Search Publications
Determination of the Mass of IGR J17091-3624 from "Spectro-temporal" Variations during the Onset Phase of the 2011 Outburst
Nandi, A.; Mandal, S.; Iyer, N.
The 2011 outburst of the black hole candidate IGR J17091-3624 followed the canonical track of state transitions along with the evolution of quasi-periodic oscillation (QPO) frequencies before it began exhibiting various variability classes similar to GRS 1915+105. We use this canonical evolution of spectral and temporal properties to determine the…
The Spatial Distribution of the Young Stellar Clusters in the Star-forming Galaxy NGC 628
Cignoni, M.; Dale, D. A.; Calzetti, D. +21 more
We present a study of the spatial distribution of the stellar cluster populations in the star-forming galaxy NGC 628. Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury Program LEGUS (Legacy ExtraGalactic UV Survey), we have identified 1392 potential young (≲ 100 Myr) stellar clusters within the galaxy using a…
Multiwavelength Observations of a Partially Eruptive Filament on 2011 September 8
Feng, L.; Cheng, X.; Guo, Y. +5 more
In this paper, we report our multiwavelength observations of a partial filament eruption event in NOAA active region (AR) 11283 on 8 September 2011. A magnetic null point and the corresponding spine and separatrix surface are found in the AR. Beneath the null point, a sheared arcade supports the filament along the highly complex and fragmented pol…
The High-mass Stellar Initial Mass Function in M31 Clusters
Bell, Eric F.; Dolphin, Andrew E.; Skillman, Evan D. +16 more
We have undertaken the largest systematic study of the high-mass stellar initial mass function (IMF) to date using the optical color-magnitude diagrams (CMDs) of 85 resolved, young (4 {Myr}\lt t\lt 25 {Myr}), intermediate mass star clusters (103-104 M⊙), observed as part of the Panchromatic Hubble Andromeda Treasur…
Broadband Observations of the Compton-thick Nucleus of NGC 3393
Harrison, F. A.; Stern, D.; Treister, E. +16 more
We present new Nuclear Spectroscopic Telescope Array (NuSTAR ) and Chandra observations of NGC 3393, a galaxy reported to host the smallest separation dual active galactic nuclei (AGN) resolved in the X-rays. While past results suggested a 150 pc separation dual AGN, three times deeper Chandra imaging, combined with adaptive optics and radio imagi…
Investigating Hα, UV, and IR Star-formation Rate Diagnostics for a Large Sample of z ∼ 2 Galaxies
Shapley, Alice E.; Steidel, Charles C.; Reddy, Naveen A. +1 more
We use a sample of 262 spectroscopically confirmed star-forming galaxies at redshifts 2.08≤slant z≤slant 2.51 to compare Hα, ultraviolet (UV), and IR star formation rate (SFR) diagnostics and to investigate the dust properties of the galaxies. At these redshifts, the Hα line shifts to the {{K}s} band. By comparing {{K}s}-band…
Near-ultraviolet Spectroscopy of Star-forming Galaxies from eBOSS: Signatures of Ubiquitous Galactic-scale Outflows
Schneider, Donald P.; Yèche, Christophe; Newman, Jeffrey +7 more
We present rest-frame near-ultraviolet (NUV) spectroscopy of star-forming galaxies (SFGs) at 0.6 < z < 1.2 from the Extended Baryon Oscillation Spectroscopic Survey (eBOSS) in SDSS-IV. One of the eBOSS programs is to obtain 2″ (about 15 kpc) fiber spectra of about 200,000 emission-line galaxies (ELGs) at redshift z ≳ 0.6. We use the data fro…
Very Large Interstellar Grains as Evidenced by the Mid-infrared Extinction
Wang, Shu; Li, Aigen; Jiang, B. W.
The sizes of interstellar grains are widely distributed, ranging from a few angstroms to a few micrometers. The ultraviolet (UV) and optical extinction constrains the dust in the size range of a couple hundredths of micrometers to several submicrometers. The near and mid infrared (IR) emission constrains the nanometer-sized grains and angstrom-siz…
Weighing Neutrinos with Cosmic Neutral Hydrogen
Viel, Matteo; Bull, Philip; Villaescusa-Navarro, Francisco
We investigate the signatures left by massive neutrinos on the spatial distribution of neutral hydrogen (H i) in the post-reionization era by running hydrodynamic simulations that include massive neutrinos as additional collisionless particles. We find that halos in massive/massless neutrino cosmologies host a similar amount of neutral hydrogen, a…
Three-dimensional Multi-probe Analysis of the Galaxy Cluster A1689
Broadhurst, Tom; Mroczkowski, Tony; Umetsu, Keiichi +7 more
We perform a three-dimensional multi-probe analysis of the rich galaxy cluster A1689, one of the most powerful known lenses on the sky, by combining improved weak-lensing data from new wide-field {{BVR}}Ci\prime z\prime Subaru/Suprime-Cam observations with strong-lensing, X-ray, and Sunyaev-Zel’dovich effect (SZE) data sets. We reconstr…