A5019699998- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- High-pressure geophysics and materials
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Geophysics and Gravity Measurements
- Astrophysics and Cosmic Phenomena
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Mechanics and Biomechanics Studies
- Scientific Research and Discoveries
- Astrophysics and Star Formation Studies
- Isotope Analysis in Ecology
- Geomagnetism and Paleomagnetism Studies
- Genetics, Bioinformatics, and Biomedical Research
- Galaxies: Formation, Evolution, Phenomena
- Statistical and numerical algorithms
- Time Series Analysis and Forecasting
- Radio Astronomy Observations and Technology
- Spectroscopy and Chemometric Analyses
- Statistics Education and Methodologies
- Superconducting Materials and Applications
- Biomedical and Engineering Education
University of Amsterdam
2009-2025
SRON Netherlands Institute for Space Research
2021-2025
Astronomical Institute of the Slovak Academy of Sciences
2025
University of Washington
2017-2021
Washington Research Foundation
2018-2021
City University of Seattle
2018-2021
New York University
2015-2018
Jacobi Medical Center
2016
The Netherlands Cancer Institute
2010
The Zwicky Transient Facility (ZTF) is a new optical time-domain survey that uses the Palomar 48 inch Schmidt telescope. A custom-built wide-field camera provides 47 deg2 field of view and 8 s readout time, yielding more than an order magnitude improvement in speed relative to its predecessor survey, Factory. We describe design implementation observing system. ZTF data system at Infrared Processing Analysis Center near-real-time reduction identify moving varying objects. outline analysis...
The Zwicky Transient Facility (ZTF), a public-private enterprise, is new time domain survey employing dedicated camera on the Palomar 48-inch Schmidt telescope with 47 deg$^2$ field of view and 8 second readout time. It well positioned in development astronomy, offering operations at 10% scale style Large Synoptic Survey Telescope (LSST) single 1-m class telescope. public surveys will cover observable northern sky every three nights g r filters visible Galactic plane night r. Alerts...
Abstract We report the discovery of GRB 221009A, highest flux gamma-ray burst (GRB) ever observed by Fermi Gamma-ray Burst Monitor (Fermi-GBM). This has continuous prompt emission lasting more than 600 s, which smoothly transitions to afterglow visible in Fermi-GBM energy range (8 keV–40 MeV), and total energetics higher any other sample. By using a variety new existing analysis techniques we probe spectral temporal evolution 221009A. find no prior trigger time ( t 0 ; 2022 October 9 at...
Abstract In 2019 the NICER collaboration published first mass and radius inferred for PSR J0030+0451, thanks to observations, consequent constraints on equation of state characterizing dense matter. Two independent analyses found a ∼1.3–1.4 M ⊙ ∼13 km. They also both that hot spots were all located same hemisphere, opposite observer, at least one them had significantly elongated shape. Here we reanalyze, in greater detail, data set, incorporating effects an updated response matrix using...
Abstract We report Bayesian inference of the mass, radius, and hot X-ray emitting region properties—using data from Neutron Star Interior Composition ExploreR (NICER)—for brightest rotation-powered millisecond pulsar, PSR J0437−4715. Our modeling is conditional on informative tight priors distance, binary inclination obtained radio pulsar timing using Parkes Pulsar Timing Array (PPTA; Reardon et al.), we use NICER background models to constrain nonsource background, cross-checking with...
Abstract We report an updated analysis of the radius, mass, and heated surface regions 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 set size compared previous analyses. Using tight mass prior radio-timing measurements jointly modeling new NICER with XMM-Newton data, inferred equatorial radius gravitational are <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"...
Supernova remnants (SNRs) are a complex class of sources, and their heterogeneous nature has hindered the characterization general observational properties. To overcome this challenge, in paper, we use statistical tools to analyze Chandra X-ray images Galactic Large Magellanic Cloud SNRs. We apply two techniques, power-ratio method (a multipole expansion) wavelet-transform analysis, measure global local morphological properties line thermal emission 24 find that Type Ia SNRs have...
We report on $g$, $r$ and $i$ band observations of the Interstellar Object 'Oumuamua (1I) taken 2017 October 29 from 04:28 to 08:40 UTC by Apache Point Observatory (APO) 3.5m telescope's ARCTIC camera. find that 1I's colors are $g-r=0.41\pm0.24$ $r-i=0.23\pm0.25$, consistent with visible spectra Masiero (2017), Ye et al. (2017) Fitzsimmons most comparable population Solar System C/D asteroids, Trojans, or comets. no evidence any cometary activity at a heliocentric distance 1.46 au,...
Quasi-periodic oscillations (QPOs) are often present in the X-ray flux from accreting stellar-mass black holes (BHs). If they due to relativistic (Lense-Thirring) precession of an inner accretion flow which is misaligned with disc, iron emission line caused by irradiation disc will rock systematically between red and blue shifted during each QPO cycle. Here we conduct phase-resolved spectroscopy a $\sim2.2$ Hz type-C BH binary GRS 1915+105, observed simultaneously NICER NuSTAR. We apply...
Abstract We analyzed broadband X-ray and radio data of the magnetar SGR J1935+2154 taken in aftermath its 2014, 2015, 2016 outbursts. The source soft spectrum <10 keV is well described with a blackbody+power-law (BB+PL) or 2BB model during all three Nuclear Spectroscopic Telescope Array observations revealed hard tail, PL photon index Γ = 0.9, extending up to 50 keV, flux comparable one detected keV. Imaging analysis Chandra did not reveal small-scale extended emission around source....
Significance As scientific disciplines grapple with more datasets of rapidly increasing complexity and size, new approaches are urgently required to introduce statistical computational tools into research communities improve the cross-disciplinary exchange ideas. In this paper, we a type workshop, called hack week, which allows for fast dissemination methodologies fosters collaboration within between disciplines. We present implementations concept in astronomy, neuroscience, geoscience show...
ABSTRACT We report on exceptionally bright bursts (&gt;400 Jy ms) detected from the repeating fast radio burst source FRB 20220912A using Nançay telescope (NRT), as part of ECLAT (Extragalactic Coherent Light Astrophysical Transients) monitoring campaign. These exhibit extremely luminous, broad-band, short-duration structures (∼16 μs), which we term ‘microshots’ and can be especially well studied in NRT data given excellent signal-to-noise dynamic range (32-bit samples). The estimated...
We present a new observational method to type the explosions of young supernova remnants (SNRs). By measuring morphology Chandra X-ray line emission in seventeen Galactic and Large Magellanic Cloud SNRs with multipole expansion analysis (using power ratios), we find that core-collapse are statistically more asymmetric than Type Ia SNRs. show two classes supernovae can be separated naturally using this technique because morphologies reflect distinct explosion mechanisms structure...
Jets around low- and intermediate-mass young stellar objects (YSOs) contain a fossil record of the recent accretion outflow activity their parent star-forming systems. We aim to understand whether accretion/ejection process is similar across entire mass range YSOs. To this end we have obtained VLT/X-shooter spectra HH 1042 1043, two newly discovered jets in massive region RCW 36. associated with YSO 08576nr292. Over 90 emission lines are detected spectra. High-velocity (up 220 km/s) blue-...
The discovery of quasi-periodic oscillations (QPOs) in magnetar giant flares has opened up prospects for neutron star asteroseismology. scarcity makes a search QPOs the shorter, far more numerous bursts from Soft Gamma Repeaters (SGRs) desirable. In Huppenkothen et al (2013), we developed Bayesian method searching short bursts, taking into account effects complicated burst structure, and have shown its feasibility on small sample bursts. Here, apply same to much larger storm 286 SGR...
ABSTRACT We report on the analysis of two deep XMM-Newton observations magnetar Swift J1834.9−0846 and its surrounding extended emission taken in 2014 March October, 2.5 3.1 yr after source went into outburst. The is only weakly detected first observation, with an absorption-corrected flux <?CDATA ${F}_{0.5-10\mathrm{keV}}\approx 4\times {10}^{-14}$?> erg s −1 cm −2 a $3\sigma $?> upper limit during second observation about 3 × 10 −14 . This level more than orders magnitude lower measured at...
We present Zwicky Transient Facility (ZTF) observations of the tidal disruption flare AT2018zr/PS18kh reported by Holoien et al. and detected during ZTF commissioning. The light curve event (TDE) samples rise-to-peak exceptionally well, with 50 days g- r-band detections before time maximum light. also our multi-wavelength follow-up observations, including detection a thermal (kT~100 eV) X-ray source that is two orders magnitude fainter than contemporaneous optical/UV blackbody luminosity,...
Abstract This paper describes the design and implementation of stingray , a library in Python built to perform time series analysis related tasks on astronomical light curves. Its core functionality comprises range Fourier techniques commonly used spectral-timing analysis, as well extensions for analyzing pulsar data, simulating data sets, statistical modeling. modular build allows easy incorporation its methods into workflows pipelines. We aim be platform future techniques. describe overall...
This paper describes the design and implementation of Stingray, a library in Python built to perform time series analysis related tasks on astronomical light curves. Its core functionality comprises range Fourier techniques commonly used spectral-timing analysis, as well extensions for analyzing pulsar data, simulating data sets, statistical modeling. modular build allows easy incorporation its methods into workflows pipelines. We aim be platform future techniques. Here, we describe overall...
The X-ray Pulse Simulation and Inference (X-PSI) package is a software designed to simulate rotationally-modulated surface emission from neutron stars perform Bayesian statistical inference on real or simulated pulse profile data sets.Model parameters of interest include star mass radius the system geometry properties hot emitting regions.
Quasi-periodic oscillations (QPOs) observed in the giant flares of magnetars are particular interest due to their potential open up a window into neutron star interior via asteroseismology. However, only three have been observed. We therefore make use much larger data set shorter, less energetic recurrent bursts. Here, we report on search for QPOs large bursts from two most burst-active magnetars, SGR 1806–20 and 1900+14, with Rossi X-ray Timing Explorer. find single detection an averaged...
Two energetic hard X-ray bursts have recently triggered the Fermi and Swift space observatories from rotation powered pulsar, PSR J1119-6127. We performed in depth spectral temporal analyses of these two events. Our extensive searches both observatory data for lower luminosity uncovered 10 additional events source. report here on timing energetics 12 J1119-6127 during its burst active phase 2016 July 26 28. also found a softer flux enhancement post episode, which shows evidence cooling....
Relativistic effects dominate the emission of blazar jets complicating our understanding their intrinsic properties. Although many methods have been proposed to account for them, variability Doppler factor method has shown describe populations best. We use a Bayesian hierarchical code called {\it Magnetron} model light curves 1029 sources observed by Owens Valley Radio Observatory's 40-m telescope as series flares with an exponential rise and decay, estimate brightness temperature. Our...
M82 X-2 is the first pulsating ultraluminous X-ray source (PULX) discovered. The luminosity of these extreme pulsars, if isotropic, implies an mass transfer rate. An alternative to assume a much lower rate, but with apparent boosted by geometrical beaming. Only independent measurement rate can help discriminate between two scenarios. In this Paper, we follow orbit neutron star for seven years, measure decay ($\dot{P}_{orb}/{P}_{orb}\approx-8\cdot10^{-6}\mathrm{yr}^{-1}$), and argue that...