A5080647617- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Gamma-ray bursts and supernovae
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Nuclear Physics and Applications
- High-pressure geophysics and materials
- Solar and Space Plasma Dynamics
- Particle Accelerators and Free-Electron Lasers
- Geophysics and Sensor Technology
- Astrophysics and Star Formation Studies
- Advanced X-ray Imaging Techniques
- Relativity and Gravitational Theory
- Fault Detection and Control Systems
- Astro and Planetary Science
- Particle Detector Development and Performance
- Adaptive optics and wavefront sensing
- Radiation Effects and Dosimetry
- Ionosphere and magnetosphere dynamics
- Nuclear reactor physics and engineering
- Catalysis and Oxidation Reactions
- Computational Fluid Dynamics and Aerodynamics
Michigan State University
2016-2022
Columbia University
2020
Time Domain (United States)
2018
We present the results of an ultra-deep, comprehensive radio continuum survey for accretion signatures intermediate-mass black holes in globular clusters. The sample, imaged with Karl G.~Jansky Very Large Array and Australia Telescope Compact Array, comprises 50 Galactic No compelling evidence hole is found any cluster our sample. In order to achieve highest sensitivity low-level emission, we also overall stack as well various subsamples, finding non-detections. These strengthen idea that...
We present the first optical spectroscopy of five confirmed (or strong candidate) redback millisecond pulsar binaries, obtaining complete radial velocity curves for each companion star. The properties these binaries with low-mass, hydrogen-rich companions are discussed in context 14 and 10 candidate field redbacks. find that neutron stars redbacks have a median mass 1.78 +/- 0.09 M_sun dispersion sigma = 0.21 0.09. Neutron masses excess 2 consistent with, but not firmly demanded by, current...
Abstract The physical mechanism driving mass ejection during a nova eruption is still poorly understood. Possibilities include in single ballistic event, common-envelope interaction, continuous wind, or some combination of these processes. Here, we present study 12 Galactic novae, for which have premaximum high-resolution spectroscopy. All novae show the same spectral evolution. Before optical peak, they slow P Cygni component. After fast component quickly arises, while absorption remains...
Abstract We present the discovery and characterization of a radio-bright binary in Galactic globular cluster M10. First identified deep radio continuum data from Karl G. Jansky Very Large Array, M10-VLA1 has flux density 27 ± 4 μ Jy at 7.4 GHz flat-to-inverted spectrum. Chandra imaging shows an X-ray source with L X ≈ 10 31 erg s −1 matching location source. This places within scatter radio-X-ray luminosity correlation for quiescent stellar-mass black holes, hole is viable explanation this...
We report the discovery of an eclipsing low-mass X-ray binary at center 3FGL error ellipse unassociated Fermi/Large Area Telescope gamma-ray source J0427.9-6704. Photometry from OGLE and SMARTS 1.3-m telescope spectroscopy SOAR have allowed us to classify system as (P = 8.8 hr) with a main sequence donor neutron star accretor. Broad double-peaked H He emission lines suggest ongoing presence accretion disk. Remarkably, shows separate sets absorption associated disk secondary, we use their...
Abstract Globular clusters host a variety of lower-luminosity ( L X < 10 35 erg s −1 ) X-ray sources, including accreting neutron stars (NSs) and black holes (BHs), millisecond pulsars (MSPs), cataclysmic variables, chromospherically active binaries. In this paper, we provide comprehensive catalog more than 1100 sources in 38 Galactic globular (GCs) observed by the Chandra Observatory’s Chandra/ACIS detector. The targets are selected to complement MAVERIC survey’s deep radio continuum...
The Fermi $\gamma$-ray source 1FGL J1417.7--4407 (J1417) is a compact X-ray binary with neutron star primary and red giant companion in $\sim$5.4 day orbit. This initial conclusion, based on optical data, was confirmed when 2.66 ms radio pulsar found at the same location (and orbital properties) as optical/X-ray source. However, these studies conflicting evidence about accretion state other properties of binary. We present new optical, radio, observations J1417 that allow us to better...
We characterize the extreme heartbeat star system MACHO 80.7443.1718 in LMC using TESS photometry and spectroscopic observations from Magellan Inamori Kyocera Echelle (MIKE) SOAR Goodman spectographs. was first identified as a All-Sky Automated Survey for SuperNovae (ASAS-SN) with $P_{\rm orb}=32.836\pm0.008\,{\rm d}$. is young (${\sim}6$~Myr), massive binary, composed of B0 Iae supergiant $M_1 \simeq 35 M_\odot$ an O9.5V secondary $M_2 16 on eccentric ($e=0.51\pm0.03$) orbit. In addition to...
Abstract We present optical photometric and spectroscopic observations of the likely stellar counterpart to unassociated Fermi Large Area Telescope (LAT) γ -ray source 2FGL J0846.0+2820, selected for study based on positional coincidences variables with LAT sources. Using spectroscopy from SOAR telescope, we have identified a late-G giant in an eccentric ( e = 0.06) 8.133-day orbit invisible primary. Modeling photometry together led us infer heavy neutron star primary <?CDATA $\sim...
ABSTRACT Using a 16.2-h radio observation by the Australia Telescope Compact Array and archival Chandra data, we found &gt;5σ counterparts to four known three new X-ray sources within half-light radius (rh) of Galactic globular cluster NGC 6397. The previously suggested millisecond pulsar (MSP) candidate, U18, is steep-spectrum (Sν ∝ να; $\alpha =-2.0^{+0.4}_{-0.5}$) source with 5.5-GHz flux density 54.7 ± 4.3 $\mu \mathrm{ Jy}$. We argue that U18 most likely ‘hidden’ MSP continuously...
We report the discovery of a variable optical and X-ray source within error ellipse previously unassociated Fermi Large Area Telescope $\gamma$-ray 4FGL J0407.7--5702. A 22 ksec observation from XMM-Newton/EPIC shows an light curve with rapid variability flaring. The spectrum is well-fit by hard power law $\Gamma = 1.7$. Optical photometry taken over several epochs dominated aperiodic variations moderate amplitude. spectroscopy SOAR Gemini reveals blue continuum broad double-peaked H He...
Transitional millisecond pulsars are that switch between a rotation-powered pulsar state and an accretion-powered X-ray binary state, thought to be evolutionary stage neutron star low-mass binaries pulsars. So far, only three confirmed systems have been identified in addition handful of candidates. We present the results multi-wavelength study NGC 6652B globular cluster 6652, including simultaneous radio observations taken by Karl G. Jansky Very Large Array Chandra Observatory, optical...
Transitional millisecond pulsars are accreting that switch between X-ray binary and radio pulsar states. Only a handful of these objects have been identified so far. Terzan 5 CX1 is variable hard source in the globular cluster 5. In this paper, we identify counterpart to deep Very Large Array continuum data. Chandra observations over last fourteen years indicate shows two brightness states: 2003 2016 was brightest (at L$_X \sim 10^{33}$ erg s$^{-1}$), while many intermediate observations,...
Owing to its massive, dense core, Terzan 5 has the richest population of millisecond pulsars known among Galactic globular clusters. Here we report new deep $2-8\,$GHz radio continuum observations Terzan\,5 obtained with Karl G. Jansky Very Large Array. We have identified a total 24 sources within cluster half-light radius, including 17 core radius. 19 are associated previously studied and X-ray binaries. Three steep spectra located as expected for pulsars. These three hard photon indices...
Abstract PSR J1306–40 is a millisecond pulsar (MSP) binary with non-degenerate companion in an unusually long ∼1.097 day orbit. We present new optical photometry and spectroscopy of this system, model these data to constrain fundamental properties the such as component masses distance. The imply minimum neutron star mass 1.75 ± 0.09 M ⊙ (1 σ ) high, nearly edge-on inclination. light curves suggest large hot spot on companion, suggestive portion wind being channeled stellar surface by...
Abstract The MAVERIC survey is the first deep radio continuum imaging of Milky Way globular clusters, with a central goal finding and classifying accreting compact binaries, including stellar-mass black holes. Here we present source catalogs for 25 clusters ultra-deep Karl G. Jansky Very Large Array observations. median observing time was 10 hr per cluster, resulting in typical rms sensitivities 2.3 2.1 μ Jy beam at frequencies 5.0 7.2 GHz, respectively. We detect nearly 1300 sources our 5 σ...
Abstract Accreting neutron stars in low-mass X-ray binaries show outflows—and sometimes jets—in the general manner of accreting black holes. However, quantitative link between accretion flow (traced by X-rays) and outflows and/or jets radio emission) is much less well understood for than holes, other observation that are fainter at a given luminosity. We use data from deep MAVERIC continuum survey Galactic globular clusters systematic study six luminous ( L X > 10 34 erg s −1 ) persistent...
The nature of very faint X-ray transients (VFXTs) - transient sources that peak at luminosities $L_X\lesssim10^{36} {\rm erg s^{-1}}$ is poorly understood. and often short-lived outbursts make characterising VFXTs their multi-wavelength counterparts difficult. In 2017 April we initiated the Swift Bulge Survey, a shallow survey $\sim$16 square degrees around Galactic centre with Neil Gehrels Observatory. has been designed to detect new known VFXTs, follow-up programmes arranged study...
We present a deep ($\sim 330~\mathrm{ks}$) {\it Chandra} survey of the Galactic globular cluster M30 (NGC 7099). Combining new Cycle 18 with previous 3 observations we report total 10 X-ray point sources within $1.03$ arcmin half-light radius, compiling an extended catalogue 23 sources. incorporate imaging by Hubble Space Telescope} and Karl G. Jansky Very Large Array} from MAVERIC to search for optical radio counterparts old Two are found have counterpart, including known millisecond pulsar...
ABSTRACT Radio continuum observations offer a new window on compact objects in globular clusters compared to typical X-ray or optical studies. As part of the MAVERIC survey, we have used Australia Telescope Compact Array carry out deep (median central noise level ≈4 $\mu$Jy beam-1) radio survey 26 southern at frequencies 5.5 and 9.0 GHz. This paper presents catalogue 1285 sources fields these clusters. Considering surface density background sources, find significant evidence for population...
Abstract We present the discovery of a likely new redback millisecond pulsar (MSP) binary associated with Fermi γ -ray source 4FGL J2333.1–5527. Using optical photometric and spectroscopic observations from Southern Astrophysical Research telescope, we identify low-mass, main-sequence-like companion in 6.9 hr, highly inclined orbit around suspected massive neutron star primary. Archival XMM-Newton X-ray show this system has hard power-law spectrum Γ = 1.6 ± 0.3 L X ∼ 5 × 10 31 erg s −1 ,...
Abstract We report the discovery of 1RXH J082623.6−505741, a 10.4 hr orbital period compact binary. Modeling extensive optical photometry and spectroscopy reveals ∼0.4 M ⊙ K-type secondary transferring mass through low-state accretion disk to nonmagnetic ∼0.8 white dwarf. The is overluminous for its dominates spectra at all epochs must be evolved fill Roche Lobe this period. X-ray luminosity L X ∼ 1–2 × 10 32 erg s −1 derived from both new XMM-Newton archival observations, although high...
We present a detailed study of the 2017 eruption classical nova ASASSN-17pf (LMCN 2017-11a), which is located in Large Magellanic Cloud, including data from AAVSO, ASAS-SN, SALT, SMARTS, SOAR, and Neil Gehrels \textit{Swift} Observatory. The optical light-curve characterized by multiple maxima (flares) on top slowly evolving (with decline time, $t_2>$ 100 d). correlate with appearance new absorption line systems spectra increasing radial velocities. suggest that this evidence episodes...
Abstract We report on X-ray and radio observations of the ultra-compact binary 4U 1543−624 taken in August 2017 during an enhanced accretion episode. obtained Neutron Star Interior Composition Explorer ( NICER ) monitoring source over a ∼10 day period which target-of-opportunity were also conducted with Swift , INTErnational Gamma-Ray Astrophysics Laboratory INTEGRAL ), Australia Telescope Compact Array. Emission lines measured spectrum at ∼0.64 keV ∼6.4 that correspond to O Fe,...