Search Publications
Radiative seesaw model with degenerate Majorana dark matter
Okada, Hiroshi; Nomura, Takaaki; Orikasa, Yuta
We study a three-loop-induced neutrino mass model with exotic vectorlike isospin doublet leptons which contain a dark matter candidate. Then we explore lepton flavor violations and dark matter physics in a coannihilation system. In this paper, the nearly degenerate Majorana fermion dark matter can naturally be achieved at the two-loop level, while…
Treatment of non-sparse cratering in planetary surface dating
Michael, G. G.; Kneissl, T.; Schmedemann, N.
We here propose a new technique to derive crater size-frequency distributions (CSFDs) from non-sparsely cratered surfaces, by accounting for the loss of craters due to subsequent crater/ejecta coverage. This approach, which we refer to as the buffered non-sparseness correction (BNSC), relates each crater to a measurement area found by excluding re…
Spatially Resolved Spectroscopy of a Balmer-dominated Shock in the Cygnus Loop: An Extremely Thin Cosmic-Ray Precursor?
Katsuda, Satoru; Lee, Jae-Joon; Raymond, John C. +9 more
We present high-resolution long-slit spectroscopy of a Balmer-dominated shock in the northeastern limb of the Cygnus Loop with the Subaru high dispersion spectrograph. By setting the slit angle along the shock normal, we investigate variations of the flux and profile of the Hα line from preshock to postshock regions with a spatial resolution of ∼4…
One year in the Earth's magnetosphere: A global MHD simulation and spacecraft measurements
Kallio, E.; Palin, L.; Facskó, G. +6 more
The response of the Earth's magnetosphere to changing solar wind conditions is studied with a 3-D Magnetohydrodynamic (MHD) model. One full year (155 Cluster orbits) of the Earth's magnetosphere is simulated using Grand Unified Magnetosphere Ionosphere Coupling simulation (GUMICS-4) magnetohydrodynamic code. Real solar wind measurements are given …
Enhanced erosion rates on Mars during Amazonian glaciation
Head, James W.; Fassett, Caleb I.; Levy, Joseph S.
Observations of Mars from the surface and from orbit suggest that erosion rates over the last ∼3 Gyr (the Amazonian) have been as slow as 10-5 m/Myr and have been dominated by aeolian processes, while ancient (Noachian) erosion rates may have been orders of magnitude higher due to impact bombardment and fluvial activity. Amazonian-aged …
Sub-kpc star formation law in the local luminous infrared galaxy IC 4687 as seen by ALMA
Colina, L.; Villar-Martín, M.; Planesas, P. +8 more
We analyze the spatially resolved (250 pc scales) and integrated star formation (SF) law in the local luminous infrared galaxy (LIRG) IC 4687. This is one of the first studies of the SF law on a starburst LIRG at these small spatial scales. We combined new interferometric ALMA CO(2-1) data with existing HST/NICMOS Paα narrowband imaging and VLT/SI…
A Study of the Elements Copper through Uranium in Sirius A: Contributions from STIS and Ground-Based Spectra
Wahlgren, G. M.; Castelli, F.; Monier, R. +3 more
We determine abundances or upper limits for all of the 55 stable elements from copper to uranium for the A1 Vm star Sirius. The purpose of the study is to assemble the most complete picture of elemental abundances with the hope of revealing the chemical history of the brightest star in the sky, apart from the Sun. We also explore the relationship …
Swift J174540.7-290015: a new accreting binary in the Galactic Centre
Haberl, F.; Ponti, G.; Rea, N. +8 more
We report on the identification of the new Galactic Centre (GC) transient Swift J174540.7-290015 as a likely low-mass X-ray binary located at only 16 arcsec from Sgr A⋆. This transient was detected on 2016 February 6, during the Swift GC monitoring, and it showed long-term spectral variations compatible with a hard- to soft-state transi…
A Deep Chandra ACIS Survey of M51
Kuntz, K. D.; Long, Knox S.; Kilgard, Roy E.
We have obtained a deep X-ray image of the nearby galaxy M51 using Chandra. Here we present the catalog of X-ray sources detected in these observations and provide an overview of the properties of the point-source population. We find 298 sources within the D 25 radii of NGC 5194/5, of which 20% are variable, a dozen are classical transi…
Narrowband Gyrosynchrotron Bursts: Probing Electron Acceleration in Solar Flares
Kontar, Eduard P.; Fleishman, Gregory D.; Nita, Gelu M. +1 more
Recently, in a few case studies we demonstrated that gyrosynchrotron microwave emission can be detected directly from the acceleration region when the trapped electron component is insignificant. For the statistical study reported here, we have identified events with steep (narrowband) microwave spectra that do not show a significant trapped compo…