Search Publications
Discovery of a Very Hot Phase of the Milky Way Circumgalactic Medium with Non-solar Abundance Ratios
Nicastro, Fabrizio; Mathur, Smita; Das, Sanskriti +1 more
We present the discovery of a very hot gas phase of the Milky Way circumgalactic medium (CGM) at T ≈ 107 K, using deep XMM-Newton Reflection Grating Spectrometer observations of the blazar 1ES 1553+113. The hot gas, coexisting with a warm-hot phase at T ≈ 106 K is α-enhanced, with [{{O}}/{Fe}]={0.9}-0.3+0.7
ALMA and HST Kiloparsec-scale Imaging of a Quasar-galaxy Merger at Z ≈ 6.2
Carilli, Chris; Strauss, Michael A.; Fan, Xiaohui +12 more
We present kiloparsec-scale Atacama Large Millimeter/submillimeter Array (ALMA) and Hubble Space Telescope imaging of the quasar PJ308-21 at z = 6.2342, tracing dust, gas (via the [C II] 158 µm line), and young stars. At a resolution of ∼0.″3 (≈1.7 kpc), the system is resolved over >4″ (>20 kpc). In particular, it features a main compo…
Turning Gravitationally Lensed Supernovae into Cosmological Probes
Rodney, S.; Pierel, J. D. R.
Recently, there have been two landmark discoveries of gravitationally lensed supernovae: the first multiply imaged SN, “Refsdal”, and the first Type Ia SN resolved into multiple images, SN iPTF16geu. Fitting the multiple light curves of such objects can deliver measurements of the lensing time delays, which are the difference in arrival times for …
CO Emission in Infrared-selected Active Galactic Nuclei
Kirkpatrick, Allison; Pope, Alexandra; Keller, Erica +1 more
In order to better understand how active galactic nuclei (AGNs) affect the interstellar media of their host galaxies, we perform a meta-analysis of the CO emission for a sample of z = 0.01-4 galaxies from the literature with existing CO detections and well-constrained AGN contributions to the infrared (67 galaxies). Using either Spitzer/IRS mid-in…
Spatially Resolved Stellar Kinematics of the Ultra-diffuse Galaxy Dragonfly 44. II. Constraints on Fuzzy Dark Matter
van Dokkum, Pieter; Forbes, Duncan A.; Romanowsky, Aaron J. +9 more
Given the absence of directly detected dark matter (DM) as weakly interacting massive particles, there is strong interest in the possibility that DM is an ultralight scalar field, here denoted as “fuzzy” DM. Ultra-diffuse galaxies, with the sizes of giant galaxies and the luminosities of dwarf galaxies, have a wide range of DM halo masses, thus pr…
Contributions from Accreted Organics to Titan’s Atmosphere: New Insights from Cometary and Chondritic Data
Miller, Kelly E.; Glein, Christopher R.; Waite, J. Hunter, Jr.
Since its discovery in the first half of the 20th century, scientists have puzzled over the origins of Titan’s atmosphere. Current models suggest that atmospheric N2 on Titan may have originated from NH3-bearing ice with N-isotopic ratios similar to those observed in NH2 in cometary comae (14N/15
In Situ Measurements of the Variable Slow Solar Wind near Sector Boundaries
Davies, J. A.; Lavraud, B.; Kilpua, E. +2 more
The release of density structures at the tip of the coronal helmet streamers, likely as a consequence of magnetic reconnection, contributes to the mass flux of the slow solar wind (SSW). In situ measurements in the vicinity of the heliospheric plasma sheet of the magnetic field, protons, and suprathermal electrons reveal details of the processes a…
A New Class of Large-amplitude Radial-mode Hot Subdwarf Pulsators
Duev, Dmitry A.; Riddle, Reed; Szkody, Paula +22 more
Using high-cadence observations from the Zwicky Transient Facility at low Galactic latitudes, we have discovered a new class of pulsating, hot compact stars. We have found four candidates, exhibiting blue colors (g - r ≤ -0.1 mag), pulsation amplitudes of >5%, and pulsation periods of 200-475 s. Fourier transforms of the light curves show only …
The Star Formation History in the Solar Neighborhood as Told by Massive White Dwarfs
Isern, Jordi
White dwarfs (WDs) are the remnants of low- and intermediate-mass stars. Because of electron degeneracy, their evolution is just a simple gravothermal process of cooling. Recently, thanks to Gaia data, it has been possible to construct the luminosity function of massive (0.9≤slant M/{M}⊙ ≤slant 1.1) WDs in the solar neighborhood (d< …
The Fraction of Active Galactic Nuclei in the USS 1558-003 Protocluster at z = 2.53
Miller, Eric D.; Koyama, Yusei; Kodama, Tadayuki +8 more
The incidence of active galactic nuclei (AGNs) within the local environment is a potentially valuable probe of the mechanisms that trigger and provide fuel for accretion onto supermassive black holes. While the correlation between AGN fraction and environment has been well-studied in the local universe, AGN fractions have been measured for relativ…