Search Publications
The thermal and non-thermal components within and between galaxy clusters Abell 399 and Abell 401
Sarazin, Craig L.; Hilton, Matt; Sifón, Cristóbal +28 more
We measure the local correlation between radio emission and Compton-y signal across two galaxy clusters, Abell 399 and Abell 401, using maps from the Low Frequency Array and the Atacama Cosmology Telescope + Planck. These data sets allow us to make the first measurement of this kind at ~arcmin resolution. We find that the radio brightness scales a…
Evaluating Non-LTE Spectral Inversions with ALMA and IBIS
Reardon, Kevin P.; Uitenbroek, Han; Hofmann, Ryan A. +3 more
We present observations of a solar magnetic network region in the millimeter continuum with the Atacama Large Millimeter/submillimeter Array (ALMA) and in the Ca 8542 and Na 5896 Å spectral lines with the Interferometric Bidimensional Spectrometer (IBIS). Our goal is to compare the measurement of local gas temperatures provided by ALMA with the te…
The morphology of the ejecta of SN 1987A at 31 yr from 1150 to 10 000 Å
Larsson, J.; Sollerman, J.; Lundqvist, P. +7 more
We present spectroscopy of the ejecta of SN 1987A in 2017 and 2018 from the Hubble Space Telescope and the Very Large Telescope, covering the wavelength range between 1150 and $10\, 000$ Å. At 31 yr, this is the first epoch with coverage over the ultraviolet-to-near-infrared range since 1995. We create velocity maps of the ejecta in the H α, Mg II…
The Hot Neptune WASP-166 b with ESPRESSO - I. Refining the planetary architecture and stellar variability
Lafarga, M.; Lendl, M.; Lovis, C. +24 more
In this paper, we present high-resolution spectroscopic transit observations from ESPRESSO of the super-Neptune WASP-166 b. In addition to spectroscopic ESPRESSO data, we analyse photometric data from TESS of six WASP-166 b transits along with simultaneous NGTS observations of the ESPRESSO runs. These observations were used to fit for the planetar…
Charge Exchange X-Ray Emission Detected in Multiple Shells of Supernova Remnant G296.1-0.5
Uchida, Hiroyuki; Fukui, Yasuo; Tanaka, Takaaki +5 more
Recent high-resolution X-ray spectroscopy revealed the possible presence of charge exchange (CX) X-ray emission in supernova remnants (SNRs). Although CX is expected to take place at the outermost edges of SNR shells, no significant measurement has been reported so far due to the lack of nearby SNR samples. Here we present an X-ray study of SNR G2…
Toward an X-ray inventory of nearby neutron stars
Santangelo, A.; Pavlov, G. G.; Posselt, B. +1 more
Context. The X-ray emission of neutron stars enables a probe of their temperatures, geometries and magnetospheric properties. The current number of X-ray emitting pulsars is insufficient to rule out observational biases that may arise from poorly known distance, age, or location of the neutron stars. One approach to overcome such biases is to crea…
Diagnostics of Non-Maxwellian Electron Distributions in Solar Active Regions from Fe XII Lines Observed by the Hinode Extreme Ultraviolet Imaging Spectrometer and Interface Region Imaging Spectrograph
Mason, H. E.; Del Zanna, G.; Testa, P. +3 more
We present joint Hinode Extreme Ultraviolet Imaging Spectrometer (EIS) and Interface Region Imaging Spectrograph (IRIS) observations of Fe XII lines in active regions, both on-disk and off-limb. We use an improved calibration for the EIS data, and find that the 192.4 Å/1349 Å observed ratio is consistent with the values predicted by CHIANTI and th…
AWSoM Magnetohydrodynamic Simulation of a Solar Active Region with Realistic Spectral Synthesis
Landi, Enrico; van der Holst, Bart; Szente, Judit +6 more
For the first time, we simulate the detailed spectral line emission from a solar active region (AR) with the Alfvén Wave Solar Model (AWSoM). We select an AR appearing near disk center on 2018 July 13 and use the National Solar Observatory's Helioseismic and Magnetic Imager synoptic magnetogram to specify the magnetic field at the model's inner bo…
The Chemical Composition of Extreme-velocity Stars
Hawkins, Keith; Frebel, Anna; Ji, Alexander P. +5 more
Little is known about the origin of the fastest stars in the Galaxy. Our understanding of the chemical evolution history of the Milky Way and surrounding dwarf galaxies allows us to use the chemical composition of a star to investigate its origin and to say whether it was formed in situ or was accreted. However, the fastest stars, the hypervelocit…
Blazars at Very High Energies: Emission Modelling
Zech, Andreas; Sol, Hélène
Blazars are very broadband cosmic sources with spectra spanning over twenty orders of magnitude in frequency, down to the 100 MHz regime in the radio range, up to VHE at several tens of TeV. The modelling of their spectral energy distribution at high energies currently considers two main classes of models, leptonic and lepto-hadronic, which both s…