Search Publications
The Most Obscured AGNs in the XMM-SERVS Fields
Brandt, W. N.; Zou, Fan; Bauer, Franz E. +9 more
We perform X-ray spectral analyses to derive the characteristics (e.g., column density, X-ray luminosity) of ≈10,200 active galactic nuclei (AGNs) in the XMM-Spitzer Extragalactic Representative Volume Survey, which was designed to investigate the growth of supermassive black holes across a wide dynamic range of cosmic environments. Using physical…
Unusually long path length for a nearly scatter-free solar particle event observed by Solar Orbiter at 0.43 au
Kouloumvakos, Athanasios; Xu, Zigong; Wimmer-Schweingruber, Robert F. +28 more
Context. After their acceleration and release at the Sun, solar energetic particles (SEPs) are injected into the interplanetary medium and are bound to the interplanetary magnetic field (IMF) by the Lorentz force. The expansion of the IMF close to the Sun focuses the particle pitch-angle distribution, and scattering counteracts this focusing. Sola…
An excursion into the core of the cluster lens Abell 1689
Scarlata, Claudia; Liesenborgs, Jori; Alavi, Anahita +3 more
Abell 1689 is a well-studied cluster of galaxies and one of the largest gravitational lens systems ever observed. We have obtained a reconstruction of the cluster Abell 1689 using GRALE, a free-form lens inversion method that relies exclusively on the multiple image data. Non-inclusion of any data related to cluster member galaxies ensures an unbi…
The Closest View of a Fast Coronal Mass Ejection: How Faulty Assumptions Near Perihelion Lead to Unrealistic Interpretations of PSP/WISPR Observations
Reeves, Katharine K.; Hess, Phillip; West, Matthew J. +3 more
We report on the closest view of a coronal mass ejection (CME) observed by the Parker Solar Probe (PSP)/ Wide-field Imager for Parker Solar PRobe (WISPR) instrument on 2022 September 5, when PSP was traversing from a distance of 15.3 to 13.5 R ⊙ from the Sun. The CME leading edge and an arc-shaped concave-up structure near the core were…
A z = 1.85 galaxy group in CEERS: Evolved, dustless, massive intra-halo light and a brightest group galaxy in the making
Papovich, Casey; Finkelstein, Steven L.; Pérez-González, Pablo G. +25 more
We present CEERS JWST/NIRCam imaging of a massive galaxy group at z = 1.85, to explore the early JWST view on massive group formation in the distant Universe. The group contains ≳16 members (including six spectroscopic confirmations) down to log10(M⋆/M⊙) = 8.5, including the brightest group galaxy (BGG) in the proc…
Discovery of delta Scuti variables in eclipsing binary systems II. Southern TESS field search
Kahraman Aliçavuş, F.; Aliçavuş, F.; Çoban, Ç. G. +3 more
The presence of pulsating stars in eclipsing binary systems (EBs) makes these objects significant since they allow us to investigate the stellar interior structure and evolution. Different types of pulsating stars could be found in EBs, such as δ Scuti variables. δ Scuti stars in EBs have been known for decades, and the increasing number of such s…
Spectroscopic follow-up of statistically selected extremely metal-poor star candidates from GALAH DR3
Spitler, Lee R.; Da Costa, G. S.; Buder, Sven +5 more
The advent of large-scale stellar spectroscopic surveys naturally leads to the implementation of machine learning techniques to isolate, for example, small sub-samples of potentially interesting stars from the full data set. A recent example is the application of the t-SNE statistical method to ~600 000 stellar spectra from the GALAH survey in ord…
Accelerated phase-mixing in the stellar halo due to a rotating bar
Vasiliev, Eugene; Belokurov, Vasily; Davies, Elliot Y. +1 more
In a galaxy merger, the stars tidally stripped from the satellite and accreted onto the host galaxy undergo phase-mixing and form finely grained structures in the phase space. However, these fragile structures may be destroyed in the subsequent galaxy evolution, in particular, by a rotating bar that appears well after the merger is completed. In t…
Multiwavelength study of NGC 1365: The obscured active nucleus and off-nuclear compact X-ray sources
Shalima, P.; Swain, Subhashree; Dewangan, Gulab Chand +2 more
We present a multiwavelength study of the active nucleus and the off-nuclear X-ray sources in the nearby spiral galaxy, NGC 1365 using three simultaneous UV/X-ray observations by AstroSat over a two months period and archival IR observations performed with Spitzer and Herschel. Utilizing the data from the Soft X-ray Telescope (SXT) onboard AstroSa…
New stellar velocity substructures from Gaia DR3 proper motions
McMillan, Paul J.; Hobbs, David; Mikkola, Daniel
Local stellar motions are expected, and have been shown, to include signatures of the Galaxy's past dynamical evolution. These are typically divided into the disc, which shows the dynamical effects of spiral arms and the bar, and the stellar halo, with structures thought to be debris from past mergers. We use Gaia Data Release 3 to select large sa…