1,961 research outputs found
Revealing A Head-on Major Merger in the Nearby NGC 6338 Group with Chandra and VLA observations
By analyzing the Chandra archival data of the nearby NGC 6338 galaxy group,
we identify two X-ray bright clumps (N-clump and S-clump) within the central
100 kpc, and detect an arc-like X-ray brightness discontinuity at the south
boundary of the N-clump, which is defined as a cold front with a gas flow Mach
number of M<0.8. Furthermore, at the north-east boundary of the S-clump
(dominated by galaxy NGC 6338) another X-ray edge is detected that corresponds
to a weaker cold front. Therefore, the two clumps are approaching each other
approximately from opposite directions, and the group is undergoing a head-on
collision that is in a stage of pre-core passage. This merger scenario is also
supported by the study of the line-of-sight velocity distribution of the group
member galaxies. The merger mass ratio is about 1:1.8 as estimated from the
central gas temperature of the two clumps, which suggests the merger is most
likely to be a major merger. We also analyze the VLA 1.4 and 4.9 GHz radio
data, but we do not detect any extended radio emission that is associated with
the merger.Comment: Accepted by Ap
(Anthracen-9-yl)(piperidin-1-yl)Âmethanone
The title compound, C20H19NO, is a substructure of CP-640186, a potent inhibitor of mammalian acetyl-coenzyme A carboxylÂases. In the crystal structure, the amide group forms a dihedral angle of 87.0 (1)° with the plane of the anthracene unit and the piperidine ring adopts a chair conformation. MolÂecules are arranged into layers parallel to (100) and adjacent anthracene units within layers form dihedral angles of 13.2 (1)°. C—H⋯O interÂactions from the piperidine rings to the C=O group of the amide are observed between layers
Gap Anisotropy in Iron-Based Superconductors: A Point-Contact Andreev Reflection Study of BaFeNiAs Single Crystals
We report a systematic investigation on c-axis point-contact Andreev
reflection (PCAR) in BaFeNiAs superconducting single crystals
from underdoped to overdoped regions (0.075 ). At optimal
doping () the PCAR spectrum feature the structures of two
superconducting gap and electron-boson coupling mode. In the scenario,
quantitative analysis using a generalized Blonder-Tinkham-Klapwijk (BTK)
formalism with two gaps: one isotropic and another angle dependent, suggest a
nodeless state in strong-coupling limit with gap minima on the Fermi surfaces.
Upon crossing above the optimal doping (), the PCAR spectrum show an
in-gap sharp narrow peak at low bias, in contrast to the case of underdoped
samples (), signaling the onset of deepened gap minima or nodes in the
superconducting gap. This result provides evidence of the modulation of the gap
amplitude with doping concentration, consistent with the calculations for the
orbital dependent pair interaction mediated by the antiferromagnetic spin
fluctuations.Comment: 5 pages, 4 figure
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