Search Publications
Infrared and X-Ray Evidence of an AGN in the NGC 3256 Southern Nucleus
Ohyama, Youichi; Terashima, Yuichi; Sakamoto, Kazushi
We investigate signs of an active galactic nucleus (AGN) in the luminous infrared (IR) galaxy NGC 3256 at both IR and X-ray wavelengths. NGC 3256 has double nuclei: the northern and southern (hereafter, N and S nuclei, respectively). We show that the Spitzer IRAC colors extracted at the S nucleus are AGN-like, and the Spitzer IRS spectrum is bluer…
The CO2 continuum absorption in the 1.10- and 1.18-µm windows on Venus from Maxwell Montes transits by SPICAV IR onboard Venus express
Bertaux, Jean-Loup; Korablev, Oleg; Bézard, Bruno +2 more
One of the difficulties in modeling Venus' nightside atmospheric windows is the need to apply CO2 continuum opacity due to collision-induced CO2 bands and/or extreme far wings of strong allowed CO2 bands. Characterizing the CO2 continuum absorption at near-IR wavelengths as well as searching for a possib…
New Extinction and Mass Estimates from Optical Photometry of the Very Low Mass Brown Dwarf Companion CT Chamaeleontis B with the Magellan AO System
Barman, Travis S.; Close, Laird M.; Males, Jared R. +9 more
We used the Magellan adaptive optics system and its VisAO CCD camera to image the young low mass brown dwarf companion CT Chamaeleontis B for the first time at visible wavelengths. We detect it at r', i', z', and YS . With our new photometry and T eff ~ 2500 K derived from the shape of its K-band spectrum, we find that CT Cha…
A Multi-wavelength Mass Analysis of RCS2 J232727.6-020437, A ∼3 × 1015 M⊙ Galaxy Cluster at z = 0.7
Sharon, K.; Gladders, M. D.; Schrabback, T. +20 more
We present an initial study of the mass and evolutionary state of a massive and distant cluster, RCS2 J232727.6-020437. This cluster, at z = 0.6986, is the richest cluster discovered in the RCS2 project. The mass measurements presented in this paper are derived from all possible mass proxies: X-ray measurements, weak-lensing shear, strong lensing,…
Simultaneous Estimation of Photometric Redshifts and SED Parameters: Improved Techniques and a Realistic Error Budget
Gawiser, Eric; Acquaviva, Viviana; Raichoor, Anand
We seek to improve the accuracy of joint galaxy photometric redshift estimation and spectral energy distribution (SED) fitting. By simulating different sources of uncorrected systematic errors, we demonstrate that if the uncertainties in the photometric redshifts are estimated correctly, so are those on the other SED fitting parameters, such as st…
Structure and Dynamics of the 2012 November 13/14 Eclipse White-light Corona
Seaton, D. B.; Rušin, V.; Saniga, M. +9 more
Continuing our series of observations of coronal motion and dynamics over the solar-activity cycle, we observed from sites in Queensland, Australia, during the 2012 November 13 (UT)/14 (local time) total solar eclipse. The corona took the low-ellipticity shape typical of solar maximum (flattening index ɛ = 0.01), a change from the composite corona…
5.9-keV Mn K-shell X-ray luminosity from the decay of 55Fe in Type Ia supernova models
Wilms, J.; Diehl, R.; Sim, S. A. +12 more
We show that the X-ray line flux of the Mn Kα line at 5.9 keV from the decay of 55Fe is a promising diagnostic to distinguish between Type Ia supernova (SN Ia) explosion models. Using radiation transport calculations, we compute the line flux for two three-dimensional explosion models: a near-Chandrasekhar mass delayed detonation and a …
Swift discoveries of new populations of extremely long duration high energy transient
Levan, A. J.
Recent observations with Swift have begun to uncover γ-ray transients whose total energies are comparable to those of gamma-ray bursts (GRB), but have a duration an order of magnitude or more longer than the bulk of the GRB population. Some are suggested to form a new population of ultra-long GRBs, with a mean duration around 104 s, whi…
Holographic dark energy with cosmological constant
Li, Nan; Li, Miao; Hu, Yazhou +1 more
Inspired by the multiverse scenario, we study a heterotic dark energy model in which there are two parts, the first being the cosmological constant and the second being the holographic dark energy, thus this model is named the ΛHDE model. By studying the ΛHDE model theoretically, we find that the parameters d and Ωhde are divided into a…
Constraints from Comets on the Formation and Volatile Acquisition of the Planets and Satellites
Hartogh, P.; Mousis, O.; Marty, B. +4 more
Comets play a dual role in understanding the formation and evolution of the solar system. First, the composition of comets provides information about the origin of the giant planets and their moons because comets formed early and their composition is not expected to have evolved significantly since formation. They, therefore serve as a record of c…