Search Publications
A New Window into the Nature of X-Ray Binaries in M101 from Their Optical Emission
Chandar, Rupali; Mok, Angus; Gallo, Elena +3 more
The high-energy emission from nearby, star-forming galaxies is dominated by X-ray binaries, where a neutron star or black hole is accreting mass from either a low-mass (≲3 M⊙) or high-mass (≳8 M⊙) star. Donor stars with intermediate masses ≈3-7 M⊙ are also possible, but rarer in our Galaxy. Since it is not possible…
VLT/X-Shooter Spectroscopy of Lyman Break Analogs: Direct-method O/H Abundances and Nitrogen Enhancements
Heckman, Timothy M.; Overzier, Roderik A.; Loaiza-Agudelo, Maryory
We used Very Large Telescope/X-Shooter to target a sample of nearby analogs of Lyman break galaxies (LBGs). These Lyman break analogs are similar to the LBGs in many of their physical properties. We determine electron temperatures using the weak [O III] λ4363 emission line and determine the oxygen abundance (O/H) using the direct and strong-line m…
An Ejecta Kinematics Study of Kepler's Supernova Remnant with High-resolution Chandra HETG Spectroscopy
Sato, Toshiki; Hughes, John P.; Slane, Patrick +6 more
We report our measurements of the bulk radial velocity from a sample of small, metal-rich ejecta knots in Kepler's supernova remnant (SNR). We measure the Doppler shift of the He-like Si Kα line-center energy in the spectra of these knots based on our Chandra High-Energy Transmission Grating Spectrometer observation to estimate their radial veloci…
Assessment of Systematic Uncertainties in the Cosmological Analysis of the SDSS Supernovae Photometric Sample
Scolnic, Dan; Kessler, Richard; Popovic, Brodie
Improvements to the precision of measurements of cosmological parameters with Type Ia supernovae (SNe Ia) are expected to come from large photometrically identified (photometric) supernova (SN) samples. Here we reanalyze the Sloan Digital Sky Survey (SDSS) photometric SN sample, with roughly 700 high-quality, likely but unconfirmed SNe Ia light cu…
Chandra Observations of High-energy X-Ray Sources Discovered by INTEGRAL
Hare, Jeremy; Rahoui, Farid; Fornasini, Francesca M. +6 more
The International Gamma-Ray Astrophysics Laboratory (INTEGRAL) satellite has detected in excess of 1000 sources in the ∼20-100 keV band during its surveys of the sky over the past 17 years. We obtained 5 ks observations of 15 unclassified INTEGRAL Gamma-Ray (IGR) sources with the Chandra X-ray Observatory in order to localize them, to identify opt…
Local Molecular Gas toward the Aquila Rift Region
Chen, Zhiwei; Wang, Hongchi; Gong, Yan +11 more
We present the results of a ∼250 square degrees CO mapping (+26° ≲ l ≲ +50° and -5° ≲ b ≲ +5°) toward the Aquila Rift region at a spatial resolution of ∼50″ and a grid spacing of 30″. The high dynamic range CO maps with a spectral resolution of ∼0.2 km s-1 display highly structured molecular cloud (MC) morphologies with valuable velocit…
The Supernova Remnant Population of NGC 6946 as Observed in [Fe II] 1.644 µm with HST
Blair, William P.; Long, Knox S.; Winkler, P. Frank +1 more
NGC 6946 is a high-star-formation-rate, face-on, spiral galaxy that has hosted 10 supernovae since 1917. Not surprisingly, a large number of supernova remnants and candidates have been identified either as optical nebulae with high [S II]:Hα line ratios (147) or as compact non-thermal radio sources (35). However, there are only seven overlaps betw…
A Year-long Superoutburst from an Ultracompact White Dwarf Binary Reveals the Importance of Donor Star Irradiation
Maccarone, T. J.; Rivera Sandoval, L. E.; Pichardo Marcano, M.
SDSS J080710+485259 is the longest-period outbursting ultracompact white dwarf binary. Its first-ever detected superoutburst started in 2018 November and lasted for a year, the longest detected so far for any short orbital period accreting white dwarf. Here we show the superoutburst duration of SDSS J080710+485259 exceeds the ∼2 month viscous time…
The HSC-SSP Transient Survey: Implications from Early Photometry and Rise Time of Normal Type Ia Supernovae
Tominaga, Nozomu; Nomoto, Ken'ichi; Morokuma, Tomoki +9 more
With a booming number of Type Ia supernovae (SNe Ia) discovered within a few days of their explosions, a fraction of SNe Ia that show luminosity excess in the early phase (early-excess SNe Ia) have been confirmed. In this article, we report early-phase observations of seven photometrically normal SNe Ia (six early detections and one deep non detec…
The Eroding Disk of AU Mic
Augereau, J. -C.; Henning, Th.; Milli, J. +12 more
We report Hubble Space Telescope (HST) Space Telescope Imaging Spectrograph imaging of AU Mic's debris disk from 2017 and archival data. Outward motion of the features in the southeast arm continues. At least three features have reached or exceeded projected escape velocity in the past decade, yielding a combined feature mass-loss rate of ∼1.2 × 1…