Search Publications
The Globular Cluster Systems of Ultra-diffuse Galaxies in the Coma Cluster
den Brok, Mark; Côté, Patrick; Peng, Eric W. +4 more
Ultra-diffuse galaxies (UDGs) are unusual galaxies with low luminosities, similar to classical dwarf galaxies, but with sizes up to ∼5 larger than expected for their mass. Some UDGs have large populations of globular clusters (GCs), something unexpected in galaxies with such low stellar density and mass. We have carried out a comprehensive study o…
SILVERRUSH. V. Census of Lyα, [O III] λ5007, Hα, and [C II] 158 µm Line Emission with ∼1000 LAEs at z = 4.9-7.0 Revealed with Subaru/HSC
Ono, Yoshiaki; Ouchi, Masami; Martin, Crystal L. +23 more
We investigate Lyα, [O III] λ5007, Hα, and [C II] 158 µm emission from 1124 galaxies at z = 4.9-7.0. Our sample is composed of 1092 Lyα emitters (LAEs) at z = 4.9, 5.7, 6.6, and 7.0 identified by Subaru/Hyper-Suprime-Cam (HSC) narrowband surveys covered by Spitzer Large Area Survey with Hyper-Suprime-Cam (SPLASH) and 34 galaxies at z = 5.148…
A Window on the Earliest Star Formation: Extreme Photoionization Conditions of a High-ionization, Low-metallicity Lensed Galaxy at z ∼ 2*
Pettini, Max; Erb, Dawn K.; Brammer, Gabriel B. +2 more
We report new observations of SL2S J021737-051329, a lens system consisting of a bright arc at z = 1.84435, magnified ∼17× by a massive galaxy at z = 0.65. SL2S0217 is a low-mass (M < 109 M ⊙), low-metallicity (Z ∼ 1/20 Z ⊙) galaxy, with extreme star-forming conditions that produce strong nebular UV emission lin…
NICER and Fermi GBM Observations of the First Galactic Ultraluminous X-Ray Pulsar Swift J0243.6+6124
Remillard, Ronald A.; Chakrabarty, Deepto; Ray, Paul S. +20 more
Swift J0243.6+6124 is a newly discovered Galactic Be/X-ray binary, revealed in late 2017 September in a giant outburst with a peak luminosity of 2 × 1039(d/7 kpc)2 erg s-1 (0.1-10 keV), with no formerly reported activity. At this luminosity, Swift J0243.6+6124 is the first known galactic ultraluminous X-ray pulsar.…
Gaia-DR2 Confirms VLBA Parallaxes in Ophiuchus, Serpens, and Aquila
Kounkel, Marina; Rodríguez, Luis F.; Loinard, Laurent +9 more
We present Gaia-DR2 astrometry of a sample of YSO candidates in Ophiuchus, Serpens Main, and Serpens South/W40 in the Aquila Rift, which had been mainly identified by their infrared excess with Spitzer. We compare the Gaia-DR2 parallaxes against published and new parallaxes obtained from our Very Long Baseline Array (VLBA) program Gould’s Belt Dis…
The MOSDEF Survey: Direct Observational Constraints on the Ionizing Photon Production Efficiency, ξ ion, at z ∼ 2
Siana, Brian; Shapley, Alice E.; Reddy, Naveen A. +11 more
We combine Hα and Hβ spectroscopic measurements and UV photometry for a sample of 673 galaxies from the MOSDEF survey to constrain hydrogen-ionizing photon production efficiencies ({ξ }ion}) at z = 1.4-2.6. We find < {log}({ξ }ion}/[{{{s}}}-1/{erg} {{{s}}}-1 {Hz}}-1])> = 25.06 (25.34), a…
Spectra of Hydrogen-poor Superluminous Supernovae from the Palomar Transient Factory
Ellis, Richard; Filippenko, Alexei V.; Pan, Yen-Chen +20 more
Most Type I superluminous supernovae (SLSNe-I) reported to date have been identified by their high peak luminosities and spectra lacking obvious signs of hydrogen. We demonstrate that these events can be distinguished from normal-luminosity SNe (including Type Ic events) solely from their spectra over a wide range of light-curve phases. We use thi…
Age Determinations of the Hyades, Praesepe, and Pleiades via MESA Models with Rotation
Choi, Jieun; Conroy, Charlie; Dotter, Aaron +4 more
The Hyades, Praesepe, and Pleiades are well-studied stellar clusters that anchor important secondary stellar age indicators. Recent studies have shown that main sequence turn off based ages for these clusters may depend on the degree of rotation in the underlying stellar models. Rotation induces structural instabilities that can enhance the chemic…
The Milky Way Halo in Action Space
Myeong, G. C.; Evans, N. W.; Belokurov, V. +2 more
We analyze the structure of the local stellar halo of the Milky Way using ∼60000 stars with full phase space coordinates extracted from the SDSS-Gaia catalog. We display stars in action space as a function of metallicity in a realistic axisymmetric potential for the Milky Way Galaxy. The metal-rich population is more distended toward high radial a…
An Empirical Measurement of the Initial-Final Mass Relation with Gaia White Dwarfs
Rix, Hans-Walter; El-Badry, Kareem; Weisz, Daniel R.
We use data from Gaia’s second data release (DR2) to constrain the initial-final mass relation (IFMR) for field stars with initial masses 0.9 ≲ m in/M ⊙ ≲ 8. Precise parallaxes have revealed unprecedented substructure in the white dwarf (WD) cooling sequence on the color-magnitude diagram (CMD). Some of this substructure stem…