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Broadband Radio Polarimetry and Faraday Rotation of 563 Extragalactic Radio Sources
Gaensler, B. M.; Franzen, T. M. O.; Anderson, C. S. +1 more
We present a broadband spectropolarimetric survey of 563 discrete, mostly unresolved radio sources between 1.3 and 2.0 GHz using data taken with the Australia Telescope Compact Array. We have used rotation-measure synthesis to identify Faraday-complex polarized sources, those objects whose frequency-dependent polarization behavior indicates the pr…
Non-local gravity and comparison with observational datasets
Kunz, Martin; Pettorino, Valeria; Dirian, Yves +2 more
We study the cosmological predictions of two recently proposed non-local modifications of General Relativity. Both models have the same number of parameters as ΛCDM, with a mass parameter m replacing the cosmological constant. We implement the cosmological perturbations of the non-local models into a modification of the CLASS Boltzmann code, and w…
HST Rotational Spectral Mapping of Two L-type Brown Dwarfs: Variability in and out of Water Bands indicates High-altitude Haze Layers
Metchev, Stanimir; Showman, Adam P.; Apai, Dániel +13 more
We present time-resolved near-infrared spectroscopy of two L5 dwarfs, 2MASS J18212815+1414010 and 2MASS J15074759-1627386, observed with the Wide Field Camera 3 instrument on the Hubble Space Telescope (HST). We study the wavelength dependence of rotation-modulated flux variations between 1.1 µm and 1.7 µm. We find that the water absor…
Magnetic field-gas density relation and observational implications revisited
Panopoulou, G. V.; Pavlidou, V.; Tassis, K. +2 more
We revisit the relation between magnetic-field strength (B) and gas density (ρ) for contracting interstellar clouds and fragments (or, cores), which is central in observationally determining the dynamical importance of magnetic fields in cloud evolution and star formation. Recently, it has been claimed that a relation B ∝ ρ2/3 is statis…
Improved limits on sterile neutrino dark matter using full-sky Fermi Gamma-ray Burst Monitor data
Ng, Kenny C. Y.; Horiuchi, Shunsaku; Gaskins, Jennifer M. +2 more
A sterile neutrino of ∼keV mass is a well-motivated dark matter candidate. Its decay generates an x-ray line that offers a unique target for x-ray telescopes. For the first time, we use the Gamma-ray Burst Monitor (GBM) onboard the Fermi Gamma-Ray Space Telescope to search for sterile neutrino decay lines; our analysis covers the energy range 10-2…
Gone without a bang: an archival HST survey for disappearing massive stars
Gilmore, Gerard; Reynolds, Thomas M.; Fraser, Morgan
It has been argued that a substantial fraction of massive stars may end their lives without an optically bright supernova (SN), but rather collapse to form a black hole. Such an event would not be detected by current SN surveys, which are focused on finding bright transients. Kochanek et al. proposed a novel survey for such events, using repeated …
Electron acceleration in the dipolarization front driven by magnetic reconnection
Wang, Shui; Huang, Can; Lu, Quanming +2 more
A large-scale two-dimensional (2-D) particle-in-cell simulation is performed in this paper to investigate electron acceleration in the dipolarization front (DF) region during magnetic reconnection. It is found that the DF is mainly driven by an ion outflow which also generates a positive potential region behind the DF. The DF propagates with an al…
On the Origin of Mid-latitude Fast Wind: Challenging the Two-state Solar Wind Paradigm
Landi, Enrico; Zurbuchen, Thomas H.; Lepri, Susan T. +2 more
The bimodal paradigm of solar wind describes a slow solar wind situated near the heliospheric current sheet while a fast wind overexpands from the poles to fill in the remainder of the heliosphere. In this paper, we challenge this paradigm and focus here on mid-latitude wind using three fast-latitude passes completed by the Ulysses spacecraft. Bas…
Mass without radiation: Heavily obscured AGNs, the X-ray background, and the black hole mass density
Marconi, A.; Gilli, R.; Comastri, A. +2 more
A recent revision of black hole scaling relations indicate that the local mass density in black holes should be five times higher than previously determined values. The local black hole mass density is connected to the mean radiative efficiency of accretion through the time integral of the Active Galactic Nuclei (AGN) volume density and a signific…
Distribution of water around the nucleus of comet 67P/Churyumov-Gerasimenko at 3.4 AU from the Sun as seen by the MIRO instrument on Rosetta
Hartogh, P.; Lellouch, E.; Crovisier, J. +13 more
The Microwave Instrument on the Rosetta Orbiter (MIRO) has been observing the coma of comet 67P/Churyumov-Gerasimenko almost continuously since June 2014 at wavelengths near 0.53 mm. We present here a map of the water column density in the inner coma (within 3 km from nucleus center) when the comet was at 3.4 AU from the Sun. Based on the analysis…