Search Publications
Major Mergers Are Not the Dominant Trigger for High-accretion AGNs at z ∼ 2
Cohen, Seth; van der Wel, Arjen; Windhorst, Rogier A. +8 more
Research over the past decade has shown diminishing evidence for major galaxy mergers being a dominant mechanism for the growth of supermassive black holes (BHs) in galaxies and the triggering of optically or X-ray-selected active galactic nuclei (AGNs). For the first time we test whether such a connection exists at least in the most “plausible” p…
A Uniform Retrieval Analysis of Ultra-cool Dwarfs. III. Properties of Y Dwarfs
Line, Michael R.; Schneider, Adam C.; Patience, Jennifer +1 more
Ultra-cool brown dwarfs offer a unique window into understanding substellar atmospheric physics and chemistry. Their strong molecular absorption bands at infrared wavelengths, Jupiter-like radii, cool temperatures, and lack of complicating stellar irradiation make them ideal test beds for understanding Jovian-like atmospheres. Here, we report the …
Particle Acceleration at 5 au Associated with Turbulence and Small-scale Magnetic Flux Ropes
Chen, Y.; Zank, G. P.; Zhao, L. -L. +4 more
An observational analysis of an atypical energetic particle event near 5 au measured by the Ulysses spacecraft is presented. A previous study has attributed the unusual enhancement of energetic proton flux to the presence of small-scale dynamic magnetic islands or flux ropes. Here, we find that the generation of these magnetic islands may be relat…
Discovery of Strongly Inverted Metallicity Gradients in Dwarf Galaxies at z ∼ 2
Schmidt, Kasper B.; Treu, Tommaso; Daddi, Emanuele +12 more
We report the first measurements with sub-kiloparsec spatial resolution of strongly inverted gas-phase metallicity gradients in two dwarf galaxies at z ∼ 2. The galaxies have stellar masses ∼109 {M}⊙ , specific star formation rate ∼20 Gyr-1, and global metallicity 12+{log}({{O}}/{{H}})∼ 8.1 (1/4 solar), assuming t…
Tidally Induced Radius Inflation of Sub-Neptunes
Millholland, Sarah
Recent work suggests that many short-period super-Earth and sub-Neptune planets may have significant spin axis tilts (“obliquities”). When planets are locked in high-obliquity states, the tidal dissipation rate may increase by several orders of magnitude. This intensified heat deposition within the planets’ interiors should generate significant st…
Multiple Spiral Arms in the Disk around Intermediate-mass Binary HD 34700A
Monnier, John D.; Kraus, Stefan; Oppenheimer, Rebecca +14 more
We present the first images of the transition disk around the close binary system HD 34700A in polarized scattered light using the Gemini Planet Imager instrument on Gemini South. The J- and H-band images reveal multiple spiral-arm structures outside a large (R = 0.″49 = 175 au) cavity, along with a bluish spiral structure inside the cavity. The c…
No Evidence for Lunar Transit in New Analysis of Hubble Space Telescope Observations of the Kepler-1625 System
Bedell, Megan; Kreidberg, Laura; Luger, Rodrigo
Observations of the Kepler-1625 system with Kepler and the Hubble Space Telescope have suggested the presence of a candidate exomoon, Kepler-1625b I, a Neptune-radius satellite orbiting a long-period Jovian planet. Here we present a new analysis of the Hubble observations, using an independent data reduction pipeline. We find that the transit ligh…
NICER X-Ray Observations of Seven Nearby Rotation-powered Millisecond Pulsars
Chakrabarty, Deepto; Bogdanov, Slavko; Deneva, Julia S. +18 more
The Neutron star Interior Composition Explorer observed several rotation-powered millisecond pulsars (MSPs) to search for or confirm the presence of X-ray pulsations. When broad and sine-like, these pulsations may indicate thermal emission from hot polar caps at the magnetic poles on the neutron star surface. We report confident detections (≥4.7σ …
Multi-wavelength Properties of Type 1 and Type 2 AGN Host Galaxies in the Chandra-COSMOS Legacy Survey
Lusso, Elisabeta; Marchesi, Stefano; Onodera, Masato +6 more
We investigate the multi-wavelength properties of host galaxies of 3701 X-ray-selected active galactic nuclei (AGNs) out to z ∼ 5 in the Chandra-COSMOS Legacy Survey. Thanks to the extensive multi-wavelength photometry available in the COSMOS field, we derive AGN luminosities, host stellar masses, and star formation rates (SFRs) via a multi-compon…
Dissecting the AGN Disk-Jet System with Joint VLBI-Gaia Analysis
Kovalev, Y. Y.; Plavin, A. V.; Petrov, L. Y.
We analyze differences in positions of active galactic nuclei (AGNs) between Gaia data release 2 and very long baseline interferometry (VLBI) and compare the significant VLBI-to-Gaia offsets in more than 1000 objects with their jet directions. Remarkably at least three-fourths of the significant offsets are confirmed to occur downstream or upstrea…