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Suzaku monitoring of the Wolf-Rayet binary WR 140 around periastron passage: An approach for quantifying the wind parameters
Hamaguchi, Kenji; Sugawara, Yasuharu; Maeda, Yoshitomo +7 more
Suzaku observations of the Wolf-Rayet (W-R) binary WR 140 (WC7pd+O5.5fc) were made at four different times around periastron passage in 2009 January. The spectra changed in shape and flux with the phase. As periastron approached, the column density of the low-energy absorption increased, which indicates that the emission from the wind-wind collisi…
A Likely Millisecond Pulsar Binary Counterpart for Fermi Source 2FGL J2039.6-5620
Romani, Roger W.
We have identified an optical/X-ray binary with an orbital period of Pb = 5.47 hr as the likely counterpart of the Fermi source 2FGL J2039.6-5620. GROND, SOAR, and DES observations provide an accurate orbital period and allow us to compare to the light curve of an archival XMM exposure. Like many short-period optical/X-ray binaries asso…
Dynamics of On-disk Plumes as Observed with the Interface Region Imaging Spectrograph, the Atmospheric Imaging Assembly, and the Helioseismic and Magnetic Imager
Krishna Prasad, S.; Pant, Vaibhav; Dolla, Laurent +3 more
We examine the role of small-scale transients in the formation and evolution of solar coronal plumes. We study the dynamics of plume footpoints seen in the vicinity of a coronal hole using the Atmospheric Imaging Assembly (AIA) images, the Helioseismic and Magnetic Imager magnetogram on board the Solar Dynamics Observatory and spectroscopic data f…
Constraints on the early and late integrated Sachs-Wolfe effects from the Planck 2015 cosmic microwave background anisotropies in the angular power spectra
Melchiorri, Alessandro; Cabass, Giovanni; Gerbino, Martina +3 more
The integrated Sachs-Wolfe (ISW) effect predicts additional anisotropies in the cosmic microwave background (CMB) due to time variation of the gravitational potential when the expansion of the Universe is not matter dominated. The ISW effect is therefore expected in the early Universe, due to the presence of relativistic particles at recombination…
Searching for coherent pulsations in ultraluminous X-ray sources
Santangelo, A.; Ducci, L.; Doroshenko, V.
Luminosities of ultraluminous X-ray sources (ULXs) are uncomfortably large when compared to the Eddington limit for isotropic accretion onto stellar-mass object. Most often either supercritical accretion onto stellar mass black holes or accretion onto intermediate mass black holes is invoked the high luminosities of ULXs. However, the recent disco…
Ground-based Paα Narrow-band Imaging of Local Luminous Infrared Galaxies. I. Star Formation Rates and Surface Densities
Tamura, Yoichi; Kohno, Kotaro; Tanabé, Toshihiko +33 more
Luminous infrared galaxies (LIRGs) are enshrouded by a large amount of dust produced by their active star formation, and it is difficult to measure their activity in optical wavelengths. We have carried out Paα narrow-band imaging observations of 38 nearby star forming galaxies including 33 LIRGs listed in the IRAS Revised Bright Galaxy Sample cat…
Surfing gravitational waves: can bigravity survive growing tensor modes?
Amendola, Luca; Pettorino, Valeria; Könnig, Frank +2 more
The theory of bigravity offers one of the simplest possibilities to describe a massive graviton while having self-accelerating cosmological solutions without a cosmological constant. However, it has been shown recently that bigravity is affected by early-time fast growing modes on the tensor sector. Here we argue that we can only trust the linear …
Dynamics in Sunspot Umbra as Seen in New Solar Telescope and Interface Region Imaging Spectrograph Data
Yurchyshyn, V.; Kilcik, A.; Abramenko, V.
We analyze sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST) for the main sunspot in NOAA AR 11836. We report that the difference between the shock arrival times as measured by the Mg II k 2796.35 Å and Si IV 1393.76 Å line form…
Birkeland current effects on high-latitude ground magnetic field perturbations
Anderson, B. J.; Snekvik, K.; Østgaard, N. +8 more
Magnetic perturbations on ground at high latitudes are directly associated only with the divergence-free component of the height-integrated horizontal ionospheric current, J⊥,df. Here we show how J⊥,df can be expressed as the total horizontal current J⊥ minus its curl-free component, the latter being completely det…
Suzaku studies of the supernova remnant CTB 109 hosting the magnetar 1E 2259+586
Enoto, Teruaki; Makishima, Kazuo; Kaneda, Hidehiro +4 more
Ages of the magnetar 1E 2259+586 and the associated supernova remnant CTB 109 were studied. Analyzing the Suzaku data of CTB 109, its age was estimated to be ∼ 14 kyr, which is much younger than the measured characteristic age of 1E 2259+586, 230 kyr. This reconfirms the previously reported age discrepancy of this magnetar/remnant association, and…