Search Publications
A Tale of Three Dwarfs: No Extreme Cluster Formation in Extreme Star-forming Galaxies
Whitmore, Bradley C.; Chandar, Rupali; Ubeda, Leonardo +8 more
Nearly all current simulations predict that outcomes of the star formation process, such as the fraction of stars that form in bound clusters (Γ), depend on the intensity of star formation activity (ΣSFR) in the host galaxy. The exact shape and strength of the predicted correlations, however, vary from simulation to simulation. Observat…
Dimming of Continuum Captured in Mrk 841: New Clues on the Nature of the Soft X-Ray Excess
Kriss, Gerard A.; Mehdipour, Missagh; Mao, Junjie +2 more
We report on a remarkable change in the spectral energy distribution (SED) of Mrk 841, providing new insights on how the soft X-ray excess emission in active galactic nuclei (AGNs) is produced. By Swift monitoring of a sample of Seyfert-1 galaxies, we found an X-ray spectral hardening event in Mrk 841. We thereby triggered our XMM-Newton, NuSTAR, …
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…
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…
PEARLS: Low Stellar Density Galaxies in the El Gordo Cluster Observed with JWST
Grogin, Norman A.; Koekemoer, Anton M.; Pirzkal, Nor +23 more
A full understanding of how unusually large ultradiffuse galaxies (UDGs) fit into our conventional theory of galaxy formation remains elusive, despite the large number of objects identified locally. A natural extension of UDG research is the study of similar galaxies at higher redshift to establish how their properties may evolve over time. Howeve…
A 2:1 Mean-motion Resonance Super-Jovian Pair Revealed by TESS, FEROS, and HARPS
Trifonov, Trifon; Henning, Thomas; Latham, David W. +24 more
We report the discovery of a super-Jovian 2:1 mean-motion resonance (MMR) pair around the G-type star TIC 279401253, whose dynamical architecture is a prospective benchmark for planet formation and orbital evolution analysis. The system was discovered thanks to a single-transit event recorded by the Transiting Exoplanet Survey Satellite mission, w…
Examining the Rotation Period Distribution of the 40 Myr Tucana-Horologium Association with TESS
Kiman, Rocio; Faherty, Jacqueline K.; Gagné, Jonathan +6 more
The Tucana-Horologium association (Tuc-Hor) is a 40 Myr old moving group in the southern sky. In this work, we measure the rotation periods of 313 Tuc-Hor objects with TESS light curves derived from TESS full-frame images and membership lists driven by Gaia EDR3 kinematics and known youth indicators. We recover a period for 81.4% of the sample and…
Strong and Rapid X-Ray Variability of the Super-Eddington Accreting Quasar SDSS J081456.10+532533.5
Brandt, W. N.; Garmire, Gordon P.; Luo, Bin +6 more
We report strong and rapid X-ray variability found from the super-Eddington accreting quasar SDSS J081456.10+532533.5 at z = 0.1197. It has a black hole mass of 2.7 × 107 M ⊙ and a dimensionless accretion rate of ≈4 measured from reverberation-mapping observations. It showed weak X-ray emission in the 2021 February Chandra ob…
Denoising Diffusion Probabilistic Models to Predict the Density of Molecular Clouds
Xu, Duo; Tan, Jonathan C.; Hsu, Chia-Jung +1 more
We introduce the state-of-the-art deep-learning denoising diffusion probabilistic model as a method to infer the volume or number density of giant molecular clouds (GMCs) from projected mass surface density maps. We adopt magnetohydrodynamic simulations with different global magnetic field strengths and large-scale dynamics, i.e., noncolliding and…
Photometric Calibrations of M-dwarf Metallicity with Markov Chain Monte Carlo and Bayesian Inference
Caballero, J. A.; Montes, D.; Duque-Arribas, C. +3 more
Knowledge of stellar atmospheric parameters (T eff, $\mathrm{log}g$ , [Fe/H]) of M dwarfs can be used to constrain both theoretical stellar models and Galactic chemical evolutionary models, and guide exoplanet searches, but their determination is difficult due to the complexity of the spectra of their cool atmospheres. In our ongoing ef…