A5079093297- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Astrophysics and Cosmic Phenomena
- Galaxies: Formation, Evolution, Phenomena
- Stellar, planetary, and galactic studies
- Particle Detector Development and Performance
- Geophysics and Gravity Measurements
- Solar and Space Plasma Dynamics
- Astro and Planetary Science
- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray Imaging Techniques
- Mechanics and Biomechanics Studies
- Adaptive optics and wavefront sensing
- Relativity and Gravitational Theory
- High-pressure geophysics and materials
- Nuclear Physics and Applications
- Advanced Semiconductor Detectors and Materials
- Advanced X-ray and CT Imaging
- Spacecraft and Cryogenic Technologies
- Superconducting Materials and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Cosmology and Gravitation Theories
California Institute of Technology
2011-2024
Marshall Space Flight Center
2014
We present a comprehensive sample of all gamma-ray burst (GRB) afterglows with known distances, and we derive their conical opening angles based on observed broadband breaks in light curves. Within the framework this jet model, correct for geometry find that energy release is narrowly clustered around 5 × 1050 ergs. draw three conclusions. First, central engines GRBs energies are comparable to ordinary supernovae. Second, broad distribution fluence luminosity largely result wide variation...
Merging neutron stars offer an exquisite laboratory for simultaneously studying strong-field gravity and matter in extreme environments. We establish the physical association of electromagnetic counterpart EM170817 to gravitational waves (GW170817) detected from merging stars. By synthesizing a panchromatic dataset, we demonstrate that are long-sought production site forging heavy elements by r-process nucleosynthesis. The weak gamma-rays seen dissimilar classical short gamma-ray bursts with...
With the first direct detection of merging black holes in 2015, era gravitational wave (GW) astrophysics began. A complete picture compact object mergers, however, requires an electromagnetic (EM) counterpart. We report ultraviolet (UV) and X-ray observations by Swift Nuclear Spectroscopic Telescope ARray (NuSTAR) EM counterpart binary neutron star merger GW170817. The bright, rapidly fading emission indicates a high mass ($\approx0.03$ solar masses) wind-driven outflow with moderate...
Mergers of galaxies are thought to cause significant gas inflows the inner parsecs, which can activate rapid accretion on supermassive black holes (SMBHs), giving rise active galactic nuclei (AGN). During a fraction this process, SMBHs predicted be enshrouded by and dust. Studying 52 in infrared-selected local luminous ultraluminous infrared different merger stages hard X-ray band, where radiation is less affected absorption, we find that amount material around increases during last phases...
Abstract We present the active galactic nucleus (AGN) catalog and optical spectroscopy for second data release of Swift BAT AGN Spectroscopic Survey (BASS DR2). With this DR2 we provide 1449 spectra, which 1182 are released first time, 858 hard-X-ray-selected AGNs in 70-month sample. The majority spectra (801/1449, 55%) newly obtained from Very Large Telescope (VLT)/X-shooter or Palomar/Doublespec. Many have both higher resolution ( R > 2500, N ∼ 450) and/or very wide wavelength coverage...
We employ a fireball model of the gamma-ray burst (GRB) explosion to constrain intrinsic and environmental parameters four events with good broadband afterglow data: GRB 970508, 980329, 980703, 000926. Using standard assumptions constant circumburst density no evolution fraction energy in postshock magnetic field, we investigate uniformity derived shock physics among these events. find variety parameters: densities that range from those interstellar mediumto diffuse clouds, energies...
We have converted the Palomar 60 inch (1.52 m) telescope from a classic night‐assistant‐operated to fully robotic facility. The automated system, which has been operational since 2004 September, is designed for moderately fast (t≲3 minutes) and sustained (R≲23 mag) observations of gamma‐ray burst afterglows other transient events. Routine queue‐scheduled can be interrupted in response electronic notification An pipeline reduces data real time, then stored on searchable Web‐based archive ease...
We present broadband (radio, optical, and X-ray) light curves spectra of the afterglows four long-duration gamma-ray bursts (GRBs; GRBs 090323, 090328, 090902B, 090926A) detected by Gamma-Ray Burst Monitor Large Area Telescope (LAT) instruments on Fermi satellite. With its wide spectral bandpass, extending to GeV energies, is sensitive with very large isotropic energy releases (1054 erg). Although rare, these events are particularly important for testing GRB central-engine models. When...
Abstract We present measurements of broad emission lines and virial estimates supermassive black hole masses ( M BH ) for a large sample ultrahard X-ray-selected active galactic nuclei (AGNs) as part the second data release BAT AGN Spectroscopic Survey (BASS/DR2). Our catalog includes total 689 AGNs, determined from H α , β Mg ii λ 2798, and/or C iv 1549 lines. The core 512 AGNs drawn 70 month Swift/BAT all-sky catalog. also provide 177 additional that are deeper survey data. study links...
We present NuSTAR observations of the nearby SN 2023ixf in M101 (d=6.9 Mpc) which provide earliest hard X-ray detection a non-relativistic stellar explosion to date at $\delta t\approx$4-d and t\approx$11-d. The spectra are well described by hot thermal bremsstrahlung continuum with $T>25 \rm{keV}$ shining through thick neutral medium hydrogen column that decreases time (initial $N_{\rm{Hint}}=2.6\times 10^{23} \rm{cm^{-2}}$). A prominent Fe K$\alpha$ emission line is clearly detected,...
Abstract AT2022cmc was recently reported as the first on-axis jetted tidal disruption event (TDE) discovered in last decade, and fourth TDE candidate known so far. In this work, we present NuSTAR hard X-ray (3–30 keV) observations of AT2022cmc, well soft (0.3–6 obtained by NICER, Swift, XMM-Newton. Our analysis reveals that broadband spectra can be described a broken power law with f ν ∝ −0.5 ( −1 ) below (above) rest-frame break energy E bk ∼ 10 keV at observer frame t obs = 7.8 17.6 days...
Ever since the discovery of first active galactic nuclei (AGN), substantial observational and theoretical effort has been invested into understanding how massive black holes have evolved across cosmic time. Circum-nuclear obscuration is now established as a crucial component, with almost every AGN observed known to display signatures some level in their X-ray spectra. However, despite more than six decades effort, open questions remain: does accretion power impact structure circum-nuclear...
We report on observations of a type II quasar at redshift z = 3.288, identified as hard X-ray source in 185 ks observation with the Chandra X-Ray Observatory and high-redshift photometric candidate from deep, multiband optical imaging. CXO J084837.9+445352 (hereafter 52) shows an unusually spectrum which we infer absorbing column density NH (4.8 ± 2.1) × 1023 cm-2 (90% confidence) implied unabsorbed 2-10 keV rest-frame luminosity L2-10 3.3 1044 ergs s-1, well within regime. Hubble Space...
Plates of the piezoelectric ceramic lead zirconate titanate thickness approximately 150 mu m adhesively bonded to beryllium copper plates comparable form so-called bimorph elements. The electromechanical behaviour such elements is studied under quasistatic conditions. Features dealt with include electrical poling, hysteresis behaviour, transverse and longitudinal mechanical strain. A theoretical treatment given used interpret measurements.
We present multicolor optical observations of long-duration γ-ray bursts (GRBs) made over a three-year period with the robotic Palomar 60 inch telescope (P60). Our sample consists all 29 events discovered by Swift for which P60 began less than 1 hr after burst trigger. were able to recover 80% afterglows from this prompt sample, and we attribute high efficiency our red coverage. Like Melandri et al. (2008), find that significant fraction (≈50%) show suppression flux regard X-ray emission...
On 2006 May 5, a 4 s duration, low-energy, ~1049 erg, gamma-ray burst (GRB) was observed, spatially associated with z = 0.0894 galaxy. Here we report the discovery of GRB optical afterglow and observations its environment using Gemini South, Hubble Space Telescope (HST), Chandra, Swift, Very Large Array. The this is prominent star-forming region in Sc-type galaxy 2dFGRS S173Z112. Its proximity to suggests that progenitor delay time, from birth explosion, smaller than ~10 Myr. Our HST deep...
Long-duration gamma-ray bursts (GRBs) are widely believed to be highly-collimated explosions (opening angle theta ~ 1-10 deg). As a result of this beaming factor, the true energy release from GRB is usually several orders magnitude smaller than observed isotropic value. Measuring opening angle, typically inferred an achromatic steepening in afterglow light curve (a "jet" break), has proven exceedingly difficult Swift era. Here we undertake study five brightest (in terms prompt release,...
Some supernovae (SNe) may be powered by the interaction of SN ejecta with a large amount circumstellar matter (CSM). However, quantitative estimates CSM mass around such SNe are missing when material is optically thick. Specifically, current estimators sensitive to uncertainties regarding density profile and velocity. Here we outline method measure thick SNe. We present new visible-light X-ray observations 2010jl (PTF 10aaxf), including first detection an in hard band using NuSTAR. The total...
GRB 130427A occurred in a relatively nearby galaxy; its prompt emission had the largest fluence ever recorded. The afterglow of was bright enough for Nuclear Spectroscopic Telescope ARray (NuSTAR) to observe it 3-79 keV energy range long after (~1.5 and 5 days). This range, where observations were previously not possible, bridges an important spectral gap. Combined with Swift, Fermi ground-based optical data, NuSTAR unambiguously establish single component from multi-GeV energies day event,...
Abstract We present new central stellar velocity dispersions for 484 Sy 1.9 and 2 from the second data release of Swift/BAT AGN Spectroscopic Survey (BASS DR2). This constitutes largest study dispersion measurements in X-ray-selected obscured active galactic nuclei (AGN) with 956 independent Ca ii H K λ 3969, 3934 Mg I 5175 region (3880–5550 Å) calcium triplet (8350–8730 642 spectra mainly VLT/X-Shooter or Palomar/DoubleSpec. Our sample spans 40–360 km s 1 , corresponding to 4–5 orders...
We report our discovery and early time optical, near-infrared, radio wavelength follow-up observations of the afterglow gamma-ray burst GRB 021211. Our optical observations, beginning 21 min after trigger, demonstrate that this is roughly three magnitudes fainter than 990123 at similar epochs, almost all known afterglows an epoch 1d GRB. near-infrared indicate not due to extinction. Combining with data reported by other groups, we identify signature a reverse shock. This shock detected...