Search Publications
Where Do Quasar Hosts Lie with Respect to the Size-Mass Relation of Galaxies?
Kartaltepe, Jeyhan S.; Treu, Tommaso; Schramm, Malte +8 more
The evolution of the galaxy size-mass relation has been a puzzle for over a decade. High-redshift galaxies are significantly more compact than galaxies observed today at an equivalent mass, but how much of this apparent growth is driven by progenitor bias, minor mergers, secular processes, or feedback from active galactic nuclei (AGNs) is unclear.…
12,660 Spotted Stars toward the OGLE Galactic Bulge Fields
Soszyński, I.; Udalski, A.; Szymański, M. K. +12 more
We present the discovery and statistical analysis of 12,660 spotted variable stars toward and inside the Galactic bulge from the Optical Gravitational Lensing Experiment (OGLE) data that are over two decades long. We devise a new method of dereddening of individual stars toward the Galactic bulge where strong and highly nonuniform extinction is pr…
The Galactic Bulge Diffuse Emission in Broadband X-Rays with NuSTAR
Wik, Daniel R.; Krivonos, Roman; Perez, Kerstin
The diffuse hard X-ray emission that fills the Galactic center, bulge, and ridge is believed to arise from unresolved populations of X-ray binary systems. However, the identity of the dominant class of accreting objects in each region remains unclear. Recent studies of Fe line properties and the low-energy (<10 keV) X-ray continuum of the bulge…
The Carnegie Chicago Hubble Program. VI. Tip of the Red Giant Branch Distances to M66 and M96 of the Leo I Group
Madore, Barry F.; Freedman, Wendy L.; Beaton, Rachael L. +8 more
We determine the distances to the Type Ia supernova host galaxies M66 (NGC 3627) and M96 (NGC 3368) of the Leo I Group using the Tip of the Red Giant Branch (TRGB) method. We target the stellar halos of these galaxies using the Hubble Space Telescope ACS/WFC in the F606W and F814W bandpasses. By pointing to the stellar halos we sample RGB stars pr…
Constraining the Dark-matter Halo Mass of Isolated Low-surface-brightness Galaxies
Bogdán, Ákos; Canning, Rebecca E. A.; Kovács, Orsolya E.
Recent advancements in the imaging of low-surface-brightness objects revealed numerous ultra-diffuse galaxies in the local universe. These peculiar objects are unusually extended and faint: their effective radii are comparable to the Milky Way, but their surface brightnesses are lower than that of dwarf galaxies. Their ambiguous properties motivat…
Investigating the Covering Fraction Distribution of Swift/BAT AGNs with X-Ray and Infrared Observations
Ricci, Claudio; Goulding, Andy D.; Bauer, Franz E. +13 more
We present an analysis of a sample of 69 local obscured Swift/Burst Alert Telescope active galactic nuclei (AGNs) with X-ray spectra from NuSTAR and infrared (IR) spectral energy distributions from Herschel and WISE. We combine this X-ray and IR phenomenological modeling and find a significant correlation between reflected hard X-ray emission and …
The Impact of Turbulent Solar Wind Fluctuations on Solar Orbiter Plasma Proton Measurements
Owen, C. J.; Nicolaou, G.; Verscharen, D. +1 more
Solar Orbiter will observe the Sun and the inner heliosphere to study the connections between solar activity, coronal structure, and the origin of the solar wind. The plasma instruments on board Solar Orbiter will determine the three-dimensional velocity distribution functions of the plasma ions and electrons with high time resolution. The analysi…
Evidence for Asymmetry in the Velocity Distribution of the Interstellar Neutral Helium Flow Observed by IBEX and Ulysses
Wood, Brian E.; Müller, Hans-Reinhard; Möbius, Eberhard
We use observations from the Interstellar Boundary Explorer (IBEX) and Ulysses to explore the possibility that the interstellar neutral helium flowing through the inner solar system possesses an intrinsic non-Maxwellian velocity distribution. In fitting the IBEX and Ulysses data, we experiment with both a kappa distribution and a bi-Maxwellian, in…
Subkiloparsec Imaging of Lyα Emission in a Low-mass, Highly Ionized, Gravitationally Lensed Galaxy at z = 1.84
Pettini, Max; Erb, Dawn K.; Brammer, Gabriel +3 more
Low-mass, low-metallicity galaxies at low to moderate (z ≲ 3) redshifts offer the best opportunity for detailed examination of the interplay between massive stars, ionizing radiation and gas in sources similar to those that likely reionized the universe. We present new narrowband Hubble Space Telescope observations of {Ly}α emission and the adjace…
HST Resolves Stars in a Tiny Body Falling on the Dwarf Galaxy DDO 68
Cignoni, M.; Tosi, M.; Calzetti, D. +9 more
We present new Hubble Space Telescope imaging of a stream-like system associated with the dwarf galaxy DDO 68, located in the Lynx-Cancer void at a distance of D ∼ 12.65 Mpc from us. The stream, previously identified in deep Large Binocular Telescope images as a diffuse low surface brightness structure, is resolved into individual stars in the F60…