Search Publications
Probing Dark Matter Subhalos in Galaxy Clusters Using Highly Magnified Stars
Dai, Liang; Venumadhav, Tejaswi; Kaurov, Alexander A. +1 more
Luminous stars in background galaxies straddling the lensing caustic of a foreground galaxy cluster can be individually detected due to extreme magnification factors of ∼102-103, as recently observed in deep HST images. We propose a direct method to probe the presence of dark matter subhalos in galaxy clusters by measuring th…
A Chandra/LETGS Survey of Main-sequence Stars
Warren, Harry P.; Wood, Brian E.; Poppenhaeger, Katja +1 more
We analyze the X-ray spectra of 19 main-sequence stars observed by Chandra using its LETGS configuration. Emission measure (EM) distributions are computed based on emission line measurements, an analysis that also yields evaluations of coronal abundances. The use of newer atomic physics data results in significant changes compared to past publishe…
SMASHing the LMC: Mapping a Ring-like Stellar Overdensity in the LMC Disk
Bell, Eric F.; Monachesi, Antonela; Choi, Yumi +18 more
We explore the stellar structure of the Large Magellanic Cloud (LMC) disk using data from the Survey of the MAgellanic Stellar History and the Dark Energy Survey. We detect a ring-like stellar overdensity in the red clump star count map at a radius of ∼6° (∼5.2 kpc at the LMC distance) that is continuous over ∼270° in position angle and is only li…
X-Ray Census of Millisecond Pulsars in the Galactic Field
Cheng, K. S.; Takata, J.; Kong, A. K. H. +3 more
We have conducted a systematic survey for the X-ray properties of millisecond pulsars (MSPs). Currently, there are 47 MSPs with confirmed X-ray detections. We have also placed the upper limits for the X-ray emission from the other 36 MSPs by using the archival data. We have normalized their X-ray luminosities L x and their effective p…
The SFR-M * Correlation Extends to Low Mass at High Redshift
Finkelstein, Steven L.; Koekemoer, Anton M.; Somerville, Rachel S. +8 more
To achieve a fuller understanding of galaxy evolution, SED fitting can be used to recover quantities beyond stellar masses (M *) and star formation rates (SFRs). We use star formation histories (SFHs) reconstructed via the Dense Basis method of Iyer & Gawiser for a sample of 17,873 galaxies at 0.5 < z < 6 in the Cosmic Assembl…
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