Search Publications
An Updated Mass-Radius Analysis of the 2017-2018 NICER Data Set of PSR J0030+0451
Chakrabarty, Deepto; Bogdanov, Slavko; Salmi, Tuomo +12 more
In 2019 the NICER collaboration published the first mass and radius inferred for PSR J0030+0451, thanks to NICER observations, and consequent constraints on the equation of state characterizing dense matter. Two independent analyses found a mass of ~1.3-1.4 M ⊙ and a radius of ~13 km. They also both found that the hot spots were all loc…
A NICER View of the Nearest and Brightest Millisecond Pulsar: PSR J0437–4715
Remillard, Ronald A.; Bogdanov, Slavko; Salmi, Tuomo +17 more
We report Bayesian inference of the mass, radius, and hot X-ray emitting region properties—using data from the Neutron Star Interior Composition ExploreR (NICER)—for the brightest rotation-powered millisecond X-ray pulsar, PSR J0437‑4715. Our modeling is conditional on informative tight priors on mass, distance, and binary inclination obtained fro…
ULTRASAT: A Wide-field Time-domain UV Space Telescope
Mazeh, T.; Gal-Yam, A.; Tal-Or, L. +41 more
The Ultraviolet Transient Astronomy Satellite (ULTRASAT) is scheduled to be launched to geostationary orbit in 2027. It will carry a telescope with an unprecedentedly large field of view (204 deg2) and near-ultraviolet (NUV; 230–290 nm) sensitivity (22.5 mag, 5σ, at 900 s). ULTRASAT will conduct the first wide-field survey of transient …
The Radius of the High-mass Pulsar PSR J0740+6620 with 3.6 yr of NICER Data
Chakrabarty, Deepto; Bogdanov, Slavko; Salmi, Tuomo +14 more
We report an updated analysis of the radius, mass, and heated surface regions of the massive pulsar PSR J0740+6620 using Neutron Star Interior Composition Explorer (NICER) data from 2018 September 21 to 2022 April 21, a substantial increase in data set size compared to previous analyses. Using a tight mass prior from radio-timing measurements and …
Deep Synoptic Array Science: First FRB and Host Galaxy Catalog
Hallinan, Gregg; Hodges, Mark; Lamb, James W. +19 more
Fast radio bursts (FRBs) are a powerful and mysterious new class of transients that are luminous enough to be detected at cosmological distances. By associating FRBs to host galaxies, we can measure intrinsic and environmental properties that test FRB origin models, in addition to using them as precise probes of distant cosmic gas. The Deep Synopt…
A Systematic Analysis of the X-Ray Emission in Optically Selected Tidal Disruption Events: Observational Evidence for the Unification of the Optically and X-Ray-selected Populations
Cenko, S. Bradley; van Velzen, Sjoert; Gezari, Suvi +4 more
We present a systematic analysis of the X-ray emission of a sample of 17 optically selected, X-ray-detected tidal disruption events (TDEs) discovered between 2014 and 2021. The X-ray light curves show a diverse range of temporal behaviors, with most sources not following the expected power-law decline. The X-ray spectra are mostly extremely soft a…
A More Precise Measurement of the Radius of PSR J0740+6620 Using Updated NICER Data
Bogdanov, Slavko; Wolff, Michael T.; Arzoumanian, Zaven +9 more
PSR J0740+6620 is the neutron star with the highest precisely determined mass, inferred from radio observations to be 2.08 ± 0.07 M ⊙. Measurements of its radius therefore hold promise to constrain the properties of the cold, catalyzed, high-density matter in neutron star cores. Previously, Miller et al. and Riley et al. reported measur…
A New Population of Mid-infrared-selected Tidal Disruption Events: Implications for Tidal Disruption Event Rates and Host Galaxy Properties
Meisner, Aaron M.; Simcoe, Robert A.; Eilers, Anna-Christina +14 more
Most tidal disruption events (TDEs) are currently found in time-domain optical and soft X-ray surveys, both of which are prone to significant obscuration. The infrared (IR), however, is a powerful probe of dust-enshrouded environments; hence, we recently performed a systematic search of NEOWISE mid-IR data for nearby, obscured TDEs within roughly …
Testing EMRI Models for Quasi-periodic Eruptions with 3.5 yr of Monitoring eRO-QPE1
Remillard, Ronald A.; Maccarone, Thomas J.; Burdge, Kevin B. +13 more
Quasi-periodic eruptions (QPEs) are luminous X-ray outbursts recurring on hour timescales, observed from the nuclei of a growing handful of nearby low-mass galaxies. Their physical origin is still debated, and usually modeled as (a) accretion disk instabilities or (b) interaction of a supermassive black hole (SMBH) with a lower mass companion in a…
A NICER View of PSR J1231‑1411: A Complex Case
Bogdanov, Slavko; Salmi, Tuomo; Deneva, Julia S. +16 more
Recent constraints on neutron star mass and radius have advanced our understanding of the equation of state (EOS) of cold dense matter. Some of them have been obtained by modeling the pulses of three millisecond X-ray pulsars observed by the Neutron Star Interior Composition Explorer (NICER). Here, we present a Bayesian parameter inference for a f…