Search Publications
Change-point Detection and Image Segmentation for Time Series of Astrophysical Images
Zezas, Andreas; Xu, Cong; Kashyap, Vinay L. +2 more
Many astrophysical phenomena are time-varying, in the sense that their intensity, energy spectrum, and/or the spatial distribution of the emission suddenly change. This paper develops a method for modeling a time series of images. Under the assumption that the arrival times of the photons follow a Poisson process, the data are binned into 4D grids…
FUV and NIR size of the HI selected low surface brightness galaxies
Cheng, Cheng; Li, Zi-Jian; Huang, Jia-Sheng +10 more
How low surface brightness galaxies (LSBGs) form stars and assemble stellar mass is one of the most important questions related to understanding the LSBG population. We select a sample of 381 HI bright LSBGs with both far ultraviolet (FUV) and near infrared (NIR) observations to investigate the star formation rate (SFR) and stellar mass scales, an…
A survey of IRAS young stellar object candidates. Searching for large-scale Herbig-Haro objects
Estalella, Robert; Riera, Angels; López, Rosario +1 more
Context. Jets and outflows are associated with young stellar objects across the stellar mass spectrum, from brown dwarf protostars to massive Ae/Be stars. Frequently the jet morphology is spatially discontinuous because of the temporal variability of the ejection from the driving source. Images covering a wide field of view around the jet-driving …
Anomalous Hydrogen Recombination Line Ratios in Ultraluminous Infrared Galaxies
Nakagawa, Takao; Baba, Shunsuke; Isobe, Naoki +5 more
We conducted systematic observations of the H I Brα (4.05 µm) and Brβ (2.63 µm) lines in 52 nearby (z < 0.3) ultraluminous infrared galaxies (ULIRGs) with AKARI. Among 33 ULIRGs wherein the lines are detected, 3 galaxies show anomalous Brβ/Brα line ratios (~1.0), which are significantly higher than those for case B (0.565). Our obse…
Significant H I and Metal Differences around the z = 0.83 Lens Galaxy toward the Doubly Lensed Quasar SBS 0909+532
Kulkarni, Varsha P.; Lopez, Sebastian; Cashman, Frances H.
We report a large difference in neutral hydrogen (H I) and metal column densities between the two sight lines probing opposite sides of the lensing galaxy at zlens = 0.83 toward the doubly lensed quasar SBS 0909+532. Using archival HST-STIS and Keck HIRES spectra of the lensed quasar images, we measure log NH I = 18.77 ± 0.12…
Spatial distribution of the aromatic and aliphatic carbonaceous nanograin features in the protoplanetary disk around HD 100546
Pantin, E.; Ysard, N.; Habart, E. +4 more
Context. Carbonaceous nanograins are present at the surface of protoplanetary disks around Herbig Ae/Be stars, where most of the ultraviolet energy from the central star is dissipated. Efficiently coupled to the gas, they are unavoidable to understand the physics and chemistry of these disks. Furthermore, nanograins are able to trace the outer fla…
A Complete Data Set of Equatorial Projections of Saturn's Energetic Neutral Atom Emissions Observed by Cassini-INCA
Mitchell, D. G.; Paranicas, C.; Badman, S. V. +3 more
Observations of energetic neutral atoms (ENAs) are a useful tool for analyzing ion and neutral abundances in planetary magnetospheres. They are created when hot plasma, originating for example from magnetic reconnection sites, charge-exchanges with the ambient neutral population surrounding the planet. The motion of ENAs is not governed by the mag…
Spatial distribution of the X-ray-emitting plasma of U Geminorum in quiescence and outburst
Maeda, Yoshitomo; Ishida, Manabu; Hayashi, Takayuki +2 more
We present our analysis of the Suzaku data of U Geminorum (U Gem) from 2012 both in quiescence and outburst. Unlike SS Cygni (SS Cyg), the hard X-ray flux of U Gem is known to increase at times of optical outburst. A sophisticated spectral model and reliable distance estimate now reveal that this can be attributed to the fact that the mass accreti…
Molecular Gas in the Nuclear Region of NGC 6240
Bally, John; Glenn, Jason; Rangwala, Naseem +3 more
NGC 6240 is a luminous infrared galaxy in the local universe in the midst of a major merger. We analyze high-resolution interferometric observations of warm molecular gas using CO J = 3-2 and 6-5 in the central few kpc of NGC 6240 taken by the Atacama Large Millimeter Array. Using these CO line observations, we model the density distribution and k…
Imaging results from the legacy Giant Metrewave Radio Telescope Galaxy Cluster Key Project
Kale, Ruta; Wadadekar, Yogesh; George, Lijo T.
We have used archival Giant Metrewave Radio Telescope (GMRT) data to image and study 39 galaxy clusters. These observations were made as part of the GMRT Key Project on galaxy clusters between 2001 and 2004. The observations presented in this sample include 14 observations at 610 MHz, 29 at 325 MHz, and three at 244 MHz covering a redshift range o…