Search Publications
The Role of Dust, UV Luminosity and Large-scale Environment on the Escape of Lyα Photons: A Case Study of a Protocluster Field at z = 3.1
Dey, Arjun; Lee, Kyoung-Soo; Huang, Yun +3 more
We present a detailed characterization of the Lyα properties for 93 Lyα emitters (LAEs) at z ~ 3.1 selected from the D1 field of the Canada-France-Hawaii Telescope Legacy Survey, including 24 members of a massive protocluster. The median-stacked Lyα image shows an extended Lyα halo (LAH) surrounding the galaxy with the exponential scale length 4.9…
A new framework for understanding systematic errors in cluster lens modelling - II. Constraint selection
Keeton, Charles R.; Raney, Catie A.; Zimmerman, Dhruv T.
Cluster lens models are affected by a variety of choices in the lens modelling process. We have begun a programme to develop a systematic error budget for cluster lens modelling. Here, we examine the selection of image constraints as a potential systematic effect. For constraining the mass model, we find that it is more important to have images be…
Cold Ionospheric Ions in the Magnetosphere
André, Mats; Toledo-Redondo, Sergio; Yau, Andrew W.
Cold (eV) ions of ionospheric origin are a major source of magnetospheric plasma. These ions dominate the number density for most of the volume of the magnetosphere, most of the time. This affects large-scale physics, including plasma temperature and pressure (and thus instability thresholds) and the Alfvén velocity (and thus energy transport with…
Observational Kinematic Characteristics of Blobs in Solar Coronal Helmet and Pseudo Streamers
Kumar, Pankaj; Cho, Kyung-Suk; Kim, Yeon-Han +4 more
We examine two helmet and two pseudo streamers (HSs and PSs) observed on 2018 and 2019. The HSs (PSs) have dark coronal cavities and stretched loop structures (twin coronal cavities and narrow plasma sheet) at their bases, which are well observed in K-Coronagraph (K-Cor). Their outer-corona structures (top of core, cusp, and stalk) are also clearl…
The Highly Self-absorbed Blazar PKS 1351-018
Frey, Sándor; Chen, Sina; Punsly, Brian +5 more
PKS 1351-018 at a redshift of z = 3.71 is one of the most luminous, steady synchrotron sources with a luminosity >1047 erg s-1. The synchrotron luminosity does not seem to have varied by more than ~25% over 35 yr. In order to appreciate this remarkable behavior, if it were at z = 0.5, it would have a flux density at 15 GHz…
Redshift evolution of X-ray spectral index of quasars observed by XMM-NEWTON/SDSS
Misra, R.; Hayman, Z. M.; Shehata, SH. M. +2 more
We study the X-ray spectral evolution of quasars with red-shift using a sample of 1280 quasars constructed by cross-referencing the XMM-Newton 3 XMM - DR 7 and the optical SDSS-DR14 catalogues. The sources were selected to have a minimum detected X-ray counts >600 and which were not affected by high background. The sample redshift distribution …
Exploring the Sun's upper atmosphere with neural networks: Reversed patterns and the hot wall effect
Asensio Ramos, A.; Socas-Navarro, H.
We have developed an inversion procedure designed for high-resolution solar spectro-polarimeters, such as those of Hinode and the DKIST. The procedure is based on artificial neural networks trained with profiles generated from random atmospheric stratifications for a high generalization capability. When applied to Hinode data, we find a hot fine-s…
AT 2019qyl in NGC 300: Internal Collisions in the Early Outflow from a Very Fast Nova in a Symbiotic Binary
Boyer, Martha L.; Kilpatrick, Charles D.; Coulter, David A. +39 more
Nova eruptions, thermonuclear explosions on the surfaces of white dwarfs (WDs), are now recognized to be among the most common shock-powered astrophysical transients. We present the early discovery and rapid ultraviolet (UV), optical, and infrared (IR) temporal development of AT 2019qyl, a recent nova in the nearby Sculptor Group galaxy NGC 300. T…
Fitting procedure for estimating interstellar extinction at high galactic latitudes
Malkov, Oleg; Kovaleva, Dana; Avdeeva, Aleksandra +1 more
We determine the interstellar extinction in the selected high-latitude areas of the sky based on Gaia EDR3 astrometry and photometry and spectroscopic data from RAVE survey. We approximate the results with the cosecant law in each area thus deriving the parameters of the barometric formula for different lines of sight. The distribution of the para…
Variability in Protoplanetary Nebulae. VIII. A New Sample of Southern Hemisphere Objects
Lu, Wenxian; Hrivnak, Bruce J.; Henson, Gary +5 more
As part of our continuing study of light variability in protoplanetary nebulae (PPNe), we present the results from a long-term study of nine southern hemisphere objects. We have monitored their light variations over a nine-year interval from 2010 to 2018. These were supplemented by data from the ASAS-SN and ASAS-3 surveys, leading to combined ligh…