Search Publications
JWST View of Four Infant Galaxies at z = 8.31–8.49 in the MACS J0416.1‑2403 Field and Implications for Reionization
Grogin, Norman A.; Hathi, Nimish P.; Koekemoer, Anton M. +35 more
New JWST/NIRCam wide-field slitless spectroscopy provides redshifts for four z > 8 galaxies located behind the lensing cluster MACS J0416.1‑2403. Two of them, "Y1" and "JD," have previously reported spectroscopic redshifts based on Atacama Large Millimeter/submillimeter Array measurements of [O III] 88 µm and/or [C II] 157.7 µm line…
The Molecular Clouds of M31
Forbrich, Jan; Lada, Charles J.; Petitpas, Glen +1 more
Deep interferometric observations of CO and dust continuum emission are obtained with the Submillimeter Array at 230 GHz to investigate the physical nature of the giant molecular cloud (GMC) population in the Andromeda galaxy (M31). We use J = 2 ‑ 1 12CO and 13CO emission to derive the masses, sizes, and velocity dispersions …
Magnetar as the Central Engine of AT2018cow: Optical, Soft X-Ray, and Hard X-Ray Emission
Dai, Zi-Gao; Li, Long; Zhong, Shu-Qing +3 more
AT2018cow is the most extensively observed and widely studied fast blue optical transient to date; its unique observational properties challenge all existing standard models. In this paper, we model the luminosity evolution of the optical, soft X-ray, and hard X-ray emission, as well as the X-ray spectrum of AT2018cow with a magnetar-centered engi…
The Magnetic Field in the Colliding Filaments G202.3+2.5
Liu, Tie; Liu, Junhao; Lu, Xing +19 more
We observe the magnetic field morphology toward a nearby star-forming filamentary cloud, G202.3+2.5, using James Clerk Maxwell Telescope/POL-2 850 µm thermal dust polarization observations with an angular resolution of 14.″4 (∼0.053 pc). The average magnetic field orientation is found to be perpendicular to the filaments, while showing diffe…
Discovery of a Dusty Yellow Supergiant Progenitor for the Type IIb SN 2017gkk
Niu, Zexi; Sun, Ning-Chen; Liu, Jifeng
Type IIb supernovae are an important subclass of stripped-envelope supernovae (SNe), which show H lines only at early times. Their progenitors are believed to contain a low-mass H envelope before explosion. This work reports the discovery of a progenitor candidate in preexplosion Hubble Space Telescope images for the Type IIb SN 2017gkk. With deta…
The Kraft Break Sharply Divides Low-mass and Intermediate-mass Stars
White, Russel J.; Beyer, Alexa C.
Main-sequence stars transition at mid-F spectral types from slowly rotating (cooler stars) to rapidly rotating (hotter stars), a transition known as the Kraft Break and attributed to the disappearance of the outer convective envelope, causing magnetic braking to become ineffective. To define this Break more precisely, we assembled spectroscopic me…
A Close Look at Lyα Emitters with JWST/NIRCam at z ≈ 3.1
Jiang, Linhua; Wuyts, Stijn; Huang, Jia-Sheng +2 more
We study 10 spectroscopically confirmed Lyα emitters (LAEs) at z ≈ 3.1 in the Ultra Deep Survey field, covered by the James Webb Space Telescope/NIRCam in the Public Release Imaging for Extragalactic Research program. All LAEs are detected in all NIRCam bands from F090W to F444W, corresponding to rest frame wavelengths of 2200 Å to 1.2 µm. B…
Discovery of a Second Eclipsing, Bursting Neutron Star Low-mass X-Ray Binary in the Globular Cluster Terzan 6
Bahramian, Arash; Homan, Jeroen; Heinke, Craig O. +4 more
We have analyzed Chandra and Suzaku observations of the globular cluster Terzan 6, made when the recurrent transient GRS 1747–312 was in quiescence. Our analysis reveals the presence of a second eclipsing, bursting neutron star low-mass X-ray binary in the central regions of the cluster, in addition to GRS 1747–312. The new source, which we name T…
Physical Parameters and Properties of 20 Cold Brown Dwarfs in JWST
Liu, Jifeng; Wang, Shu; Tu, Zhijun
We present a comprehensive analysis of 20 T and Y dwarfs using spectroscopy from the Near-Infrared Spectrograph (NIRSpec) CLEAR/PRISM and Mid-Infrared Instrument (MIRI) low-resolution spectrometer instruments on the James Webb Space Telescope. To characterize the atmospheric parameters, we utilize two atmospheric model grids: the Sonora Elf Owl an…
Host Galaxy Properties of Gamma-Ray Bursts Involving Neutron Star Binary Mergers and Their Impact on Kilonovae Rates
Im, Myungshin; Jeong, Mankeun
In the upcoming gravitational-wave (GW) observing runs, identifying host galaxies is crucial as it provides essential redshift information and enables the use of GW events as standard sirens. However, pinpointing host galaxies remains challenging due to the large localization uncertainties and the rapidly fading nature of their optical counterpart…