce redback; a Bayesian inference software package for electromagnetic transients. redback provides an object-orientated python interface to over 12 different samplers 100 kilonovae, supernovae, gamma-ray burst afterglows, tidal disruption events, engine-driven...
Abstract One of the open questions following discovery GW170817 is whether neutron star (NS) mergers are only astrophysical sites capable producing r -process elements. Simulations have shown that 0.01–0.1 M ⊙ material could be generated in outflows originating from accretion disk surrounding rapidly rotating black hole forms as a remnant to both NS and collapsing massive stars associated with long-duration gamma-ray bursts (collapsars). The hallmark signature nucleosynthesis binary merger...
Short gamma-ray bursts are believed to be produced by both binary neutron star (BNS) and star-black hole (NSBH) mergers. We use current estimates for the BNS NSBH merger rates calculate fraction of observable short through each channel. This allows us constrain $\mathcal{R}_{\rm{BNS}}=384^{+431}_{-213}{\rm{Gpc}^{-3} \rm{yr}^{-1}}$ ($90\%$ credible interval), a $16\%$ decrease in rate uncertainties from second LIGO--Virgo Gravitational-Wave Transient Catalog, GWTC-2. Assuming top-hat emission...
Stars with zero-age main sequence masses between 140 and 260 M ⊙ are thought to explode as pair-instability supernovae (PISNe). During their thermonuclear runaway, PISNe can produce up several tens of solar radioactive nickel, resulting in luminous transients similar some superluminous (SLSNe). Yet, no unambiguous PISN has been discovered so far. SN 2018ibb is a hydrogen-poor SLSN at z = 0.166 that evolves extremely slowly compared the hundreds known SLSNe. Between mid 2018 early 2022, we...
ABSTRACT Neutron star (NS) mergers where both stars have negligible spins are commonly considered as the most likely ‘standard’ case. In globular clusters, however, majority of NSs been spun up to millisecond (ms) periods and, based on observed systems, we estimate that a non-negligible fraction all double NS ($\sim 4\pm 2\, {{\ \rm per\ cent}}$) contains one component with spin (few) ms. We use Lagrangian numerical relativity code SPHINCS_BSSN simulate has no and other dimensionless...
We infer the collapse times of long-lived neutron stars into black holes using X-ray afterglows 18 short gamma-ray bursts. then apply hierarchical inference to properties star equation state and dominant spin-down mechanism. measure maximum non-rotating mass $M_\mathrm{TOV} = 2.31 ^{+0.36}_{-0.21} M_{\odot}$ constrain fraction remnants spinning down predominantly through gravitational-wave emission $\eta 0.69 ^{+0.21}_{-0.39}$ with $68 \%$ uncertainties. In principle, this method can...
ABSTRACT A non-negligible fraction of binary neutron star mergers are expected to form long-lived remnants, dramatically altering the multimessenger signatures a merger. Here, we extend existing models for magnetar-driven kilonovae and explore diversity kilonova afterglows. Focusing on role (uncertain) magnetic field strength, study resulting electromagnetic as function external dipolar internal toroidal fields. These two parameters govern, respectively, competition between magnetic-dipole...
Abstract The cooling envelope model for tidal disruption events (TDEs) postulates that while the stellar debris streams rapidly dissipate their bulk kinetic energy (“circularize”), this does not necessarily imply rapid feeding of supermassive black hole (SMBH). bound material instead forms a large pressure-supported powers optical/UV emission as it undergoes gradual Kelvin–Helmholtz contraction. We present results interpreting sample 15 optical TDEs within in order to constrain SMBH mass M...
Abstract A major ingredient for kilonova lightcurves is the radioactive heating rate and its dependence on electron fraction velocity of ejecta and, in principle, nuclear mass formula. Heating-rate formulae commonly used as basis models previously employed literature produce substantially different outputs high fractions ( Y e ≳ 0.3) at late times t 1 day) compared to newer prescriptions. Here, we employ standard semianalytical kilonovae with better prescriptions valid full parameter space...
Detections of fast X-ray transients (FXTs) have been accrued over the last few decades. However, their origin has remained mysterious. There is now rapid progress thanks to timely discoveries and localisations with Einstein Probe mission. Early results indicate that FXTs may frequently, but not always, be associated gamma-ray bursts (GRBs). Here, we report on multi-wavelength counterpart FXT EP240414a, which no reported counterpart. The transient located 25.7~kpc in projection from a massive...
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 The ejection of neutron-rich matter is one the most important consequences a neutron star merger. While bulk ejected at fast, but non-relativistic velocities (∼0.2c), small amount mildly relativistic dynamic ejecta have been seen in number numerical simulations. Such can far reaching observational ranging from shock breakout burst gamma-rays promptly after merger, to an early (∼1 hour post-merger) blue kilonova precursor signal, synchrotron emission years merger (‘kilonova...
Over the past two decades, an increasing number of transients have shown luminous activity at their explosion sites weeks to years before interacting supernova (SN) is observed. For some objects, this pre-SN typically linked large-scale mass-loss events preceding core collapse, yet its triggering mechanism and underlying process remain uncertain. We present SN 2022mop, which was initially observed in August 2022, exhibiting nebular emission, including [O I], Mg [Ca II], resembling late-time...
ABSTRACT Several types of energetic supernovae, such as superluminous supernovae (SLSNe) and broad-line Ic (Ic-BL SNe), could be powered by the spin-down a rapidly rotating magnetar. Currently, most models used to infer parameters for potential magnetar-driven make several unsuitable assumptions that likely bias estimated parameters. In this work, we present new model relaxes these an inference workflow enables accurate estimation from light curves supernovae. particular, in model, include...
X-ray observations of some short gamma-ray bursts indicate that a long-lived neutron star can form as remnant binary merger. We develop gravitational-wave detection pipeline for merger guided by these counterpart electromagnetic observations. determine the distance out to which signal be detected with Advanced LIGO at design sensitivity and Einstein Telescope using this method, x-ray data from GRB140903A an example. Such gravitational waves can, in principle, $\ensuremath{\sim}20\text{...
Abridged - Stars with ZAMS masses between 140 and $260 M_\odot$ are thought to explode as pair-instability supernovae (PISNe). During their thermonuclear runaway, PISNe can produce up several tens of solar radioactive nickel, resulting in luminous transients similar some superluminous (SLSNe). Yet, no unambiguous PISN has been discovered so far. SN2018ibb is a H-poor SLSN at $z=0.166$ that evolves extremely slowly compared the hundreds known SLSNe. Between mid 2018 early 2022, we monitored...
Abstract Proposed next-generation networks of gravitational-wave observatories include dedicated kilohertz instruments that target neutron star science, such as the proposed Neutron Star Extreme Matter Observatory, NEMO. The original proposal for NEMO highlighted need it to exist in a network ensure detection confidence and sky localisation sources. We show NEMO-like have significant utility on their own coincident electromagnetic observations can provide significance localisation. that,...
The nature of the minute-to-hour long Fast X-ray Transients (FXTs) localised by telescopes such as Chandra, Swift, and XMM-Newton remains mysterious, with numerous models suggested for events. Here, we report multi-wavelength observations EP240315a, a 1600 s transient detected Einstein Probe, showing it to have redshift z=4.859. We measure low column density neutral hydrogen, indicating that event is embedded in low-density environment, further supported direct detection leaking ionising...
The spin-down energy of millisecond magnetars has been invoked to explain X-ray afterglow observations a significant fraction short and long gamma-ray bursts. Here, we extend models previously introduced in the literature, incorporating radiative losses with spin down magnetar central engine through an arbitrary braking index. Combining this model for tail prompt emission, show that our can better data than millisecond-magnetar without or those invoke solely vacuum dipole radiation. We find...
Abstract The origin of the X-ray afterglows gamma-ray bursts has regularly been debated. We fit both fireball-shock and millisecond-magnetar models to data GRB 130603B 140903A. use Bayesian model selection answer question which best explains data. This is dependent on maximum allowed non-rotating neutron star mass M TOV , depends solely unknown nuclear equation state. show that for 140903A favors all possible equations state, while if ≳ 2.3 ⊙ . If ≲ supports model. discuss implications this...
The Zwicky Transient Facility recently announced the detection of an optical transient AT2020blt at redshift $z=2.9$, consistent with afterglow on-axis gamma-ray burst. However, no prompt emission was observed. We analyse detailed models, showing data are best explained as long burst, ruling out other hypotheses such a cocoon and low-Lorentz factor jet. search \textit{Fermi} for emission, setting deeper upper limits on than in original paper. Together KONUS-\textit{Wind} observations, we...