Search Publications
A Giant Intragroup Nebula Hosting a Damped {Ly}\alpha Absorber at z = 0.313
Johnson, Sean D.; Zahedy, Fakhri S.; Chen, Hsiao-Wen +5 more
This Letter reports the discovery of spatially extended line-emitting nebula, reaching to ≈100 physical kpc (pkpc) from a damped {Ly}α absorber (DLA) at z DLA = 0.313 along the sightline toward quasi-stellar object (QSO) PKS 1127-145 (z QSO = 1.188). This DLA was known to be associated with a galaxy group of dynamical mass M …
Chemical Abundance Signature of J0023+0307: A Second-generation Main-sequence Star with [Fe/H] < -6
Hansen, Terese T.; Ezzeddine, Rana; Frebel, Anna +4 more
We present a chemical abundance analysis of the faint halo metal-poor main-sequence star J0023+0307, with [Fe/H] < -6.3, based on a high-resolution (R ∼ 35,000) Magellan/MIKE spectrum. The star was originally found to have [Fe/H] < -6.6 based on a Ca II K measurement in an R ∼ 2500 spectrum. No iron lines could be detected in our MIKE spectr…
Magnetic Turbulence Spectra and Intermittency in the Heliosheath and in the Local Interstellar Medium
Pogorelov, Nikolai V.; Fraternale, Federico; Richardson, John D. +1 more
The understanding of inertial-scale dynamics in the heliosheath is not yet thorough. Magnetic field fluctuations across the inner heliosheath (IHS) and the local interstellar medium (LISM) are here considered to provide accurate and highly resolved statistics over different plasma conditions between 88 and 136 au. By using the unique in situ 48 s …
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…