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Measurements of Photospheric and Chromospheric Magnetic Fields
Gosain, Sanjay; Lagg, Andreas; Lites, Bruce +2 more
The Sun is replete with magnetic fields, with sunspots, pores and plage regions being their most prominent representatives on the solar surface. But even far away from these active regions, magnetic fields are ubiquitous. To a large extent, their importance for the thermodynamics in the solar photosphere is determined by the total magnetic flux. W…
New constraints on the average escape fraction of Lyman continuum radiation in z 4 galaxies from the VIMOS Ultra Deep Survey (VUDS)
Maccagni, D.; Schaerer, D.; Thomas, R. +20 more
Context. Determining the average fraction of Lyman continuum (LyC) photons escaping high redshift galaxies is essential for understanding how reionization proceeded in the z> 6 Universe.
Aims: We want to measure the LyC signal from a sample of sources in the Chandra Deep Field South (CDFS) and COSMOS fields for which ultra-deep VIMOS spect…
Probing the intra-group medium of a z = 0.28 galaxy group
Tejos, N.; Morris, S. L.; Cantalupo, S. +4 more
We present new MUSE observations of a galaxy group probed by a background quasar. The quasar sightline passes between multiple z = 0.28 galaxies, whilst showing at the same redshift low-ionized metal line species, including Ca II, Mg I, Mg II and Fe II. Based on the galaxy redshifts measured from the MUSE data, we estimate the galaxies to be part …
Astrometric Calibration and Performance of the Dark Energy Camera
Benoit-Lévy, A.; Bechtol, K.; Smith, M. +54 more
We characterize the ability of the Dark Energy Camera (DECam) to perform relative astrometry across its 500 Mpix, 3-deg2 science field of view and across four years of operation. This is done using internal comparisons of ∼4 × 107 measurements of high signal-to-noise ratio stellar images obtained in repeat visits to fields of…
Major mergers are not significant drivers of star formation or morphological transformation around the epoch of peak cosmic star formation
Conselice, C. J.; Hartley, W.; Mortlock, A. +2 more
We investigate the contribution of major mergers (mass ratios >1: 5) to stellar mass growth and morphological transformations around the epoch of peak cosmic star formation (z ∼ 2). We visually classify a complete sample of massive (M > 1010M⊙) galaxies at this epoch, drawn from the Cosmic Assembly Near-infrared Deep Ex…
Modeling the Historical Flux of Planetary Impactors
Nesvorný, David; Roig, Fernando; Bottke, William F.
The impact cratering record of the Moon and the terrestrial planets provides important clues about the formation and evolution of the solar system. Especially intriguing is the epoch ≃3.8-3.9 Gyr ago (Ga), known as the Late Heavy Bombardment (LHB), when the youngest lunar basins such as Imbrium and Orientale formed. The LHB was suggested to origin…
VoIgt profile Parameter Estimation Routine (viper): H I photoionization rate at z < 0.5
Khaire, Vikram; Srianand, Raghunathan; Choudhury, Tirthankar Roy +1 more
We have developed a parallel code called the VoIgt profile Parameter Estimation Routine (viper) for automatically fitting the H I Lyα forest seen in the spectra of quasi-stellar objects (QSOs). We obtained the H I column density distribution function (CDDF) and linewidth (b) parameter distribution for z < 0.45 using spectra of 82 QSOs obtained …
Cosmic viscosity as a remedy for tension between PLANCK and LSS data
Anand, Sampurn; Chaubal, Prakrut; Mazumdar, Arindam +1 more
Measurements of σ8 from large scale structure observations show a discordance with the extrapolated σ8 from Planck CMB parameters using ΛCDM cosmology. Similar discordance is found in the value of H0 and Ωm. In this paper, we show that the presence of viscosity, shear or bulk or combination of both, can …
Elongation of Flare Ribbons
Qiu, Jiong; Longcope, Dana W.; Cassak, Paul A. +1 more
We present an analysis of the apparent elongation motion of flare ribbons along the polarity inversion line (PIL), as well as the shear of flare loops in several two-ribbon flares. Flare ribbons and loops spread along the PIL at a speed ranging from a few to a hundred km s-1. The shear measured from conjugate footpoints is consistent wi…
Different Origins or Different Evolutions? Decoding the Spectral Diversity Among C-type Asteroids
Jorda, L.; Lamy, P.; Groussin, O. +15 more
Anhydrous pyroxene-rich interplanetary dust particles (IDPs) have been proposed as surface analogs for about two-thirds of all C-complex asteroids. However, this suggestion appears to be inconsistent with the presence of hydrated silicates on the surfaces of some of these asteroids, including Ceres. Here, we report the presence of enstatite (pyrox…