Search Publications
Molecular depletion times and the CO-to-H2 conversion factor in metal-poor galaxies
Maiolino, R.; Menten, K. M.; Hunt, L. K. +8 more
Tracing molecular hydrogen content with carbon monoxide in low-metallicity galaxies has been exceedingly difficult. Here we present a new effort, with IRAM 30-m observations of 12CO(1-0) of a sample of 8 dwarf galaxies having oxygen abundances ranging from 12 + log(O/H) ~ 7.7 to 8.4. CO emission is detected in all galaxies, including th…
Circumsolar Energetic Particle Distribution on 2011 November 3
Lario, D.; Rodríguez-Pacheco, J.; Gómez-Herrero, R. +7 more
Late on 2011 November 3, STEREO-A, STEREO-B, MESSENGER, and near-Earth spacecraft observed an energetic particle flux enhancement. Based on the analysis of in situ plasma and particle observations, their correlation with remote sensing observations, and an interplanetary transport model, we conclude that the particle increases observed at multiple…
Resonant Absorption of Transverse Oscillations and Associated Heating in a Solar Prominence. I. Observational Aspects
Van Doorsselaere, Tom; Antolin, Patrick; De Pontieu, Bart +3 more
Transverse magnetohydrodynamic waves have been shown to be ubiquitous in the solar atmosphere and can, in principle, carry sufficient energy to generate and maintain the Sun’s million-degree outer atmosphere or corona. However, direct evidence of the dissipation process of these waves and subsequent heating has not yet been directly observed. Here…
The XMM Cluster Survey: testing chameleon gravity using the profiles of clusters
Hilton, Matt; Zhao, Gong-Bo; Stott, John P. +17 more
The chameleon gravity model postulates the existence of a scalar field that couples with matter to mediate a fifth force. If it exists, this fifth force would influence the hot X-ray emitting gas filling the potential wells of galaxy clusters. However, it would not influence the clusters weak lensing signal. Therefore, by comparing X-ray and weak …
OGLE-III Microlensing Events and the Structure of the Galactic Bulge
Udalski, Andrzej; Szymański, Michał K.; Skowron, Jan +9 more
We present and study the largest and most comprehensive catalog of microlensing events ever constructed. The sample of standard microlensing events comprises 3718 unique events from 2001-2009 with 1409 events that had not been detected before in real-time by the Early Warning System of the Optical Gravitational Lensing Experiment. The search pipel…
The 2014 March 29 X-flare: Subarcsecond Resolution Observations of Fe XXI λ1354.1
Jaeggli, Sarah; Tian, Hui; Young, Peter R.
The Interface Region Imaging Spectrometer (IRIS) is the first solar instrument to observe ~10 MK plasma at subarcsecond spatial resolution through imaging spectroscopy of the Fe XXI λ1354.1 forbidden line. IRIS observations of the X1 class flare that occurred on 2014 March 29 at 17:48 UT reveal Fe XXI emission from both the flare ribbons and the p…
X-ray coherent pulsations during a sub-luminous accretion disc state of the transitional millisecond pulsar XSS J12270-4859.
de Martino, D.; Torres, D. F.; Pellizzoni, A. +4 more
We present the first detection of X-ray coherent pulsations from the transitional millisecond pulsar XSS J12270-4859, while it was in a sub-luminous accretion disc state characterized by a 0.5-10 keV luminosity of 5 × 1033 erg s-1 (assuming a distance of 1.4 kpc). Pulsations were observed by XMM-Newton at an rms amplitude of …
Quintessential inflation with canonical and noncanonical scalar fields and Planck 2015 results
Geng, Chao-Qiang; Saridakis, Emmanuel N.; Myrzakulov, R. +2 more
We investigate two classes of models of quintessential inflation, based upon canonical as well as noncanonical scalar fields. In particular, introducing potentials steeper than the standard exponential, we construct models that can give rise to a successful inflationary phase, with signatures consistent with Planck 2015 results. Additionally, usin…
The Complex Accretion Geometry of GX 339-4 as Seen by NuSTAR and Swift
Harrison, F. A.; Stern, D.; Zhang, W. W. +19 more
We present spectral analyses of five Nuclear Spectroscopic Telescope Array and Swift observations of GX 339-4 taken during a failed outburst during the summer of 2013. These observations cover Eddington luminosity fractions in the range ≈0.9%-6%. Throughout this outburst GX 339-4 stayed in the hard state and all five observations show similar X-ra…
The Martian atmospheric ion escape rate dependence on solar wind and solar EUV conditions: 1. Seven years of Mars Express observations
Barabash, Stas; Nilsson, Hans; Holmström, Mats +3 more
More than 7 years of ion flux measurements in the energy range 10 eV-15 keV have allowed the ASPERA-3/IMA (Analyzer of Space Plasmas and Energetic Ions/Ion Mass Analyzer) instrument on Mars Express to collect a large database of ion measurements in the Mars environment, over a wide range of upstream solar wind (density and velocity) and radiation …