Search Publications
A Sunyaev-Zel'dovich take on cluster radio haloes - I. Global scaling and bi-modality using Planck data
Basu, Kaustuv
Giant radio haloes in galaxy clusters are the primary evidence for the existence of relativistic particles (cosmic rays) and magnetic fields over Mpc scales. Observational tests for the different theoretical models explaining their powering mechanism have so far been obtained through X-ray selection of clusters, e.g. by comparing cluster X-ray lum…
Isotopic Ratios in Titan's Methane: Measurements and Modeling
Irwin, P. G. J.; Teanby, N. A.; Flasar, F. M. +10 more
The existence of methane in Titan's atmosphere (~6% level at the surface) presents a unique enigma, as photochemical models predict that the current inventory will be entirely depleted by photochemistry in a timescale of ~20 Myr. In this paper, we examine the clues available from isotopic ratios (12C/13C and D/H) in Titan's m…
The Spectrum of the Recycled PSR J0437-4715 and Its White Dwarf Companion
Pavlov, George G.; Kargaltsev, Oleg; Kaplan, David L. +4 more
We present extensive spectral and photometric observations of the recycled pulsar/white dwarf binary containing PSR J0437-4715, which we analyzed together with archival X-ray and gamma-ray data, to obtain the complete mid-infrared to gamma-ray spectrum. We first fit each part of the spectrum separately, and then the whole multi-wavelength spectrum…
The Magnetic Energy-Helicity Diagram of Solar Active Regions
Georgoulis, Manolis K.; Tziotziou, Kostas; Raouafi, Nour-Eddine
Using a recently proposed nonlinear force-free method designed for single-vector magnetograms of solar active regions, we calculate the instantaneous free magnetic energy and relative magnetic helicity budgets in 162 vector magnetograms corresponding to 42 different active regions. We find a statistically robust, monotonic correlation between the …
Rapid disappearance of a warm, dusty circumstellar disk
Zuckerman, B.; Murphy, Simon J.; Song, Inseok +3 more
Stars form with gaseous and dusty circumstellar envelopes, which rapidly settle into disks that eventually give rise to planetary systems. Understanding the process by which these disks evolve is paramount in developing an accurate theory of planet formation that can account for the variety of planetary systems discovered so far. The formation of …
Time-resolved Ultraviolet Spectroscopy of the M-dwarf GJ 876 Exoplanetary System
Roberge, Aki; France, Kevin; Linsky, Jeffrey L. +2 more
Extrasolar planets orbiting M-stars may represent our best chance to discover habitable worlds in the coming decade. The ultraviolet spectrum incident upon both Earth-like and Jovian planets is critically important for proper modeling of their atmospheric heating and chemistry. In order to provide more realistic inputs for atmospheric models of pl…
Strong lensing by a node of the cosmic web. The core of MACS J0717.5+3745 at z = 0.55
Smail, I.; Kneib, J. -P.; Smith, G. P. +9 more
We present results of a strong-lensing analysis of MACS J0717.5+3745 (hereafter MACS J0717), an extremely X-ray luminous galaxy cluster at z = 0.55. Observations at different wavelengths reveal a complex and dynamically very active cluster, whose core is connected to a large scale filament extended over several Mpc. Using multi-passband imaging da…
Gas Emissions in Planck Cold Dust Clumps—A Survey of the J = 1-0 Transitions of 12CO, 13CO, and C18O
Li, Di; Liu, Tie; Qin, Sheng-Li +3 more
A survey toward 674 Planck cold clumps of the Early Cold Core Catalogue (ECC) in the J = 1-0 transitions of 12CO, 13CO, and C18O has been carried out using the Purple Mountain Observatory 13.7 m telescope. Six hundred seventy-three clumps were detected with 12CO and 13CO emission, and 68% of t…
Stochastic gravito-inertial modes discovered by CoRoT in the hot Be star HD 51452
Poretti, E.; Rainer, M.; Samadi, R. +24 more
Context. Be stars are rapidly rotating stars with a circumstellar decretion disk. They usually undergo pressure and/or gravity pulsation modes excited by the κ-mechanism, i.e. an effect of the opacity of iron-peak elements in the envelope of the star. In the Milky Way, p-modes are observed in stars that are hotter than or equal to the B3 spectral …
The INTEGRAL/IBIS AGN catalogue - I. X-ray absorption properties versus optical classification
Masetti, N.; Bird, A. J.; Ubertini, P. +5 more
In this work we present the most comprehensive INTEGRAL active galactic nucleus (AGN) sample. It lists 272 AGN for which we have secure optical identifications, precise optical spectroscopy and measured redshift values plus X-ray spectral information, i.e. 2-10 and 20-100 keV fluxes plus column density. Here we mainly use this sample to study the …