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The signal of decaying dark matter with hydrodynamical simulations
Lovell, Mark R.; Crain, Robert A.; Schaye, Joop +11 more
Dark matter particles may decay, emitting photons. Drawing on the EAGLE family of hydrodynamical simulations of galaxy formation - including the APOSTLE and C-EAGLE simulations - we assess the systematic uncertainties and scatter on the decay flux from different galaxy classes, from Milky Way satellites to galaxy clusters, and compare our results …
Peering at the outflow mechanisms in the transitional pulsar PSR J1023+0038: simultaneous VLT, XMM-Newton, and Swift high-time resolution observations
D'Avanzo, P.; Campana, S.; Casella, P. +6 more
We report on a simultaneous near-infrared, optical, and X-ray campaign performed in 2017 with the XMM-Newton and Swift satellites and the HAWK-I instrument mounted on the Very Large Telescope (VLT) on the transitional millisecond pulsar PSR J1023+0038. Near-infrared observations were performed in fast-photometric mode (0.5 s exposure time) in orde…
Broad-band X-ray analysis of local mid-infrared-selected Compton-thick AGN candidates
Pozzi, F.; Vignali, C.; Gruppioni, C. +2 more
The estimate of the number and space density of obscured active galactic nuclei (AGNs) over cosmic time still represents an open issue. While the obscured AGN population is a key ingredient of the X-ray background synthesis models and is needed to reproduce its shape, a complete census of obscured AGN is still missing. Here we test the selection o…
The Dynamics of Saturn's Main Aurorae
Badman, S. V.; Ray, L. C.; Cowley, S. W. H. +9 more
Saturn's main aurorae are thought to be generated by plasma flow shears associated with a gradient in angular plasma velocity in the outer magnetosphere. Dungey cycle convection across the polar cap, in combination with rotational flow, may maximize (minimize) this flow shear at dawn (dusk) under strong solar wind driving. Using imagery from Cassi…
Unusually high magnetic fields in the coma of 67P/Churyumov-Gerasimenko during its high-activity phase
Tsurutani, B. T.; Behar, E.; Nilsson, H. +10 more
Aims: On July 3, 2015, an unprecedented increase in the magnetic field magnitude was measured by the Rosetta spacecraft orbiting comet 67P/Churyumov-Gerasimenko (67P). This increase was accompanied by large variations in magnetic field and ion and electron density and energy. To our knowledge, this unusual event marks the highest magnetic fie…
Flow pattern of accelerated cometary ions inside and outside the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko
Behar, E.; Nilsson, H.; Goetz, C. +3 more
Analyzing data from the Ion Composition Analyzer on board the Rosetta spacecraft, we studied a flow pattern of accelerated cometary ions (40-80 eV) inside and outside the diamagnetic cavity of comet 67P/Churyumov-Gerasimenko (67P). We found that the accelerated ions are intermittently observed and are ten times more frequently observed outside the…
Twin CME Launched by a Blowout Jet Originated from the Eruption of a Quiet-Sun Mini-filament
Srivastava, A. K.; Dwivedi, B. N.; Rao, Y. K. +1 more
We study a quiet-Sun blowout jet which was observed on 2014 May 16 by the instruments on board the Solar Dynamics Observatory (SDO). We find the twin CME as jet-like and bubble-like CMEs simultaneously as observed by LASCO C2 on board the Solar and Heliospheric Observatory (SoHO), and the Solar Terrestrial Relation Observatory (STEREO_A and STEREO…
A SINFONI view of the nuclear activity and circumnuclear star formation in NGC 4303 - II. Spatially resolved stellar populations
Colina, L.; Burtscher, L.; Pastoriza, M. G. +11 more
We present a spatially resolved stellar population study of the inner ∼200 pc radius of NGC 4303 based on near-infrared integral field spectroscopy with SINFONI/VLT at a spatial resolution of 40-80 pc and using the STARLIGHT code. We found that the distribution of the stellar populations presents a spatial variation, suggesting an age stratificati…
Nonequilibrium Ionization Effects on Solar EUV and X-Ray Imaging Observations
Moon, Yong-Jae; Reeves, Katharine K.; Raymond, John C. +3 more
During transient events such as major solar eruptions, the plasma can be far from the equilibrium ionization state because of rapid heating or cooling. Nonequilibrium ionization (NEI) is important in rapidly evolving systems where the thermodynamical timescale is shorter than the ionization or recombination timescales. We investigate the effects o…
Luminosity Ratio between [O IV] 25.89 µm Line and Nuclear Continuum 12 µm as a Diagnostic for “Buried” AGNs
Imanishi, Masatoshi; Tanimoto, Atsushi; Ueda, Yoshihiro +3 more
We propose new diagnostics that utilize the [O IV] 25.89 µm and nuclear (subarcsecond scale) 12 µm luminosity ratios for identifying whether an active galactic nucleus (AGN) is deeply “buried” in their surrounding materials. Utilizing a sample of 16 absorbed AGNs at redshifts lower than 0.03 in the Swift/BAT catalog observed with Suzak…