Search Publications
Predicting Solar Flares Using CNN and LSTM on Two Solar Cycles of Active Region Data
Chen, Yang; Gombosi, Tamas; Bobra, Monica G. +5 more
We consider the flare prediction problem that distinguishes flare-imminent active regions that produce an M- or X-class flare in the succeeding 24 hr, from quiet active regions that do not produce any flares within ±24 hr. Using line-of-sight magnetograms and parameters of active regions in two data products covering Solar Cycles 23 and 24, we tra…
Evolution of a Relativistic Outflow and X-Ray Corona in the Extreme Changing-look AGN 1ES 1927+654
Fabian, Andrew C.; Remillard, Ronald A.; Ricci, Claudio +8 more
1ES 1927+654 is a paradigm-defying active galactic nucleus (AGN) and one of the most peculiar X-ray nuclear transients. In early 2018, this well-known AGN underwent a changing-look event, in which broad optical emission lines appeared and the optical flux increased. Yet, by 2018 July, the X-ray flux had dropped by over two orders of magnitude, ind…
CO Line Emission Surfaces and Vertical Structure in Midinclination Protoplanetary Disks
Wilner, David J.; Ilee, John D.; Andrews, Sean M. +18 more
High spatial resolution CO observations of midinclination (≈30°-75°) protoplanetary disks offer an opportunity to study the vertical distribution of CO emission and temperature. The asymmetry of line emission relative to the disk major axis allows for a direct mapping of the emission height above the midplane, and for optically thick, spatially re…
Metallicities of Five z > 5 Emission-line Galaxies in SMACS 0723 Revealed by JWST
Barger, A. J.; Cowie, L. L.; Taylor, A. J.
JWST's Early Release Observations of the lensing cluster SMACS J0723.3-7327 have given an unprecedented spectroscopic look into the high-redshift universe. These observations reveal five galaxies at z > 5. All five have detectable [O III]λ4363 line emission, indicating that these galaxies have high temperatures and low metallicities and that th…
JWST Sneaks a Peek at the Stellar Morphology of z 2 Submillimeter Galaxies: Bulge Formation at Cosmic Noon
Smail, Ian; Chen, Chian-Chou; Wang, Wei-Hao +6 more
We report morphological analyses of seven submillimeter galaxies (SMGs) at z ~ 2 using the James Webb Space Telescope NIRCam images taken as part of the public CEERS and PRIMER surveys. Through two-dimensional surface brightness profile fitting we find evidence of compact reddened stellar structures in all the SMGs, in particular in the F444W filt…
Evidence for Cold-stream to Hot-accretion Transition as Traced by Lyα Emission from Groups and Clusters at 2 < z < 3.3
Finoguenov, A.; Daddi, E.; Elbaz, D. +12 more
We present Keck Cosmic Web Imager observations of giant Lyα halos surrounding nine galaxy groups and clusters at 2 < z < 3.3, including five new detections and one upper limit. We find observational evidence for the cold-stream to hot-accretion transition predicted by theory by measuring a decrease in the ratio between the spatially extended…
Further Evidence of Modified Spin-down in Sun-like Stars: Pileups in the Temperature-Period Distribution
Angus, Ruth; van Saders, Jennifer L.; Zinn, Joel C. +5 more
We combine stellar surface rotation periods determined from NASA's Kepler mission with spectroscopic temperatures to demonstrate the existence of pileups at the long-period and short-period edges of the temperature-period distribution for main-sequence stars with temperatures exceeding ~5500 K. The long-period pileup is well described by a curve o…
No Redshift Evolution of Galaxies' Dust Temperatures Seen from 0 < z < 2
Casey, Caitlin M.; Drew, Patrick M.
Some recent literature has claimed there to be an evolution in galaxies' dust temperatures toward warmer (or colder) spectral energy distributions (SEDs) between low and high redshift. These conclusions are driven by both theoretical models and empirical measurement. Such claims sometimes contradict one another and are prone to biases in samples o…
On the Role of Coronal Shocks for Accelerating Solar Energetic Electrons
Kouloumvakos, Athanasios; Dresing, Nina; Vainio, Rami +1 more
We study the role of coronal mass ejection (CME) driven shocks in the acceleration of solar energetic electrons. Using observations by the two STEREO spacecraft, we correlate electron peak intensities of solar energetic particle events measured in situ with various parameters of the associated coronal shocks. These shock parameters were derived by…
The Number Densities and Stellar Populations of Massive Galaxies at 3 < z < 6: A Diverse, Rapidly Forming Population in the Early Universe
Muzzin, Adam; Forrest, Ben; Marchesini, Danilo +9 more
We present the census of massive (log(M */M ⊙) > 11) galaxies at 3 < z < 6 identified over the COSMOS/UltraVISTA Ultra-Deep field stripes: consisting of ≈100 and ≈20 high-confidence candidates at 3 < z < 4 and 4 < z < 6, respectively. The 3 < z < 4 population is comprised of post-starburst, UV-star-…