Search Publications
The Properties of GRB 120923A at a Spectroscopic Redshift of z ≈ 7.8
Cenko, S. B.; Covino, S.; Sánchez-Ramírez, R. +37 more
Gamma-ray bursts (GRBs) are powerful probes of early stars and galaxies, during and potentially even before the era of reionization. Although the number of GRBs identified at z ≳ 6 remains small, they provide a unique window on typical star-forming galaxies at that time, and thus are complementary to deep field observations. We report the identifi…
The Ultra-fast Outflow of the Quasar PG 1211+143 as Viewed by Time-averaged Chandra Grating Spectroscopy
Kriss, Gerard A.; Lee, Julia C.; Chakravorty, Susmita +8 more
We present a detailed X-ray spectral study of the quasar PG 1211+143 based on Chandra High Energy Transmission Grating Spectrometer (HETGS) observations collected in a multi-wavelength campaign with UV data using the Hubble Space Telescope Cosmic Origins Spectrograph (HST-COS) and radio bands using the Jansky Very Large Array (VLA). We constructed…
The Dispersion of Fast Radio Bursts from a Structured Intergalactic Medium at Redshifts z < 1.5
Shull, J. Michael; Danforth, Charles W.
We analyze the sources of free electrons that produce the large dispersion measures, {DM}≈ 300{--}1600 (in units of cm-3 pc), observed toward fast radio bursts (FRBs). Individual galaxies typically produce {DM}∼ 25{--}60 {{cm}}-3 {pc} from ionized gas in their disk, disk-halo interface, and circumgalactic medium. Toward an FR…
First Results of an ALMA Band 10 Spectral Line Survey of NGC 6334I: Detections of Glycolaldehyde (HC(O)CH2OH) and a New Compact Bipolar Outflow in HDO and CS
McGuire, Brett A.; van Dishoeck, Ewine F.; Blake, Geoffrey A. +9 more
We present the first results of a pilot program to conduct an Atacama Large Millimeter Array (ALMA) band 10 spectral line survey of the high-mass star-forming region NGC 6334I. The observations were taken in exceptional weather conditions (0.19 mm precipitable water) with typical system temperatures T sys < 950 K at ∼890 GHz. A brigh…
The 30 Year Search for the Compact Object in SN 1987A
Baes, Maarten; Matsuura, Mikako; Fransson, Claes +32 more
Despite more than 30 years of searching, the compact object in Supernova (SN) 1987A has not yet been detected. We present new limits on the compact object in SN 1987A using millimeter, near-infrared, optical, ultraviolet, and X-ray observations from ALMA, VLT, HST, and Chandra. The limits are approximately 0.1 mJy (0.1× {10}-26 erg s
MUSE Spectroscopic Identifications of Ultra-faint Emission Line Galaxies with M UV ∼ -15
Bacon, Roland; Bouché, Nicolas; Inami, Hanae +16 more
Using an ultra-deep blind survey with the MUSE integral field spectrograph on the European Southern Observatory Very Large Telescope, we obtain spectroscopic redshifts to a depth never before explored: galaxies with observed magnitudes m AB ≳ 30-32. Specifically, we detect objects via Lyα emission at 2.9 < z < 6.7 without individu…
ALMA Resolves C I Emission from the β Pictoris Debris Disk
Roberge, Aki; Pantin, Eric; Cataldi, Gianni +8 more
The debris disk around β Pictoris is known to contain gas. Previous ALMA observations revealed a CO belt at ∼85 au with a distinct clump, interpreted as a location of enhanced gas production. Photodissociation converts CO into C and O within ∼50 a. We resolve C I emission at 492 GHz using ALMA and study its spatial distribution. C I shows the same…
A Geometrical 1% Distance to the Short-period Binary Cepheid V1334 Cygni
Nelan, E.; Mowlavi, N.; Eyer, L. +18 more
Cepheid stars play a considerable role as extragalactic distances indicators, thanks to the simple empirical relation between their pulsation period and their luminosity. They overlap with that of secondary distance indicators, such as Type Ia supernovae, whose distance scale is tied to Cepheid luminosities. However, the period-luminosity (P-L) re…
An Ultra Metal-poor Star Near the Hydrogen-burning Limit
Casey, Andrew R.; Thompson, Ian B.; Schlaufman, Kevin C.
It is unknown whether or not low-mass stars can form at low metallicity. While theoretical simulations of Population III (Pop III) star formation show that protostellar disks can fragment, it is impossible for those simulations to discern if those fragments survive as low-mass stars. We report the discovery of a low-mass star on a circular orbit w…
Multi-episode Chromospheric Evaporation Observed in a Solar Flare
Tian, H.; Chen, N. -H.
With observations of the Interface Region Imaging Spectrograph (IRIS), we study chromospheric heating and evaporation during an M1.6 flare SOL2015-03-12T11:50. At the flare ribbons, the Mg II 2791.59 Å line shows quasi-periodic short-duration red-wing enhancement, which is likely related to repetitive chromospheric condensation as a result of epis…