Search Publications
Coherent Structures at Ion Scales in Fast Solar Wind: Cluster Observations
Maksimovic, M.; Alexandrova, O.; Lion, S. +5 more
We investigate the nature of magnetic turbulent fluctuations, around ion characteristic scales, in a fast solar wind stream, by using Cluster data. Contrarily to slow solar wind, where both Alfvénic (δ {b}\perp \gg δ {b}\parallel ) and compressive (δ {b}\parallel \gg δ {b}\perp ) coherent structures are …
NGC 1866: First Spectroscopic Detection of Fast-rotating Stars in a Young LMC Cluster
Mateo, M.; Crane, J. D.; Milone, A. P. +6 more
High-resolution spectroscopic observations were taken of 29 extended main-sequence turnoff (eMSTO) stars in the young (∼200 Myr) Large Magellanic Cloud (LMC) cluster, NGC 1866, using the Michigan/Magellan Fiber System and MSpec spectrograph on the Magellan-Clay 6.5 m telescope. These spectra reveal the first direct detection of rapidly rotating st…
On the Early-time Excess Emission in Hydrogen-poor Superluminous Supernovae
Filippenko, Alexei V.; Cenko, S. Bradley; Sollerman, Jesper +27 more
We present the light curves of the hydrogen-poor superluminous supernovae (SLSNe I) PTF 12dam and iPTF 13dcc, discovered by the (intermediate) Palomar Transient Factory. Both show excess emission at early times and a slowly declining light curve at late times. The early bump in PTF 12dam is very similar in duration (∼10 days) and brightness relati…
An Ultraviolet Excess in the Superluminous Supernova Gaia16apd Reveals a Powerful Central Engine
Berger, E.; Challis, P.; Chornock, R. +5 more
Since the discovery of superluminous supernovae (SLSNe) in the last decade, it has been known that these events exhibit bluer spectral energy distributions than other supernova subtypes, with significant output in the ultraviolet. However, the event Gaia16apd seems to outshine even the other SLSNe at rest-frame wavelengths below ∼3000 Å. Yan et al…
A Comprehensive Study of Lyα Emission in the High-redshift Galaxy Population
Blanc, Guillermo A.; Oyarzún, Grecco A.; Mateo, Mario +2 more
We present an exhaustive census of Lyman alpha (Lyα) emission in the general galaxy population at 3< z< 4.6. We use the Michigan/Magellan Fiber System (M2FS) spectrograph to study a stellar mass (M {}* ) selected sample of 625 galaxies homogeneously distributed in the range 7.6< {log} {M}* /{M}⊙ < 10.6.…
Two New Calcium-rich Gap Transients in Group and Cluster Environments
Gal-Yam, A.; Kulkarni, S. R.; Filippenko, A. V. +20 more
We present the Palomar Transient Factory discoveries and the photometric and spectroscopic observations of PTF11kmb and PTF12bho. We show that both transients have properties consistent with the class of calcium-rich gap transients, specifically lower peak luminosities and rapid evolution compared to ordinary supernovae, and a nebular spectrum dom…
The Initial Mass Function in the Nearest Strong Lenses from SNELLS: Assessing the Consistency of Lensing, Dynamical, and Spectroscopic Constraints
van Dokkum, Pieter; Conroy, Charlie; Newman, Andrew B. +2 more
We present new observations of the three nearest early-type galaxy (ETG) strong lenses discovered in the SINFONI Nearby Elliptical Lens Locator Survey (SNELLS). Based on their lensing masses, these ETGs were inferred to have a stellar initial mass function (IMF) consistent with that of the Milky Way, not the bottom-heavy IMF that has been reported…
Alignment between Protostellar Outflows and Filamentary Structure
Bourke, Tyler L.; Myers, Philip C.; Dunham, Michael M. +13 more
We present new Submillimeter Array (SMA) observations of CO(2-1) outflows toward young, embedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA (MASSES) survey. For 57 Perseus protostars, we characterize the orientation of the outflow angles and compare them with the orien…
Fundamental Physics with the Hubble Frontier Fields: Constraining Dark Matter Models with the Abundance of Extremely Faint and Distant Galaxies
Castellano, M.; Grazian, A.; Menci, N. +4 more
We show that the measured abundance of ultra-faint lensed galaxies at z≈ 6 in the Hubble Frontier Fields (HFF) provides stringent constraints on the parameter space of (I) dark matter models based on keV sterile neutrinos; (II) “fuzzy” wavelike dark matter models, based on Bose-Einstein condensates of ultra-light particles. For the case of sterile…
The Progenitor and Early Evolution of the Type IIb SN 2016gkg
Lundqvist, P.; Gal-Yam, A.; Smith, M. +24 more
We report initial observations and analysis on the Type IIb SN 2016gkg in the nearby galaxy NGC 613. SN 2016gkg exhibited a clear double-peaked light curve during its early evolution, as evidenced by our intensive photometric follow-up campaign. SN 2016gkg shows strong similarities with other Type IIb SNe, in particular, with respect to the He I e…