A5070948049- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Geophysics and Gravity Measurements
- Cosmology and Gravitation Theories
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- Stellar, planetary, and galactic studies
- Astronomical Observations and Instrumentation
- Black Holes and Theoretical Physics
- Radio Astronomy Observations and Technology
- Astronomy and Astrophysical Research
- Atomic and Subatomic Physics Research
- Seismic Waves and Analysis
- Statistical and numerical algorithms
- Computational Physics and Python Applications
- Adaptive optics and wavefront sensing
- Particle physics theoretical and experimental studies
- earthquake and tectonic studies
- Dark Matter and Cosmic Phenomena
- Astro and Planetary Science
- Relativity and Gravitational Theory
- Mechanics and Biomechanics Studies
- Astrophysics and Star Formation Studies
- Geophysics and Sensor Technology
Northwestern University
2021-2024
University of Oregon
2020-2023
University of Chicago
2016-2022
Fermi National Accelerator Laboratory
2020
We present UV, optical, and NIR photometry of the first electromagnetic counterpart to a gravitational wave source from Advanced LIGO/Virgo, binary neutron star merger GW170817. Our data set extends discovery optical at $0.47$ days $18.5$ post-merger, includes observations with Dark Energy Camera (DECam), Gemini-South/FLAMINGOS-2 (GS/F2), {\it Hubble Space Telescope} ({\it HST}). The spectral energy distribution (SED) inferred this $0.6$ is well described by blackbody model $T\approx 8300$...
Abstract We present the Dark Energy Camera (DECam) discovery of optical counterpart first binary neutron star merger detected through gravitational-wave emission, GW170817. Our observations commenced 10.5 hr post-merger, as soon localization region became accessible from Chile. imaged 70 deg 2 in i and z bands, covering 93% initial integrated probability, to a depth necessary identify likely counterparts (e.g., kilonova). At 11.4 post-merger we bright transient located nucleus NGC 4993 at...
We report the discovery of rising X-ray emission from binary neutron star (BNS) merger event GW170817. This is first detection a gravitational-wave source. Observations acquired with Chandra Observatory (CXO) at t~2.3 days post reveal no significant emission, L_x<=3.2x10^38 erg/s (isotropic-equivalent). Continued monitoring revealed presence an source that brightened time, reaching L_x\sim 9x10^39 ~15.1 merger. interpret these findings in context isotropic and collimated relativistic...
All ten LIGO/Virgo binary black hole (BH-BH) coalescences reported following the O1/O2 runs have near-zero effective spins. There are only three potential explanations for this. If BH spin magnitudes large, then: (i) either both vectors must be nearly in orbital plane or (ii) angular momenta of BHs oppositely directed and similar magnitude. Then there is also possibility that (iii) small. We consider third hypothesis within framework classical isolated evolution scenario BH-BH merger...
The detection of the binary neutron star GW170817 together with observation electromagnetic counterparts across entire spectrum inaugurated a new era multi-messenger astronomy. In this study we incorporate wavelength-dependent opacities and emissivities calculated from atomic-structure data enabling us to model both measured lightcurves spectra transient AT2017gfo. Best-fits observational are obtained by Gaussian Process Regression, which allows present posterior samples for kilonova source...
Abstract We introduce the first complete nonparametric model for astrophysical distribution of binary black hole (BBH) population. Constructed from basis splines, we use these models to conduct most comprehensive data-driven investigation BBH population date, simultaneously fitting mass ratio, spin magnitude and misalignment, redshift distributions. With GWTC-3, report same features previously recovered with similarly flexible distribution, notably peaks in merger rates at primary masses ∼10...
We present the properties of NGC 4993, host galaxy GW170817, first gravitational wave (GW) event from merger a binary neutron star (BNS) system and with an electromagnetic (EM) counterpart. use both archival photometry new optical/near-IR imaging spectroscopy, together stellar population synthesis models to infer global galaxy. formation history peaked at $\gtrsim 10$ Gyr ago, subsequent exponential decline leading low current rate 0.01 M$_{\odot}$ yr$^{-1}$, which we convert into timescale...
We present a comprehensive comparison of the properties radio through X-ray counterpart GW170817 and short-duration gamma-ray bursts (GRBs). For this effort, we utilize sample 36 short GRBs spanning redshift range $z \approx 0.12-2.6$ discovered over 2004-2017. find that to has an isotropic-equivalent luminosity is $\approx 3000$ times less than median value on-axis GRB afterglows, $\gtrsim10^{4}$ for detected afterglows. Moreover, allowed jet energies particle densities inferred from...
Abstract We present a multi-messenger measurement of the Hubble constant H 0 using binary–black-hole merger GW170814 as standard siren, combined with photometric redshift catalog from Dark Energy Survey (DES). The luminosity distance is obtained gravitational wave signal detected by Laser Interferometer Gravitational-Wave Observatory (LIGO)/Virgo Collaboration (LVC) on 2017 August 14, and information provided DES Year 3 data. Black hole mergers such are expected to lack bright...
The Large Synoptic Survey Telescope is designed to provide an unprecedented optical imaging dataset that will support investigations of our Solar System, Galaxy and Universe, across half the sky over ten years repeated observation. However, exactly how LSST observations be taken (the observing strategy or "cadence") not yet finalized. In this dynamically-evolving community white paper, we explore detailed performance anticipated science expected depend on small changes strategy. Using...
Data from the LIGO and Virgo detectors has confirmed that stellar-mass black holes can merge within a Hubble time, leaving behind massive remnant holes. In some astrophysical environments such as globular clusters AGN disks, it may be possible for these remnants to take part in further compact-object mergers, producing population of hierarchically formed this work, we present parameterized framework describing binary hole while self-consistently accounting hierarchical mergers. The casts...
We study the evolution of binary black hole (BBH) mass distribution across cosmic time. The second gravitational-wave transient catalog (GWTC-2) from LIGO/Virgo contains BBH events out to redshifts $z \sim 1$, with component masses in range $\sim5$--$80\,M_\odot$. In this catalog, biggest holes, $m_1 \gtrsim 45\,M_\odot$, are only found at highest redshifts, 0.4$. ask whether absence high-mass observations low redshift indicates that astrophysical evolves: BBHs merge high redshift, and cease...
We introduce a semi-parametric model for the primary mass distribution of binary black holes (BBHs) observed with gravitational waves (GWs) that applies cubic-spline perturbation to power law. apply this 46 BBHs included in second wave transient catalog (GWTC-2). The spline recovers consistent previous results, corroborating existence peak at $35\,M_\odot$ ($>97\%$ credibility) found \textsc{Powerlaw+Peak} model. could be result pulsational pair-instability supernovae (PPISNe). finds...
ABSTRACT We report the results of a deep search for an optical counterpart to gravitational wave (GW) event GW150914, first trigger from Advanced LIGO GW detectors. used Dark Energy Camera (DECam) image 102 deg 2 area, corresponding 38% initial high-probability sky region and 11% revised region. observed in i z bands at 4–5, 7, 24 days after trigger. The median 5 σ point-source limiting magnitudes our images are = 22.5 21.8 mag. processed through difference-imaging pipeline using templates...
We report the results of a Dark Energy Camera (DECam) optical follow-up gravitational wave (GW) event GW151226, discovered by Advanced LIGO detectors. Our observations cover 28.8 deg$^2$ localization region in $i$ and $z$ bands (containing 3% BAYESTAR probability), starting 10 hours after was announced spanning four epochs at $2-24$ days GW detection. achieve $5\sigma$ point-source limiting magnitudes $i\approx21.7$ $z\approx21.5$, with scatter $0.4$ mag, our difference images. Given two day...
Models of gravitational waveforms play a critical role in detecting and characterizing the waves (GWs) from compact binary coalescences. Waveforms numerical relativity (NR), while highly accurate, are too computationally expensive to produce be directly used with Bayesian parameter estimation tools like Markov-chain-Monte-Carlo nested sampling. We propose Gaussian process regression (GPR) method generate accurate reduced-order-model based only on existing (e.g. NR) simulations. Using...
There are few observed high-mass X-ray binaries (HMXBs) that harbor massive black holes, and none likely to result in a binary hole (BBH) merges within Hubble time; however, we know merging BBHs exist from gravitational-wave observations. We investigate the role observational selection effects play determining properties of their respective detected populations. find that, as effects, detectable HMXBs form at different redshifts metallicities, with forming much lower higher metallicities...
Abstract Wind Roche-lobe overflow (WRLOF) is a mass-transfer mechanism proposed by Mohamed and Podsiadlowski for stellar binaries wherein the wind acceleration zone of donor star exceeds its radius, allowing material to be transferred accretor at enhanced rates. WRLOF may explain characteristics observed in blue lurkers stragglers. While has been implemented rapid population synthesis codes, it yet explored thoroughly detailed binary models such as MESA (a 1D evolution code), over wide range...
Stellar evolution models predict the existence of a gap in black hole mass spectrum from $\sim55 M_\odot - 120 M_\odot$ due to pair-instability supernovae (PISNe). We investigate possible such an "upper" second gravitational wave transient catalog (GWTC-2) by hierarchically modeling astrophysical distribution masses. extend Truncated and Powerlaw+Peak families allow for explicit distribution, apply extended GWTC-2. find that with model there is mild evidence favoring upper log Bayes Factor...
The inspiral and merger of two black holes produces a remnant hole with mass spin determined by the properties its parent holes. Using inferred population component from first half observing runs Advanced LIGO Virgo, we calculate leftover By integrating their rate formation over age universe, estimate number density today. simple prescriptions for cosmic star delay times, determine this to be $660_{-240}^{+440} \mathrm{Mpc}^{-3}$, corresponding $\sim 60,000$ remnants per Milky-Way-equivalent...
The LIGO-Virgo-KAGRA (LVK) Collaboration has reported nearly 100 BH-BH mergers. LVK provides estimates of rates, masses, effective spins, and redshifts for these Yet, the formation channel(s) mergers remains uncertain. One way to search a site is contrast properties detected with different models merger formation. Our study designed investigate usefulness total mass its evolution redshift in establishing origin gravitational-wave sources. We find that average intrinsic shows exceptionally...
Gravitational-wave observations of binary black hole (BBH) systems point to spin magnitudes being relatively low. These measurements appear in tension with high for high-mass X-ray binaries (HMXBs). We use grids MESA simulations combined the rapid population-synthesis code COSMIC examine origin these two populations. It has been suggested that Case-A mass transfer while both stars are on main sequence can form high-spin BHs HMXBs. Assuming this formation channel, we show depending critical...