Search Publications
An Infrared Census of DUST in Nearby Galaxies with Spitzer (DUSTiNGS). V. The Period-Luminosity Relation for Dusty Metal-poor AGB Stars
van Loon, J. Th.; Gehrz, R. D.; Skillman, E. D. +10 more
The survey for DUST in Nearby Galaxies with Spitzer (DUSTiNGS) has identified hundreds of candidate dust-producing asymptotic giant branch (AGB) stars in several nearby metal-poor galaxies. We have obtained multi-epoch follow-up observations for these candidates with the Spitzer Space Telescope and measured their infrared (IR) light curves. This h…
Testing Feedback-regulated Star Formation in Gas-rich, Turbulent Disk Galaxies
Bolatto, A. D.; Fisher, D. B.; Glazebrook, K. +3 more
In this paper we compare the molecular gas depletion times and midplane hydrostatic pressure in turbulent, star-forming disk galaxies to internal properties of these galaxies. For this analysis we use 17 galaxies from the DYNAMO sample of nearby (z ∼ 0.1) turbulent disks. We find a strong correlation, such that galaxies with lower molecular gas de…
H 0 Tension and the Phantom Regime: A Case Study in Terms of an Infrared f(T) Gravity
El-Zant, Amr; El Hanafy, Waleed; Elgammal, Sherif
We propose an f(T) teleparallel gravity theory including a torsional infrared (IR) correction. We show that the governing Friedmann’s equations of a spatially flat universe include a phantom-like effective dark energy term sourced by the torsion IR correction. As has been suggested, this phantom phase does indeed act to reconcile the tension betwe…
Simultaneous Kepler/K2 and XMM-Newton observations of superflares in the Pleiades
Antoniou, V.; Micela, G.; Stauffer, J. +10 more
Context. Flares are powerful events ignited by a sudden release of magnetic energy which triggers a cascade of interconnected phenomena, each resulting in emission in different electromagnetic bands. In fact, in the Sun flares are observed across the whole electromagnetic spectrum. Multi-band observations of stellar flares are instead rare. This l…
The ASAS-SN catalogue of variable stars - IV. Periodic variables in the APOGEE survey
Kochanek, C. S.; Stanek, K. Z.; Thompson, Todd A. +12 more
We explore the synergy between photometric and spectroscopic surveys by searching for periodic variable stars among the targets observed by the Apache Point Observatory Galactic Evolution Experiment (APOGEE) using photometry from the All-Sky Automated Survey for Supernovae (ASAS-SN). We identified 1924 periodic variables among more than 258 000 AP…
Constraining the Magnetic Field in the TeV Halo of Geminga with X-Ray Observations
Liu, Ruo-Yu; Ge, Chong; Wang, Xiang-Yu +1 more
Recently, the High Altitude Water Cherenkov (HAWC) collaboration reported the discovery of a TeV halo around the Geminga pulsar. The TeV emission is believed to originate from the inverse Compton scattering of pulsar-injected electrons/positrons off cosmic microwave background photons. During this time, these electrons should inevitably radiate X-…
Chemical and Kinematic Properties of the Galactic Disk from the LAMOST and Gaia Sample Stars
Shi, Jianrong; Chen, Yuqin; Ma, Jun +5 more
We determined the chemical and kinematic properties of the Galactic thin and thick disk using a sample of 307,246 A/F/G/K-type giant stars from the LAMOST spectroscopic survey and Gaia DR2 survey. Our study found that the thick disk globally exhibits no metallicity radial gradient, but the inner disk (R ≤ 8 kpc) and the outer disk (R > 8 kpc) h…
Investigating the X-ray enhancements of highly radio-loud quasars at z > 4
Brandt, W. N.; Garmire, G. P.; Miller, B. P. +2 more
We have investigated the jet-linked X-ray emission from highly radio-loud quasars (HRLQs; log R > 2.5) at high redshift. We studied the X-ray properties of 15 HRLQs at z > 4, using new Chandra observations for six objects and archival XMM-Newton and Swift observations for the other nine. We focused on testing the apparent enhancement of jet-…
Testing the Evolutionary Link between Type 1 and Type 2 Quasars with Measurements of the Interstellar Medium
Ho, Luis C.; Shangguan, Jinyi
In a popular scenario for the coevolution of massive black holes and galaxies, major mergers of gas-rich galaxies fuel vigorous star formation and obscured (type 2) quasar activity until energy feedback from the active galactic nucleus (AGN) clears away the gas and dust to reveal an unobscured (type 1) quasar. Under this scenario, the precursor ty…
Constraints on the Occurrence and Distribution of 1-20 M Jup Companions to Stars at Separations of 5-5000 au from a Compilation of Direct Imaging Surveys
Gagné, Jonathan; Delorme, Philippe; Lafrenière, David +4 more
We present the first statistical analysis of exoplanet direct imaging surveys combining adaptive optics (AO) imaging at small separations with deep seeing-limited observations at large separations allowing us to study the entire orbital separation domain from 5 to 5000 au simultaneously. Our sample of 344 stars includes only confirmed members of n…