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Axion Decay and Anisotropy of Near-IR Extragalactic Background Light
Gong, Yan; Cooray, Asantha; Mitchell-Wynne, Ketron +3 more
The extragalactic background light (EBL) is composed of the cumulative radiation from all galaxies and active galactic nuclei over cosmic history. In addition to point sources, the EBL also contains information from diffuse sources of radiation. The angular power spectra of the near-infrared intensities could contain additional signals, and a comp…
GeMS MCAO observations of the Galactic globular cluster NGC 2808: the absolute age
Massari, D.; Stetson, P. B.; Bono, G. +7 more
Context. Globular clusters are the oldest stellar systems in the Milky Way, and they probe the early epoch of the Galaxy formation. However, the uncertainties on their absolute age are still too large to soundly constrain how the Galactic structures have assembled.
Aims: The aim of this work is to obtain an accurate estimate of the absolute a…
Anatomy of the AGN in NGC 5548. VII. Swift study of obscuration and broadband continuum variability
Kaastra, J. S.; Kriss, G. A.; Bianchi, S. +16 more
We present our investigation into the long-term variability of the X-ray obscuration and optical-UV-X-ray continuum in the Seyfert 1 galaxy NGC 5548. In 2013 and 2014, the Swift observatory monitored NGC 5548 on average every day or two, with archival observations reaching back to 2005, totalling about 670 ks of observing time. Both broadband spec…
Typical Profiles and Distributions of Plasma and Magnetic Field Parameters in Magnetic Clouds at 1 AU
Mierla, M.; Zhukov, A. N.; Rodriguez, L. +9 more
Magnetic clouds (MCs) are a subset of interplanetary coronal mass ejections (ICMEs). They are important because of their simple internal magnetic field configuration, which resembles a magnetic flux rope, and because they represent one of the most geoeffective types of solar transients. In this study, we analyze their internal structure using a su…
The Spectral Energy Distribution of the Coldest Known Brown Dwarf
Luhman, K. L.; Esplin, T. L.
WISE J085510.83-071442.5 (hereafter WISE 0855-0714) is the coldest known brown dwarf (∼250 K) and the fourth-closest known system to the Sun (2.2 pc). It has been previously detected only in the J band and two mid-IR bands. To better measure its spectral energy distribution (SED), we have performed deep imaging of WISE 0855-0714 in six optical and…
Star formation efficiency along the radio jet in Centaurus A
Heywood, I.; Combes, F.; Salomé, P. +2 more
NGC 5128 (also known as Centaurus A) is the most nearby powerful AGN, widely studied at all wavelengths. Molecular gas has been found in the halo at a distance of ~ 20 kpc from the galaxy center, associated with H I shells, through CO line detection at SEST (Charmandaris et al. 2000, A&A, 356, L1). The molecular gas lies inside some IR and UV …
On the Misalignment between Chromospheric Features and the Magnetic Field on the Sun
Martínez-Sykora, Juan; De Pontieu, Bart; Hansteen, Viggo +1 more
Observations of the upper chromosphere show an enormous amount of intricate fine structure. Much of this comes in the form of linear features, which are most often assumed to be well aligned with the direction of the magnetic field in the low plasma β regime that is thought to dominate the upper chromosphere. We use advanced radiative magnetohydro…
High-energy gamma-ray observations of the accreting black hole V404 Cygni during its 2015 June outburst
Rodriguez, J.; Fender, R.; Dubus, G. +7 more
We report on Fermi/Large Area Telescope observations of the accreting black hole low-mass X-ray binary V404 Cygni during its outburst in 2015 June-July. Detailed analyses reveal a possible excess of γ-ray emission on 2015 26 June, with a very soft spectrum above 100 MeV, at a position consistent with the direction of V404 Cyg (within the 95 per ce…
Detection of Three Gamma-ray Burst Host Galaxies at z ∼ 6
Stocke, J. T.; Shull, J. M.; Bremer, M. +17 more
Long-duration gamma-ray bursts (GRBs) allow us to pinpoint and study star-forming galaxies in the early universe, thanks to their orders of magnitude brighter peak luminosities compared to other astrophysical sources, and their association with the deaths of massive stars. We present Hubble Space Telescope Wide Field Camera 3 detections of three S…
Boron Abundances Across the “Li-Be Dip” in the Hyades Cluster
Deliyannis, Constantine P.; Somers, Garrett; Pinsonneault, Marc H. +3 more
Dramatic deficiencies of Li in the mid-F dwarf stars of the Hyades cluster were discovered by Boesgaard & Tripicco. Boesgaard & King discovered corresponding, but smaller, deficiencies in Be in the same narrow temperature region in the Hyades. Using the Space Telescope Imaging Spectrograph on the Hubble Space Telescope, we investigate B ab…