Search Publications

Energy dependence of SEP electron and proton onset times

St. Cyr, O. C.; Gopalswamy, N.; Mäkelä, P. +1 more

We study the large solar energetic particle (SEP) events that were detected by GOES in the >10 MeV energy channel during December 2006 to March 2014. We derive and compare solar particle release (SPR) times for the 0.25-10.4 MeV electrons and 10-100 MeV protons for the 28 SEP events. In the study, the electron SPR times are derived with the tim…

Soft X-Ray Excess from Shocked Accreting Plasma in Active Galactic Nuclei

Tombesi, Francesco; Takahashi, Masaaki; Clark, Peter +2 more

We propose a novel theoretical model to describe the physical identity of the soft X-ray excess that is ubiquitously detected in many Seyfert galaxies, by considering a steady-state, axisymmetric plasma accretion within the innermost stable circular orbit around a black hole (BH) accretion disk. We extend our earlier theoretical investigations on …

Injection of solar energetic particles into both loop legs of a magnetic cloud

Temmer, M.; Veronig, A.; Gómez-Herrero, R. +4 more

Context. Each of the two Solar TErrestrial RElations Observatory (STEREO) spacecraft carries a Solar Electron and Proton Telescope (SEPT) which measures electrons and protons. Anisotropy observations are provided in four viewing directions: along the nominal magnetic field Parker spiral in the ecliptic towards the Sun (SUN) and away from the Sun (…

Rating global magnetosphere model simulations through statistical data-model comparisons

Ridley, A. J.; De Zeeuw, D. L.; Rastätter, L.

The Community Coordinated Modeling Center (CCMC) was created in 2000 to allow researchers to remotely run simulations and explore the results through online tools. Since that time, over 10,000 simulations have been conducted at CCMC through their runs-on-request service. Many of those simulations have been event studies using global magnetohydrody…

Planetary period oscillations in Saturn's magnetosphere: Further comments on the relationship between post-equinox properties deduced from magnetic field and Saturn kilometric radiation measurements

Cowley, S. W. H.; Provan, G.

We discuss the planetary period oscillations (PPOs) observed by the Cassini spacecraft in Saturn's magnetosphere, in particular the relationship between the properties of the PPOs in the post-equinox interval as observed in magnetic field data by Andrews et al. (2012) and Provan et al. (2013, 2014) and in Saturn kilometric radiation (SKR) emission…

Constraints on the formation and properties of a Martian lobate debris apron: Insights from high-resolution topography, SHARAD radar data, and a numerical ice flow model

Parsons, Reid; Holt, John

Lobate debris aprons (LDAs) are midlatitude deposits of debris-covered ice formed during one or more periods of glaciation during the Amazonian period. However, little is known about the climate conditions that led to LDA formation. We explore a hypothesis in which a single, extended period of precipitation of ice on the steep slopes of Euripus Mo…

Probing dark energy via galaxy cluster outskirts

Sun, Ming; Morandi, Andrea

We present a Bayesian approach to combine Planck data and the X-ray physical properties of the intracluster medium in the virialization region of a sample of 320 galaxy clusters (0.056 < z < 1.24, kT ≳ 3 keV) observed with Chandra. We exploited the high level of similarity of the emission measure in the cluster outskirts as cosmology proxy. …

Evidence for a Magnetic Flux Rope in Observations of a Solar Prominence-Cavity System

Reeves, Katharine K.; Su, Yingna; Jibben, Patricia R.

Testing distance duality with CMB anisotropies

Räsänen, Syksy; Väliviita, Jussi; Kosonen, Ville

We constrain deviations of the form T propto (1+z)^1+epsilon from the standard redshift-temperature relation, corresponding to modifying distance duality as D_L = (1+z)^2(1+epsilon) D_A. We consider a consistent model, in which both the background and perturbation equations are changed. For this purpose, we …

A deep Chandra observation of the interacting star-forming galaxy Arp 299

Zezas, A.; Ballo, L.; Della Ceca, R. +1 more

We present results from a 90 ks Chandra ACIS-S observation of the X-ray luminous interacting galaxy system Arp 299 (NGC 3690/IC 694). We detect 25 discrete X-ray sources with luminosities above ∼4.0 × 10³⁸ erg s^-1 covering the entire Ultra Luminous X-ray source (ULX) regime. Based on the hard X-ray spectra of the non-nuclear …