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Cosmological implications of different baryon acoustic oscillation data
Li, Miao; Wang, Shuang; Hu, YaZhou
In this work, we explore the cosmological implications of different baryon acoustic oscillation (BAO) data, including the BAO data extracted by using the spherically averaged one-dimensional galaxy clustering (GC) statistics (hereafter BAO1) and the BAO data obtained by using the anisotropic two-dimensional GC statistics (hereafter BAO2). To make …
Unveiling slim accretion disc in AGN through X-ray and Infrared observations
Kaspi, Shai; Ho, Luis C.; Bian, Wei-Hao +7 more
In this work, which is a continuation of Castelló-Mor et al., we present new X-ray and infrared (IR) data for a sample of active galactic nuclei (AGN) covering a wide range in Eddington ratio over a small luminosity range. In particular, we rigorously explore the dependence of the optical-to-X-ray spectral index αOX and the IR-to-optica…
Magnetic Separatrix as the Source Region of the Plasma Supply for an Active-region Filament
Cao, Wenda; Yang, K.; Chen, P. F. +2 more
Solar filaments can be formed via chromospheric evaporation followed by condensation in the corona or by the direct injection of cool plasma from the chromosphere to the corona. We here confirm with high-resolution Hα data observed by the 1.6 m New Solar Telescope of the Big Bear Solar Observatory on 2015 August 21 that an active-region filament i…
X-ray observations of FO Aqr during the 2016 low state
Mukai, K.; Garnavich, P. M.; Kennedy, M. R. +5 more
We present the first ever X-ray data taken of an intermediate polar, FO Aquarii (FO Aqr), when in a low accretion state and during the subsequent recovery. Both the Swift and Chandra X-ray data taken during the low accretion state in 2016 July show a softer spectrum when compared to archival data taken when FO Aqr was in a high state. The X-ray sp…
Sunspot Light Walls Suppressed by Nearby Brightenings
Hou, Yijun; Yang, Shuhong; Zhang, Jun +3 more
Light walls, as ensembles of oscillating bright structures rooted in sunspot light bridges, have not been well studied, although they are important for understanding sunspot properties. Using the Interface Region Imaging Spectrograph and Solar Dynamics Observatory observations, here we study the evolution of two oscillating light walls each within…
Observational signatures of past mass-exchange episodes in massive binaries: the case of LSS 3074
Gosset, E.; Rauw, G.; Manfroid, J. +4 more
Context. The role of mass and momentum exchanges in close massive binaries is very important in the subsequent evolution of the components. Such exchanges produce several observational signatures such as asynchronous rotation and altered chemical compositions, that remain after the stars detach again.
Aims: We investigated these effects for t…
Probing the Metal Enrichment of the Intergalactic Medium at z = 5-6 Using the Hubble Space Telescope
Fan, Xiaohui; Cai, Zheng; Finlator, Kristian +2 more
We test the galactic outflow model by probing associated galaxies of four strong intergalactic C IV absorbers at z = 5-6 using the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) ramp narrowband filters. The four strong C IV absorbers reside at z = 5.74, 5.52, 4.95, and 4.87, with column densities ranging from N C IV = 1…
Far-ultraviolet observation of the globular cluster NGC 6397
Knigge, C.; Shara, M.; Dieball, A. +2 more
We present an observational far-ultraviolet (FUV) and near-ultraviolet (NUV) study of the core region of the globular cluster (GC) NGC 6397. The observations were obtained with the Space Telescope Imaging Spectrograph (STIS, FUV) and the Wide Field Camera 3 (NUV) on board the Hubble Space Telescope. Here, we focus on the UV-bright stellar populati…
Direct probe of the inner accretion flow around the supermassive black hole in NGC 2617
Costantini, E.; Miniutti, G.; Motta, S. E. +12 more
Aims: NGC 2617 is a nearby (z 0.01) active galaxy that recently switched from being a Seyfert 1.8 to be a Seyfert 1.0. At the same time, it underwent a strong increase of X-ray flux by one order of magnitude with respect to archival measurements. We characterise the X-ray spectral and timing properties of NGC 2617 with the aim of studying the…
Variability of the symbiotic X-ray binary GX 1+4. Enhanced activity near periastron passage
Iłkiewicz, Krystian; Mikołajewska, Joanna; Monard, Berto
Context. GX 1+4 belongs to a rare class of X-ray binaries with red giant donors, symbiotic X-ray binaries. It has a history of complicated variability on multiple timescales in the optical light and X-rays. The nature of this variability remains poorly understood.
Aims: We aim to study variability of GX 1+4 on long timescale in X-ray and opti…