Search Publications
Testing gravity at large scales with H I intensity mapping
Pourtsidou, Alkistis
We investigate the possibility of testing Einstein's general theory of relativity (GR) and the standard cosmological model via the EG statistic using neutral hydrogen (H I) intensity mapping. We generalize the Fourier space estimator for EG to include H I as a biased tracer of matter and forecast statistical errors using H I …
Richness-based masses of rich and famous galaxy clusters
Andreon, S.
We present a catalog of galaxy cluster masses derived by exploiting the tight correlation between mass and richness, I.e., a properly computed number of bright cluster galaxies. The richness definition adopted in this work is properly calibrated, shows a small scatter with mass, and has a known evolution, which means that we can estimate accurate …
Modified ion-Weibel instability as a possible source of wave activity at Comet 67P/Churyumov-Gerasimenko
Motschmann, Uwe; Glassmeier, Karl-Heinz; Meier, Patrick
We analytically discuss wave excitation in a homogeneous three component plasma consisting of solar wind protons, electrons and a beam of cometary water ions applied to the plasma environment of comet 67P/Churyumov-Gerasimenko. The resulting dispersion relations are studied in a solar wind rest frame, where a cometary current is solely generated b…
Giant lobes of Centaurus A as seen in radio and γ-ray images obtained with the Fermi-LAT and Planck satellites
Aharonian, Felix; Yang, Rui-zhi; Sun, Xiao-na +1 more
The γ-ray data of Fermi-LAT on the giant lobes of Centaurus A are analysed together with the high frequency radio data obtained with the Planck satellite. The large γ-ray photon statistics, accumulated during seven years of observations, and the recently updated Fermi-LAT collaboration software tools allow substantial extension of the detected γ-r…
A high mass progenitor for the Type Ic Supernova 2007gr inferred from its environment
Ramirez-Ruiz, Enrico; Maund, Justyn R.
We present an analysis of late-time Hubble Space Telescope Wide Field Camera 3 (WFC3) and Wide Field Planetary Camera 2 (WFPC2) observations of the site of the Type Ic supernova (SN) 2007gr in NGC 1058. The SN is barely recovered in the late-time WFPC2 observations, while a possible detection in the later WFC3 data is debatable. These observations…
Examining molecular clouds in the Galactic Centre region using X-ray reflection spectra simulations
Terrier, R.; Goldwurm, A.; Chernyakova, M. +1 more
In the centre of our Galaxy lies a supermassive black hole, identified with the radio source Sagittarius A⋆. This black hole has an estimated mass of around 4 million solar masses. Although Sagittarius A⋆ is quite dim in terms of total radiated energy, having a luminosity that is a factor of 1010 lower than its Edd…
Oxygen impacts on dipolarization fronts and reconnection rate
Lapenta, Giovanni; Walker, Raymond J.; Ashour-Abdalla, Maha +1 more
Spacecraft observations near a magnetotail X line show that oxygen (O+) ions are minor species during nonstorm substorms, but they can become major species during some of the storm time substorms. Dipolarization fronts (DFs), which are characterized by a sharp increase northward magnetic field in the magnetotail, are commonly observed d…
Far Infrared Variability of Sagittarius A*: 25.5 hr of Monitoring with Herschel
Heinke, C. O.; Dowell, C. D.; Schulz, B. +3 more
Variable emission from Sgr A*, the luminous counterpart to the super-massive black hole at the center of our Galaxy, arises from the innermost portions of the accretion flow. Better characterization of the variability is important for constraining models of the low-luminosity accretion mode powering Sgr A*, and could further our ability to use var…
New Debris Disks in Nearby Young Moving Groups
Ábrahám, P.; Kóspál, Á.; Henning, Th. +5 more
A significant fraction of nearby young moving group members harbor circumstellar debris dust disks. Due to their proximity and youth, these disks are attractive targets for studying the early evolution of debris dust and planetesimal belts. Here we present 70 and 160 µm observations of 31 systems in the β Pic moving group, and in the Tucana-…
Eridania Basin: An ancient paleolake floor as the next landing site for the Mars 2020 rover
Pajola, Maurizio; Carter, John; Pozzobon, Riccardo +5 more
The search for traces of past Martian life is directly connected to ancient paleolakes, where ponding water or low-energy water fluxes were present for long time intervals. The Eridania paleolakes system, located along the 180° meridian, is one of the largest lacustrine environments that were once present on Mars. Morphological features suggest th…