Search Publications
New Constraints on the Dark Matter Density Profiles of Dwarf Galaxies from Proper Motions of Globular Cluster Streams
Malhan, Khyati; Ibata, Rodrigo A.; Valluri, Monica +1 more
The central density profiles in dwarf galaxy halos depend strongly on the nature of dark matter (DM). Recently, in Malhan et al. we employed N-body simulations to show that the cuspy cold DM subhalos predicted by cosmological simulations can be differentiated from cored subhalos using the properties of accreted globular cluster (GC) streams since …
Evolution of the Spin, Spectrum and Superorbital Period of the Ultraluminous X-Ray Pulsar M51 ULX7
Israel, Gian Luca; Fürst, Felix; Walton, Dominic J. +6 more
M51 ULX7 is among a small group of known ultraluminous X-ray pulsars (ULXPs). The neutron star powering the source has a spin period of 2.8 s, orbits its companion star with a period of 2 days, and a superorbital period of 38 days is evident in its X-ray lightcurve. Here we present NuSTAR and XMM-Newton data on the source from 2019 obtained when t…
From the Fire: A Deeper Look at the Phoenix Stream
Smith, M.; Abbott, T. M. C.; Allam, S. +64 more
We use 6 yr of data from the Dark Energy Survey to perform a detailed photometric characterization of the Phoenix stellar stream, a 15° long, thin, dynamically cold, low-metallicity stellar system in the Southern Hemisphere. We use natural splines, a nonparametric modeling technique, to simultaneously fit the stream track, width, and linear densit…
Measuring Optical Extinction toward Young Stellar Objects Using Diffuse Interstellar Bands
Hillenbrand, Lynne A.; Carvalho, Adolfo S.
Line-of-sight extinction estimates of well-studied young T Tauri and Herbig Ae/Be stars are based on many different measurements and analysis methods. This has resulted in wide scatter among the published A V values for the same star. In this work, we discuss the challenges in measuring extinction to actively accreting and especially …
High-resolution Near-infrared Spectroscopy of a Flare around the Ultracool Dwarf vB 10
Kowalski, Adam F.; Cochran, William D.; Mahadevan, Suvrath +20 more
We present high-resolution observations of a flaring event in the M8 dwarf vB 10 using the near-infrared Habitable-zone Planet Finder (HPF) spectrograph on the Hobby-Eberly Telescope. The high stability of HPF enables us to accurately subtract a vB 10 quiescent spectrum from the flare spectrum to isolate the flare contributions and study the chang…
Excitation and Damping of Slow Magnetosonic Waves in Flaring Hot Coronal Loops: Effects of Compressive Viscosity
Ofman, Leon; Wang, Tongjiang
Slow magnetosonic waves associated with flares were observed in coronal loops by Solar and Heliospheric Observatory/Solar Ultraviolet Measurements of Emitted Radiation, Solar Dynamics Observatory/Atmospheric Imaging Assembly in various EUV bandpasses, and other instruments. The excitation and damping of slow magnetosonic waves provides information…
The Origin of the Doppler Flip in HD 100546: A Large-scale Spiral Arm Generated by an Inner Binary Companion
Ginski, Christian; Pinte, Christophe; Rosotti, Giovanni +9 more
Companions at subarcsecond separation from young stars are difficult to image. However, their presence can be inferred from the perturbations they create in the dust and gas of protoplanetary disks. Here we present a new interpretation of SPHERE polarized observations that reveal the previously detected inner spiral in the disk of HD 100546. The s…
Linking Small-scale Solar Wind Properties with Large-scale Coronal Source Regions through Joint Parker Solar Probe-Metis/Solar Orbiter Observations
Telloni, Daniele; Zank, Gary P.; Adhikari, Laxman +92 more
The solar wind measured in situ by Parker Solar Probe in the very inner heliosphere is studied in combination with the remote-sensing observation of the coronal source region provided by the METIS coronagraph aboard Solar Orbiter. The coronal outflows observed near the ecliptic by Metis on 2021 January 17 at 16:30 UT, between 3.5 and 6.3 R ⊙<…
Disconnecting the Dots: Re-examining the Nature of Stellar "Strings" in the Milky Way
Peek, J. E. G.; Zucker, Catherine; Loebman, Sarah
Recent analyses of Gaia data have resulted in the identification of new stellar structures, including a new class of extended stellar filaments called stellar "strings," first proposed by Kounkel & Covey. We explore the spatial, kinematic, and chemical composition of strings to demonstrate that these newfound structures are largely inconsisten…
The X-Ray Luminosity Function Evolution of Quasars and the Correlation between the X-Ray and Ultraviolet Luminosities
Singal, J.; Mutchnick, S.; Petrosian, V.
We explore the evolution of the X-ray luminosity function of quasars and the intrinsic correlation between the X-ray and 2500 Å ultraviolet luminosities, utilizing techniques verified in previous works and a sample of over 4000 quasars detected with Chandra and XMM-Newton in the range 0 < z < 5. We find that quasars have undergone significan…