Search Publications
The First Ultraviolet Detection of the Large Magellanic Cloud Pulsar PSR B0540-69 and Its Multi-wavelength Properties
de Luca, A.; Barbieri, C.; Naletto, G. +9 more
We observed the young (∼1700 yr) pulsar PSR B0540-69 in the ultraviolet for the first time with the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope. Imaging observations with the NUV-MAMA and ultraviolet FUV-MAMA detectors in TIME-TAG mode allowed us to clearly detect the pulsar in two bands around 2350 and 1590 Å, with ma…
LOFAR Discovery of a Radio Halo in the High-redshift Galaxy Cluster PSZ2 G099.86+58.45
Di Gennaro, G.; Brunetti, G.; Shimwell, T. W. +15 more
In this Letter, we report the discovery of a radio halo in the high-redshift galaxy cluster PSZ2 G099.86+58.45 (z = 0.616) with the LOw Frequency ARray (LOFAR) at 120-168 MHz. This is one of the most distant radio halos discovered so far. The diffuse emission extends over ∼1 Mpc and has a morphology similar to that of the X-ray emission as reveale…
Spatially Resolved Outflows in a Seyfert Galaxy at z = 2.39
Dahle, H.; Rigby, J. R.; Sharon, K. +11 more
We present the first spatially resolved analysis of rest-frame optical and UV imaging and spectroscopy for a lensed galaxy at z = 2.39 hosting a Seyfert active galactic nucleus (AGN). Proximity to a natural guide star has enabled observations with high signal-to-noise ratio using Very Large Telescope SINFONI + adaptive optics (AO) of rest-frame op…
Uncertainty Quantification in Sunspot Counts
Mathieu, Sophie; von Sachs, Rainer; Ritter, Christian +2 more
Observing and counting sunspots constitutes one of the longest-running scientific experiments, with first observations dating back to Galileo (around 1610). Today the sunspot number (SN) time series acts as a benchmark of solar activity in a large range of physical models. An appropriate statistical modeling, adapted to the time series’ complex na…
Nitrogen-containing Anions and Tholin Growth in Titan’s Ionosphere: Implications for Cassini CAPS-ELS Observations
Coates, Andrew J.; Carrasco, Nathalie; Desai, Ravindra T. +4 more
The Cassini Plasma Spectrometer (CAPS) Electron Spectrometer (ELS) instrument on board Cassini revealed an unexpected abundance of negative ions above 950 km in Titan’s ionosphere. In situ measurements indicated the presence of negatively charged particles with mass-over-charge ratios up to 13,800 u/q. At present, only a handful of anions have bee…
Is Supernova Remnant Cassiopeia A a PeVatron?
Zhang, Xiao; Liu, Siming
Cassiopeia A, a well-observed young core-collapse supernova remnant (SNR), is considered to be one of the best candidates for studying very high-energy particle acceleration up to PeV via the diffusive shock mechanism. Recently, MAGIC observations revealed a γ-ray spectral cutoff at ∼ 3.5 {TeV}, suggesting that if the TeV γ-rays have a hadronic or…
Chandra-HETGS Characterization of an Outflowing Wind in the Accreting Millisecond Pulsar IGR J17591-2342
Wilms, Jörn; Chenevez, Jérôme; Rodriguez, Jérôme +5 more
An accreting millisecond X-ray pulsar, IGR J17591-2342 was discovered in 2018 August in scans of the Galactic bulge and center by the International Gamma-Ray Astrophysics Laboratory X-ray and gamma-ray observatory. It exhibited an unusual outburst profile with multiple peaks in the X-ray, as observed by several X-ray satellites over 3 months. Here…
The Influence of Polar Coronal Holes on the Polar ENA Flux Observed by IBEX
Reisenfeld, D. B.; McComas, D. J.; Schwadron, N. A. +6 more
Polar coronal holes (PCHs) fill the high-latitude heliosphere with fast solar wind during the minimum phase of the solar cycle. This leads to a hardening of the energy spectrum of the proton plasma in the inner heliosheath (IHS), observed as energetic neutral atoms (ENAs) by the Interstellar Boundary Explorer (IBEX). In particular, the highest-ene…
Simulating Solar Coronal Mass Ejections Constrained by Observations of Their Speed and Poloidal Flux
Singh, T.; Yalim, M. S.; Pogorelov, N. V. +1 more
We demonstrate how the parameters of a Gibson-Low flux-rope-based coronal mass ejection (CME) can be constrained using remote observations. Our Multi-Scale Fluid-Kinetic Simulation Suite has been used to simulate the propagation of a CME in a data-driven solar corona background computed using the photospheric magnetogram data. We constrain the CME…
X-Ray and Gamma-Ray Emission from Core-collapse Supernovae: Comparison of Three-dimensional Neutrino-driven Explosions with SN 1987A
Fransson, Claes; Janka, Hans-Thomas; Alp, Dennis +7 more
During the first few hundred days after the explosion, core-collapse supernovae (SNe) emit down-scattered X-rays and gamma-rays originating from radioactive line emissions, primarily from the 56Ni → 56Co → 56Fe chain. We use supernova (SN) models based on three-dimensional neutrino-driven explosion simulations of s…