Search Publications
The Missing Metal Problem in Galaxy Clusters: Characterizing the Early Enrichment Population
Bregman, Joel N.; Blackwell, Anne E.; Snowden, Steven L.
Rich and poor galaxy clusters have the same measured halo metallicity, 0.35-0.4 Z ⊙, even though they are an order of magnitude apart in stellar fraction, M */M gas. The measured intracluster medium (ICM) metallicity in high-mass clusters cannot be explained by the visible stellar population as stars typically make…
On the Nature of Rotation in the Praesepe Cluster
Hao, C. J.; Xu, Y.; Hou, L. G. +4 more
Although a large number of Galactic open clusters (OCs) have been identified, the internal kinematic properties (e.g., rotation) of almost all the known OCs are still far from clear. With the high-precision astrometric data of Gaia EDR3, we have developed a methodology to unveil the rotational properties of the Praesepe cluster. Statistics of the …
A Radio-selected Population of Dark, Long Gamma-Ray Bursts: Comparison to the Long Gamma-Ray Burst Population and Implications for Host Dust Distributions
Kilpatrick, Charles D.; Andrews, Jennifer; Miller, Adam A. +17 more
We present centimeter-band and millimeter-band afterglow observations of five long-duration γ-ray bursts (GRBs; GRB 130131A, 130420B, 130609A, 131229A, 140713A) with dust-obscured optical afterglow emission, known as "dark" GRBs. We detect the radio afterglow of two of the dark GRBs (GRB 130131A and 140713A), along with a tentative detection of a …
X-Ray Observations of the Isolated Black Hole Candidate OGLE-2011-BLG-0462 and Other Collapsed Objects Discovered through Gravitational Microlensing
Mereghetti, S.; Ponti, G.; Sidoli, L. +1 more
Isolated black holes and neutron stars can be revealed through the observation of long-duration gravitational microlensing events. A few candidates have been found in surveys of stars in the direction of the Galactic bulge. Recently, thanks to the addition of astrometric information at milliarcsecond level, it has been possible to reduce the uncer…
Spectral Evolution of Ultraluminous X-Ray Pulsar NGC 300 ULX-1
Steiner, James F.; Remillard, Ronald A.; Chakrabarty, Deepto +2 more
We report on results from a 1 yr soft X-ray observing campaign of the ultraluminous X-ray pulsar NGC 300 ULX-1 by the Neutron star Interior Composition Explorer (NICER) during 2018-2019. Our analysis also made use of data from Swift/XRT and XMM-Newton in order to model and remove contamination from the nearby eclipsing X-ray binary NGC 300 X-1. We…
Improving Planet Detection with Disk Modeling: Keck/NIRC2 Imaging of the HD 34282 Single-armed Protoplanetary Disk
Dong, Ruobing; Millar-Blanchaer, Maxwell A.; Wallack, Nicole L. +5 more
Formed in protoplanetary disks around young stars, giant planets can leave observational features such as spirals and gaps in their natal disks through planet-disk interactions. Although such features can indicate the existence of giant planets, protoplanetary disk signals can overwhelm the innate luminosity of planets. Therefore, in order to imag…
Breaking Correlation in the Inflow Parameters of Interstellar Neutral Gas in Direct-sampling Observations
Möbius, E.; Schwadron, N. A.; Bzowski, M. +1 more
We analyze the reasons for the correlation between the temperature, direction, and speed of the interstellar neutral gas inflow into the heliosphere, obtained in analyses of observations performed by an onboard Interstellar Boundary Explorer (IBEX) instrument, IBEX-Lo. We point out that this correlation is the combined result of the inability to m…
A Study of 90 GHz Dust Emissivity on Molecular Cloud and Filament Scales
Hensley, Brandon; Friesen, Rachel; Sadavoy, Sarah +19 more
Recent observations from the MUSTANG2 instrument on the Green Bank Telescope have revealed evidence of enhanced long-wavelength emission in the dust spectral energy distribution (SED) in the Orion Molecular Cloud (OMC) 2/3 filament on 25″ (0.1 pc) scales. Here we present a measurement of the SED on larger spatial scales (map size 0.°5-3° or 3-20 p…
Anomalous Orbital Characteristics of the AQ Col (EC 05217-3914) System
von Hippel, T.; Silvotti, R.; Kilkenny, D. +6 more
AQ Col (EC 05217-3914) is one of the first detected pulsating subdwarf B (sdB) stars and has been considered to be a single star. Photometric monitoring of AQ Col reveals a pulsation timing variation with a period of 486 days, interpreted as time delay due to reflex motion in a wide binary formed with an unseen companion with expected mass larger …
Galactic Cosmic Rays at Mars and Venus: Temporal Variations from Hours to Decades Measured as the Background Signal of Onboard Microchannel Plates
Barabash, Stas; Nilsson, Hans; Holmström, Mats +8 more
A microchannel plate (MCP) is a component widely used for counting particles in space. Using the background counts from MCPs on the Mars Express and Venus Express orbiters-operating over 17 yr and 8 yr, respectively-we investigated the galactic cosmic ray (GCR) characteristics of the inner solar system. The MCP background counts at Mars and Venus,…