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Dark radiation and inflationary freedom after Planck 2015
Di Valentino, Eleonora; Mena, Olga; Gariazzo, Stefano +2 more
The simplest inflationary models predict a primordial power spectrum (PPS) of the curvature fluctuations that can be described by a power-law function that is nearly scale invariant. It has been shown, however, that the low-multipole spectrum of the cosmic microwave background anisotropies may hint at the presence of some features in the shape of …
Evidence for the Rapid Formation of Low-mass Early-type Galaxies in Dense Environments
Jordán, Andrés; Côté, Patrick; Peng, Eric W. +6 more
We explore the environmental dependence of star formation timescales in low-mass galaxies using the [α/Fe] abundance ratio as an evolutionary clock. We present integrated [α/Fe] measurements for 11 low-mass ({M}\star ∼ {10}9 {M}⊙ ) early-type galaxies (ETGs) with a large range of cluster-centric distance in the Vir…
Ultraviolet diversity of Type Ia Supernovae
Fox, O. D.; Kirshner, R. P.; Foley, Ryan J. +9 more
Ultraviolet (UV) observations of Type Ia supernovae (SNe Ia) probe the outermost layers of the explosion, and UV spectra of SNe Ia are expected to be extremely sensitive to differences in progenitor composition and the details of the explosion. Here, we present the first study of a sample of high signal-to-noise ratio SN Ia spectra that extend blu…
Cyclic variations in O-C diagrams of field RR Lyrae stars as a result of LiTE
Zejda, M.; Skarka, M.; Liška, J. +2 more
This paper presents an extensive overview of known and proposed RR Lyrae stars in binaries. The aim is to revise and extend the list with new Galactic field systems. We utilized maxima timings for 11 RRab type stars with suspicious behaviour from the GEOS data base, and determined maxima timings from data of sky surveys and our own observations. T…
Towards a comprehensive picture of powerful quasars, their host galaxies and quasar winds at z ∼ 0.5
Zakamska, Nadia L.; Wylezalek, Dominika; Obied, Georges +1 more
Luminous type-2 quasars in which the glow from the central black hole is obscured by dust are ideal targets for studying their host galaxies and the quasars' effect on galaxy evolution. Such feedback appears ubiquitous in luminous obscured quasars where high-velocity-ionized nebulae have been found. We present rest-frame yellow-band (∼5000 Å) obse…
Spatial gradients of GCR protons in the inner heliosphere derived from Ulysses COSPIN/KET and PAMELA measurements
Gieseler, J.; Heber, B.
Context. During the transition from solar cycle 23 to 24 from 2006 to 2009, the Sun was in an unusual solar minimum with very low activity over a long period. These exceptional conditions included a very low interplanetary magnetic field (IMF) strength and a high tilt angle, which both play an important role in the modulation of galactic cosmic ra…
Cassini Imaging Science Subsystem observations of Titan's south polar cloud
West, R. A.; Rannou, P.; Lavvas, P. +5 more
In May of 2012 images of Titan obtained by the Cassini Imaging Science Subsystem (ISS) showed a newly-formed cloud patch near the southern pole. The cloud has unusual morphology and texture suggesting that it is formed by condensation at an altitude much higher than expected for any of the known organics in Titan's atmosphere. We measured the alti…
Venus' radar-bright highlands: Different signatures and materials on Ovda Regio and on Maxwell Montes
Treiman, Allan; Harrington, Elise; Sharpton, Virgil
Venus' highlands appear much brighter than its lowland plains in reflected radar, which has been explained by several conflicting hypotheses. We study this transition at higher spatial and elevation resolution than previously possible by combining Magellan synthetic aperture radar (SAR) images with Magellan SAR stereo elevations. We confirm that S…
Reconnection Properties of Large-scale Current Sheets During Coronal Mass Ejection Eruptions
Lynch, B. J.; Guidoni, S. E.; Edmondson, J. K. +1 more
We present a detailed analysis of the properties of magnetic reconnection at large-scale current sheets (CSs) in a high cadence version of the Lynch & Edmondson 2.5D MHD simulation of sympathetic magnetic breakout eruptions from a pseudostreamer source region. We examine the resistive tearing and break-up of the three main CSs into chains of X…
A physical scenario for the high and low X-ray luminosity states in the transitional pulsar PSR J1023+0038
D'Avanzo, P.; Campana, S.; Rea, N. +4 more
The binary system PSR J1023+0038 (J1023) hosts a neutron star and a low-mass companion. J1023 is the best studied transitional pulsar, alternating a faint eclipsing millisecond radio pulsar state to a brighter X-ray active state. At variance with other low-mass X-ray binaries, this active state reaches luminosities of only ~1034 erg s