2,162 research outputs found
Detection of a methanol megamaser in a major-merger galaxy
We have detected emission from both the 4_{-1}-3_{0} E (36.2~GHz) class I and
7_{-2}-8_{-1} E (37.7~GHz) class II methanol transitions towards the centre of
the closest ultra-luminous infrared galaxy Arp 220. The emission in both the
methanol transitions show narrow spectral features and have luminosities
approximately 8 orders of magnitude stronger than that observed from typical
class I methanol masers observed in Galactic star formation regions. The
emission is also orders of magnitude stronger than the expected intensity of
thermal emission from these transitions and based on these findings we suggest
that the emission from the two transitions are masers. These observations
provides the first detection of a methanol megamaser in the 36.2 and 37.7 GHz
transitions and represents only the second detection of a methanol megamaser,
following the recent report of an 84 GHz methanol megamaser in NGC1068. We find
the methanol megamasers are significantly offset from the nuclear region and
arise towards regions where there is Ha emission, suggesting that it is
associated with starburst activity. The high degree of correlation between the
spatial distribution of the 36.2 GHz methanol and X-ray plume emission suggests
that the production of strong extragalactic class I methanol masers is related
to galactic outflow driven shocks and perhaps cosmic rays. In contrast to OH
and H2O megamasers which originate close to the nucleus, methanol megamasers
provide a new probe of feedback (e.g. outflows) processes on larger-scales and
of star formation beyond the circumnuclear starburst regions of active
galaxies.Comment: Accepted for publication in ApJ
Draft Genome Sequence of Streptomyces sp. Strain CT34, Isolated from a Ghanaian Soil Sample
Copyright © 2015 Zhai et al. This work was supported by the China “973” program (2012CB721001), the “863” Program (2012AA092201), the National Natural Science Foundation of China (31170467), and the EU FP7 project PharmaSea (312184). K.K., M.J., and H.D. thank the Royal Society–Leverhulme Trust Africa for the financial support (award AA090088) that enabled the sampling of sediments and subsequent isolation of this unique Ghanaian strain.Non peer reviewedPublisher PD
Fivebranes from gauge theory
We study theories with sixteen supercharges and a discrete energy spectrum.
One class of theories has symmetry group . They arise as truncations
of super Yang Mills. They include the plane wave matrix model, 2+1
super Yang Mills on and super Yang Mills on . We explain how to obtain their gravity duals in a unified way.
We explore the regions of the geometry that are relevant for the study of some
1/2 BPS and near BPS states. This leads to a class of two dimensional (4,4)
supersymmetric sigma models with non-zero flux, including a massive
deformed WZW model. We show how to match some features of the string spectrum
with the Yang Mills theory.
The other class of theories are also connected to super Yang
Mills and arise by making some of the transverse scalars compact. Their vacua
are characterized by a 2d Yang Mills theory or 3d Chern Simons theory. These
theories realize peculiar superpoincare symmetry algebras in 2+1 or 1+1
dimensions with "non-central" charges. We finally discuss gravity duals of
super Yang Mills on .Comment: 50+24 pages, 9 figures, latex. v2: typos corrected, references adde
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