A5072225825- Gamma-ray bursts and supernovae
- Astrophysical Phenomena and Observations
- Pulsars and Gravitational Waves Research
- Astrophysics and Cosmic Phenomena
- Astronomy and Astrophysical Research
- Astronomical Observations and Instrumentation
- Stellar, planetary, and galactic studies
- Galaxies: Formation, Evolution, Phenomena
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- High-pressure geophysics and materials
- Astrophysics and Star Formation Studies
- Astro and Planetary Science
- Nuclear Physics and Applications
- Particle Accelerators and Free-Electron Lasers
- Advanced X-ray Imaging Techniques
- Relativity and Gravitational Theory
- Geophysics and Gravity Measurements
- Laser-Plasma Interactions and Diagnostics
- History and Developments in Astronomy
- Adaptive optics and wavefront sensing
- X-ray Spectroscopy and Fluorescence Analysis
- Dark Matter and Cosmic Phenomena
- Ionosphere and magnetosphere dynamics
- Particle Detector Development and Performance
Michigan State University
2016-2025
Time Domain (United States)
2018-2025
Center for Astrophysics Harvard & Smithsonian
2011-2015
National Radio Astronomy Observatory
2011-2014
Harvard University Press
2012-2013
SKA Observatory
2011
Smithsonian Astrophysical Observatory
2011
Harvard University
2011
University of Wisconsin–Madison
2005-2010
Wesleyan University
2004-2005
The star formation rate (SFR) of the Milky Way remains poorly known, with often-quoted values ranging from 1 to 10 solar masses per year. This situation persists despite potential for serve as ultimate SFR calibrator external galaxies. We show that various estimates Galactic are consistent one another once they have been normalized same initial mass function (IMF) and massive models, converging 1.9 +/- 0.4 M_sun/yr. However, standard diagnostics vulnerable systematics founded in use indirect...
High-dispersion observations of the Na i D λλ5890, 5896 and K λλ7665, 7699 interstellar lines, diffuse band at 5780 Å in spectra 32 Type Ia supernovae are used as an independent means probing dust extinction. We show that extinction objects where is detected consistent with visual derived from supernova colors. This strongly suggests producing predominantly located medium host galaxies not circumstellar material associated progenitor system. One quarter display anomalously large column...
The double explosion of SN 2009ip in 2012 raises questions about our understanding the late stages massive star evolution. Here we present a comprehensive study during its remarkable rebrightenings. High-cadence photometric and spectroscopic observations from GeV to radio band obtained variety ground-based space facilities (including Very Large Array, Swift, Fermi, Hubble Space Telescope, XMM) constrain be low energy (E ∼ 1050 erg for an ejecta mass ∼0.5 M☉) asymmetric complex medium shaped...
Double detonations in double white dwarf (WD) binaries undergoing unstable mass transfer have emerged recent years as one of the most promising Type Ia supernova (SN Ia) progenitor scenarios. One potential outcome this "dynamically driven double-degenerate double-detonation" (D^6) scenario is that companion WD survives explosion and flung away with a velocity equal to its > 1000 km/s pre-SN orbital velocity. We perform search for these hypervelocity runaway WDs using Gaia's second data...
The GLIMPSE (Galactic Legacy Mid-Plane Survey Extraordinaire) Point Source Catalog of ~30 million mid-infrared sources toward the inner Galaxy, 10° ≤ |l| 65° and |b| 1°, was used to determine distribution stars in Galactic longitude, l, latitude, b, apparent magnitude, m. counts versus longitude can be approximated by modified Bessel function N = N0(l/l0)K1(l/l0), where l0 is insensitive limiting band choice, side center: 17°-30° with a best-fit value 4.5 μm 24° ± 4°. Modeling source as an...
We present the Pan-STARRS1 discovery of long-lived and blue transient PS1-11af, which was also detected by Galaxy Evolution Explorer with coordinated observations in near-ultraviolet (NUV) band. PS1-11af is associated nucleus an early type galaxy at redshift z = 0.4046 that exhibits no evidence for star formation or active galactic activity. Four epochs spectroscopy reveal a pair broad absorption features UV on otherwise featureless spectra. Despite superficial similarity these to P-Cygni...
We present the discovery of two ultra-luminous supernovae (SNe) at z ~ 0.9 with Pan-STARRS1 Medium-Deep Survey. These SNe, PS1-10ky and PS1-10awh, are amongst most luminous SNe ever discovered, comparable to unusual transients SN 2005ap SCP 06F6. Like 06F6, they show characteristic high luminosities (M_bol -22.5 mag), blue spectra a few broad absorption lines, no evidence for H or He. have constructed full multi-color light curve sensitive peak spectral energy distribution in rest-frame...
We present multi-wavelength observations of SN 2014C during the first 500 days. These represent solid detection a young extragalactic stripped-envelope out to high-energy X-rays ~40 keV. shows ordinary explosion parameters (Ek ~ 1.8 × 1051 erg and Mej 1.7 M⊙). However, over an ~1 year timescale, evolved from hydrogen-poor supernova into strongly interacting, hydrogen-rich supernova, violating traditional classification scheme type-I versus type-II SNe. Signatures shock interaction with dense...
We report the discovery of a candidate stellar-mass black hole in Milky Way globular cluster M62. detected candidate, which we term M62-VLA1, core using deep radio continuum imaging from Karl G. Jansky Very Large Array. M62-VLA1 is faint source, with flux density 18.7 +/- 1.9 microJy at 6.2 GHz and flat spectrum (alpha=-0.24 0.42, for S_nu = nu^alpha). M62 second hole; unlike two holes previously found M22, associated Chandra X-ray supporting its identification as binary. Measurements...
We report unique EVLA observations of SN 2011fe representing the most sensitive radio study a Type Ia supernova to date. Our data place direct constraints on density surrounding medium at radii ~10^15-10^16 cm, implying an upper limit mass loss rate from progenitor system Mdot <~ 6 x 10^-10 Msol/yr (assuming wind speed 100 km/s), or expansion into uniform with n_CSM cm^-3. Drawing observed properties non-conservative transfer among accreting white dwarfs, we use these limits immediate...
We report the discovery and detailed monitoring of X-ray emission associated with Type IIb SN 2011dh using data from Swift Chandra satellites, placing it among best-studied supernovae (SNe) to date. further present millimeter radio obtained Submillimeter Array, Combined Array for Research in Millimeter-wave Astronomy, Expanded Very Large during first three weeks after explosion. Combining these observations early optical photometry, we show that panchromatic set is well described by...
We report the detection of steady radio emission from known X-ray source X9 in globular cluster 47 Tuc. With a double-peaked C IV line its ultraviolet spectrum providing clear signature accretion, this had been previously classified as cataclysmic variable. In deep ATCA imaging 2010 and 2013, we identified at both 5.5 9.0 GHz, with spectral index (defined $S_{\nu}\propto\nu^{\alpha}$) $\alpha=-0.4\pm0.4$. Our measured flux density $42\pm4$ microJy/beam GHz implies luminosity ($\nu L_{\nu}$)...
Our current understanding of galaxy evolution still has many uncertainties associated with the details accretion, processing, and removal gas across cosmic time. The next generation radio telescopes will image neutral hydrogen (HI) in galaxies over large volumes at high redshifts, which provide key insights into these processes. We are conducting COSMOS HI Large Extragalactic Survey (CHILES) Karl G. Jansky Very Array, is first survey to simultaneously observe from z=0 z~0.5. Here, we report...
ABSTRACT Searches for circumstellar material around Type Ia supernovae (SNe Ia) are some of the most powerful tests nature SN progenitors, and radio observations provide a particularly sensitive probe this material. Here, we report SNe their lower-luminosity thermonuclear cousins. We present largest, sensitive, spectroscopically diverse study prompt ( <?CDATA ${\rm{\Delta }}t\lesssim 1$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi...
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...
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...
We survey our understanding of classical novae—nonterminal, thermonuclear eruptions on the surfaces white dwarfs in binary systems. The recent and unexpected discovery GeV gamma rays from Galactic novae has highlighted complexity their value as laboratories for studying shocks particle acceleration. review half a century nova literature through this new lens, conclude following: ▪ basics runaway theory are confirmed by observations. dwarf sustains surface nuclear burning some time after...
We present the discovery and early evolution of ASASSN-19bt, a tidal disruption event (TDE) discovered by All-Sky Automated Survey for Supernovae (ASAS-SN) at distance $d\simeq115$ Mpc first TDE to be detected TESS. As is located in TESS Continuous Viewing Zone, our dataset includes 30-minute cadence observations starting on 2018 July 25, we precisely measure that begins brighten $\sim8.3$ days before its discovery. Our also 18 epochs Swift UVOT XRT observations, 2 XMM-Newton 13...
We present the discovery of ASASSN-18ey (MAXI J1820+070), a new black hole low-mass X-ray binary discovered by All-Sky Automated Survey for SuperNovae (ASAS-SN). A week after ASAS-SN as an optical transient, it was detected transient MAXI/GCS. Here, we analyze and Asteroid Terrestrial-impact Last Alert System (ATLAS) pre-outburst light curves, finding evidence intrinsic variability several years prior to outburst. While there no long-term rise leading outburst, has been seen in other...
We present a global analysis of kinematics and metallicity in the nearest S0 galaxy, NGC 3115, along with implications for its assembly history. The data include high-quality wide-field imaging from Suprime-Cam on Subaru telescope, multi-slit spectra field stars globular clusters (GCs) obtained using Keck-DEIMOS/LRIS Magellan-IMACS. Within two effective radii, bulge (as traced by metal-rich GCs) is flattened rotates rapidly (v/σ ≳ 1.5). At larger rotation declines dramatically to v/σ ∼ 0.7,...