Search Publications
Gravitational wave detection with photometric surveys
Doré, Olivier; Wang, Yijun; Pardo, Kris +1 more
Gravitational wave (GW) detections have considerably enriched our understanding of the universe. To date, all GW events from individual sources have been found by interferometer-type detectors. In this paper, we study a GW detection technique based on astrometric solutions from photometric surveys and demonstrate that it offers a highly flexible f…
A Stable H2O Atmosphere on Europa's Trailing Hemisphere From HST Images
Roth, Lorenz
Previous studies of the global intensities of the oxygen emissions at 1,356 Å and 1,304 Å revealed molecular oxygen (O2) in Europa's atmosphere. Here we investigate the relative changes of the two oxygen emissions when Europa emerges from eclipse as well as the radial profiles of the relative emissions across the sunlit disk in Hubble S…
The Metal-poor Metallicity Distribution of the Ancient Milky Way
Frebel, Anna; Mardini, Mohammad K.; Chiti, Anirudh +1 more
We present a low-metallicity map of the Milky Way consisting of ∼110,000 metal-poor giants with -3.5 < [Fe/H] < -0.75, based on public photometry from the second data release of the SkyMapper survey. These stars extend out to ∼7 kpc from the solar neighborhood and cover the main Galactic stellar populations, including the thick disk and the …
The nature of the extreme X-ray variability in the NLS1 1H 0707-495
Chainakun, P.; Fabian, A. C.; Pinto, C. +11 more
We examine archival XMM-Newton data on the extremely variable narrow-line Seyfert 1 active galactic nucleus (AGN) 1H 0707-495. We construct fractional excess variance (Fvar) spectra for each epoch, including the recent 2019 observation taken simultaneously with eROSITA. We explore both intrinsic and environmental absorption origins for …
Strong lens modelling: comparing and combining Bayesian neural networks and parametric profile fitting
Li, Nan; Dye, Simon; Maresca, Jacob +1 more
The vast quantity of strong galaxy-galaxy gravitational lenses expected by future large-scale surveys necessitates the development of automated methods to efficiently model their mass profiles. For this purpose, we train an approximate Bayesian convolutional neural network (CNN) to predict mass profile parameters and associated uncertainties, and …
Turbulence and wave transmission at an ICME-driven shock observed by the Solar Orbiter and Wind
Kilpua, E. K. J.; Horbury, T. S.; O'Brien, H. +10 more
Aims: An interplanetary coronal mass ejection (ICME) event was observed by the Solar Orbiter at 0.8 AU on 2020 April 19 and by Wind at 1 AU on 2020 April 20. Futhermore, an interplanetary shock wave was driven in front of the ICME. Here, we focus on the transmission of the magnetic fluctuations across the shock and we analyze the characterist…
Icarus: A Flat and Fast Prograde Stellar Stream in the Milky Way Disk
Cignoni, Michele; Lattanzi, Mario G.; Re Fiorentin, Paola +1 more
We explore the local volume of the Milky Way via chemical and kinematical measurements from high-quality astrometric and spectroscopic data recently released by the Gaia, APOGEE, and GALAH programs. We chemically select 1137 stars up to 2.5 kpc of the Sun and [Fe/H] ≤ -1.0 dex, and find evidence of statistically significant substructures. Clusteri…
Measurements of Coronal Magnetic Field Strengths in Solar Active Region Loops
Landi, Enrico; Warren, Harry P.; Brooks, David H.
The characteristic electron densities, temperatures, and thermal distributions of 1 MK active region loops are now fairly well established, but their coronal magnetic field strengths remain undetermined. Here we present measurements from a sample of coronal loops observed by the Extreme-ultraviolet Imaging Spectrometer on Hinode. We use a recently…
The Influence of Age on the Relative Frequency of Super-Earths and Sub-Neptunes
David, Trevor J.; Contardo, Gabriella; Sandoval, Angeli
There is growing evidence that the population of close-in planets discovered by the Kepler mission was sculpted by atmospheric loss, though the typical timescale for this evolution is not well-constrained. Among a highly complete sample of planet hosts of varying ages the age-dependence of the relative fraction of super-Earth and sub-Neptune detec…
Giant white-light flares on fully convective stars occur at high latitudes
Davenport, James R. A.; Pineda, J. Sebastian; Poppenhaeger, Katja +7 more
White-light flares are magnetically driven localized brightenings on the surfaces of stars. Their temporal, spectral, and statistical properties present a treasury of physical information about stellar magnetic fields. The spatial distributions of magnetic spots and associated flaring regions help constrain dynamo theories. Moreover, flares are th…