A5008714597- Astrophysical Phenomena and Observations
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Gamma-ray bursts and supernovae
- Pulsars and Gravitational Waves Research
- Astrophysics and Star Formation Studies
- Adaptive optics and wavefront sensing
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- High-pressure geophysics and materials
- History and Developments in Astronomy
- Organic Chemistry Synthesis Methods
- Scientific Measurement and Uncertainty Evaluation
- Calibration and Measurement Techniques
- Classical Philosophy and Thought
- Relativity and Gravitational Theory
- Statistical and numerical algorithms
- Particle Accelerators and Free-Electron Lasers
- Plant-based Medicinal Research
- Mechanics and Biomechanics Studies
- Astro and Planetary Science
- Nuclear physics research studies
- Advanced Frequency and Time Standards
- Laser-Plasma Interactions and Diagnostics
Space Telescope Science Institute
2016-2025
Naval Postgraduate School
2024
Michigan State University
2016-2019
Texas Tech University
2014-2019
Louisiana State University
2011-2017
University of Alberta
2016
SRON Netherlands Institute for Space Research
2016
Radboud University Nijmegen
2016
University of Michigan
2016
University of Warwick
2016
Abstract This paper characterizes the actual science performance of James Webb Space Telescope (JWST), as determined from six month commissioning period. We summarize spacecraft, telescope, instruments, and ground system, with an emphasis on differences pre-launch expectations. Commissioning has made clear that JWST is fully capable achieving discoveries for which it was built. Moreover, almost across board, better than expected; in most cases, will go deeper faster expected. The telescope...
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 We present mid-infrared (MIR) spectral-timing measurements of the prototypical Galactic microquasar GRS 1915+105. The source was observed with Mid-Infrared Instrument (MIRI) onboard JWST in June 2023 at a MIR luminosity LMIR ≈ 1036 erg s−1 exceeding past IR levels by about factor 10. In contrast, X-ray flux is much fainter than historical average, source’s now–persistent ‘obscured’ state. MIRI low-resolution spectrum shows plethora emission lines, strongest which are consistent...
We introduce the Galactic Bulge Survey (GBS) and we provide Chandra source list for region that has been observed to date. Among goals of GBS are constraining neutron star (NS) equation state black hole (BH) mass distribution via identification eclipsing NS BH low-mass X-ray binaries (LMXBs). The latter goal will, in addition, be obtained by significantly enlarging number systems which a can derived. Further include binary formation scenarios, particular common envelope phase occurrence...
Abstract We present the first Data Release (DR1) from Hubble Space Telescope (HST) Ultraviolet Legacy Library of Young Stars as Essential Standards (ULLYSES) program, a Director’s Discretionary program devoting approximately 1000 HST orbits to production an ultraviolet spectroscopic library young high- and low-mass stars in local universe. The science products this release are combined individual, extracted calibrated spectra obtained with COS STIS instruments aboard HST. Products made using...
This paper characterizes the actual science performance of James Webb Space Telescope (JWST), as determined from six month commissioning period. We summarize spacecraft, telescope, instruments, and ground system, with an emphasis on differences pre-launch expectations. Commissioning has made clear that JWST is fully capable achieving discoveries for which it was built. Moreover, almost across board, better than expected; in most cases, will go deeper faster expected. The telescope instrument...
The Galactic Bulge Survey (GBS) is a wide but shallow X-ray survey of regions above and below the Plane in Bulge. It was performed using Chandra Observatory's ACIS camera. primarily designed to find classify low luminosity binaries. combination depth accessibility optical infrared counterparts makes this ideally suited identification new symbiotic binaries (SyXBs) We consider specific case source CXOGBS J173620.2–293338. coincident within 1 arcsec with very red star, showing carbon star...
We present the orbital solution for donor star of candidate transitional millisecond pulsar 3FGL J1544.6-1125, currently observed as an accreting low-mass X-ray binary. The period is $0.2415361(36)$ days, entirely consistent with spectral classification a mid to late K dwarf. semi-amplitude radial velocity curve exceptionally low at $K_2=39.3\pm1.5$ km s$^{-1}$, implying remarkably face-on inclination in range 5--8$^{\circ}$, depending on neutron and masses. After determining veiling...
We present the identification of optical counterparts to 23 GBS X-ray sources. All sources are classified as accreting binaries according emission-line characteristics inferred from medium-resolution spectroscopy. To distinguish chromospherically active objects, we develop criteria based on Hα and He i λλ5786, 6678 properties available in literature. The spectroscopic photometric variability each object is discussed a classification given where possible. At least 12 systems show an...
We present a new method to derive binary inclinations in quiescent black hole (BH) X-ray transients (XRTs), based on the depth of trough (T) from double-peaked Ha emission profiles arising accretion discs. find that inclination angle (i) is linearly correlated with T phase-averaged spectra sufficient orbital coverage (>~50 per cent) and spectral resolution, following i (deg)=93.5 x +23.7. The correlation caused by combination line opacity local broadening, where leading (excess broadening)...
We present optical light curves, spectroscopy, and classification of five X-ray sources in the Chandra Galactic Bulge Survey (CXOGBS J174009.1−284725 (CX5), CXOGBS J173935.7−272935 (CX18), J173946.9−271809 (CX28), J173729.1−292804 (CX37), J174607.6−261547 (CX561)). These objects were selected based on bright counterparts which quickly found to have emission lines their spectra. This paper presents an illustration GBS follow-up, targeting line objects. Of these objects, four exhibit...
We discuss radio sources in the Chandra Galactic Bulge Survey region. By cross-matching X-ray this field with NRAO VLA Sky archival data, we find 12 candidate matches. present a classification scheme for radio/X-ray matches surveys taken or near plane, taking into account other multiwavelength data. show that none of found here is likely to be due coronal activity from normal stars because flux ratios are systematically too high. one source could pulsar, and planetary nebula, but bulk...
We provide the Chandra source list for last ∼quarter of area covered by Galactic Bulge Survey (GBS). The GBS targets two strips 6° × 1° (12 square degrees in total), one above (1° < b 2°) and below (−2° −1°) plane direction center at X-ray, optical, near-infrared wavelengths. For X-ray part survey we use 2 ks per pointing. find 424 sources 63 observations on which report here. These are addition to 1216 discovered first described previously. discuss characteristics variability brightest as...
We report on the discovery of a hydrogen-deficient compact binary (CXOGBS J175107.6-294037) belonging to AM CVn class in Galactic Bulge Survey. Deep archival X-ray observations constrain positional uncertainty source 0.57 arcsec, and allow us uniquely identify optical UV counterpart. Optical spectroscopic reveal presence broad, shallow He i absorption lines while no sign hydrogen is present, consistent with high state system. present lightcurve from Gravitational Lensing Experiment...
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...
We measure the duty cycles for an existing sample of well observed, nearby dwarf novae using data from AAVSO, and present a quantitative empirical relation between cycle outbursts X-ray luminosity system in quiescence. have found that $\log DC=0.63(\pm0.21)\times(\log L_{X}({\rm erg\,s^{-1}})-31.3)-0.95(\pm0.1)$, where DC stands cycle. note there is intrinsic scatter this greater than what expected purely statistical errors. Using nova functions \citet{Pretorius12} \citet{Byckling10}, we...
To confirm the nature of donor star in ultra-compact X-ray binary candidate 47 Tuc X9, we obtained optical spectra (3,000$-$10,000 {\AA}) with Hubble Space Telescope / Imaging Spectrograph. We find no strong emission or absorption features spectrum X9. In particular, place $3\sigma$ upper limits on H$\alpha$ and HeII $\lambda 4686$ line equivalent widths $-$EW$_{\mathrm{H\alpha}} \lesssim 14$ {\AA} $-$EW$_{\mathrm{HeII}} 9$ {\AA}, respectively. This is much lower than seen for typical...
We present the results of a photometric and spectroscopic analysis Galactic Bulge Survey X-ray source CXOGBS J174954.5-294335 (hereafter, referred to as CX19). CX19 is long period, eclipsing intermediate polar type cataclysmic variable with broad, single-peaked Balmer Paschen emission lines along HeII $\lambda4686$ Bowen blend features. With coverage one full two partial eclipses archival photometry, we determine ephemeris for be HJD(eclipse) = 2455691.8581(5) + 0.358704(2)$\times$N. also...
We present optical lightcurves of variable stars consistent with the positions X-ray sources identified Chandra Observatory for Galactic Bulge Survey. Using data from Mosaic-II instrument on Blanco 4m Telescope at CTIO, we gathered time-resolved photometric timescales $\sim2$ hr to 8 days over $\frac{3}{4}$ survey containing initial GBS catalog. Among lightcurve morphologies identify are flickering in interacting binaries, eclipsing sources, dwarf nova outbursts, ellipsoidal variations, long...
We report on multi-wavelength observations during quiescence and of the first detected outburst ~60 min orbital period AM CVn SDSS J113732+405458. Using X-ray UV we determined an upper limit duration event about one year. The amplitude was remarkably small, around magnitude in r 0.5 magnitudes g. have also investigated color variations J113732+405458 other long CVns outbursts identified a track color-magnitude diagram that is not compatible with predictions disk instability model, suggesting...
We present phase-resolved spectroscopy and photometry of a source discovered with the Chandra Galactic Bulge Survey (GBS), CXOGBS J174444.7−260330 (aka CX93 CX153 in previously published GBS list). find two possible values for orbital period P, differing from each other by ∼13 s. The most likely solution is P = 5.690 14(6) h. optical lightcurves show ellipsoidal modulations, whose modelling provides an inclination 32±1° P. spectra are dominated K5 V companion star (the disc veiling ≲5 per...
We identify 69 X-ray sources discovered by the Galactic Bulge Survey (GBS) that are coincident with, or very close to bright stars in Tycho-2 catalog. Additionally, two other GBS resolved binary companions where both components separately detected X-rays. Most of these likely be real matches, but we nine objects with large and significant optical offsets as either detections chance alignments. collate known spectral types for objects, also examine 2MASS colors, variability information from...
As part of the Chandra Galactic Bulge Survey (GBS), we present a catalogue optical sources in GBS footprint. This consists two regions centered at latitude b = 1.5 degrees above and below Centre, spanning (l x b) (6x1) degrees. The 2 or more epochs observations for each line sight r', i' H{\alpha} filters. It is complete down to r' 20.2 19.2 mag; mean 5{\sigma} depth 22.5 21.1 mag. root-mean-square residuals astrometric solutions 0.04 arcsec. We cross-correlate this with 1640 unique X-ray...
Abstract JWST, despite not being designed to observe astrophysical phenomena that vary on rapid timescales, can be an unparalleled tool for such studies. If timing systematics controlled, JWST will able open up the subsecond infrared timescale regime. Rapid time-domain studies, as lag measurements in accreting compact objects and solar system stellar occultations, require both precise interframe knowing when a time series begins, down absolute accuracy significantly below 1 s. In this work,...
We report on the near-infrared matches, drawn from three surveys, to 1640 unique X-ray sources detected by Chandra in Galactic Bulge Survey (GBS). This survey targets faint bulge, with a particular focus accreting compact objects. present all viable counterpart candidates and associate false alarm probability (FAP) each match order identify most likely counterparts. The FAP takes into account statistical study involving chance alignment test, as well considering positional accuracy of...