962 research outputs found
Preconcentration and Heavy Minerals Separation with Low Grade Beach Sand Sample from Narsapur Coast, West Godavari District, Andhra Pradesh
India is blessed with large reserves of strategic and economically important heavy minerals such as Ilmenite, Rutile, Leucoxene, Zircon, Monazite, Garnet and Sillimanite.
These deposits are mostly located in the coastal stretches of peninsular India covering states of Orissa, Andhra pradesh, Tamil nadu, Kerala and Maharastra
HST and Spitzer Observations of the Host Galaxy of GRB 050904: A Metal-Enriched, Dusty Starburst at z=6.295
We present deep Hubble Space Telescope and Spitzer Space Telescope
observations of the host galaxy of GRB 050904 at z=6.295. The host is detected
in the H-band and marginally at 3.6 micron. From these detections, and limits
in the z'-band and 4.5 micron, we infer an extinction-corrected absolute
magnitude, M(UV)=-20.7 mag, or ~L*, a substantial star formation rate of 15
solar masses per year, and a stellar mass of a few 10^9 solar masses. A
comparison to the published sample of spectroscopically-confirmed galaxies at
z>5.5 reveals that the host of GRB 050904 would evade detection and/or
confirmation in any of the current surveys due to the lack of detectable
Ly-alpha emission, which is likely the result of dust extinction (A[1200]~1.5
mag). This suggests that not all luminous starburst galaxies at z~6 are
currently being accounted for. Most importantly, using the metallicity of
Z~0.05 solar inferred from the afterglow absorption spectrum, our observations
indicate for the first time that the observed evolution in the mass- and
luminosity-metallicity relations from z=0 to z~2 continues on to z>6. The ease
of measuring redshifts and metallicities from the afterglow emission suggests
that in tandem with the next generation ground- and space-based telescopes, a
GRB mission with dedicated near-IR follow-up can provide unique information on
the evolution of stars and galaxies through the epoch of re-ionization.Comment: Submitted to ApJ; 11 pages, 5 figures; A high-resolution version of
figure 1 can be found at http://www.ociw.edu/~eberger/fig1.050904.berger.ep
AEGIS: Infrared Spectroscopy of An Infrared Luminous Lyman Break Galaxy at z=3.01
We report the detection of rest--frame 6.2 and 7.7 \micron emission features
arising from Polycyclic Aromatic Hydrocarbons (PAH) in the Spitzer/IRS spectrum
of an infrared-luminous Lyman break galaxy at z=3.01. This is currently the
highest redshift galaxy where these PAH emission features have been detected.
The total infrared luminosity inferred from the MIPS 24 \micron and radio flux
density is 2 L, which qualifies this object as a
so--called hyperluminous infrared galaxy (HyLIRG). However, unlike local
HyLIRGs which are generally associated with QSO/AGNs and have weak or absent
PAH emission features, this HyLIRG has very strong 6.2 and 7.7 \micron PAH
emission. We argue that intense star formation dominates the infrared emission
of this source, although we cannot rule out the presence of a deeply obscured
AGN. This LBG appears to be a distorted system in the HST ACS F606W and F814W
images, possibly indicating that a significant merger or interaction is driving
the large IR luminosity
Differential Calculi on Some Quantum Prehomogeneous Vector Spaces
This paper is devoted to study of differential calculi over quadratic
algebras, which arise in the theory of quantum bounded symmetric domains. We
prove that in the quantum case dimensions of the homogeneous components of the
graded vector spaces of k-forms are the same as in the classical case. This
result is well-known for quantum matrices.
The quadratic algebras, which we consider in the present paper, are
q-analogues of the polynomial algebras on prehomogeneous vector spaces of
commutative parabolic type. This enables us to prove that the de Rham complex
is isomorphic to the dual of a quantum analogue of the generalized
Bernstein-Gelfand-Gelfand resolution.Comment: LaTeX2e, 51 pages; changed conten
Application of Resonance Perturbation Theory to Dynamics of Magnetization in Spin Systems Interacting with Local and Collective Bosonic Reservoirs
We apply our recently developed resonance perturbation theory to describe the
dynamics of magnetization in paramagnetic spin systems interacting
simultaneously with local and collective bosonic environments. We derive
explicit expressions for the evolution of the reduced density matrix elements.
This allows us to calculate explicitly the dynamics of the macroscopic
magnetization, including characteristic relaxation and dephasing time-scales.
We demonstrate that collective effects (i) do not influence the character of
the relaxation processes but merely renormalize the relaxation times, and (ii)
significantly modify the dephasing times, leading in some cases to a
complicated (time inhomogeneous) dynamics of the transverse magnetization,
governed by an effective time-dependent magnetic field
Infrared Imaging of GRB 970508
We have observed the field of the gamma-ray burst GRB 970508 at infrared wavelengths (2.2 μm) and have found a variable source coincident with the visible transient thought to be associated with the burst. The source was decaying in brightness with Ks magnitudes of 18.2±0.1, 18.8±0.1, and 19.0±0.3 mag on May 13.25, 16.25, and 20.21 UT, respectively. A 1 σ upper limit of K=21.3 mag was obtained for the brightness of the source on June 14.27 UT. The infrared light curve during this period is consistent with a ~t^(-1.2) power law, similar to the visible light curve. We do not find evidence for extended structure around the burst, as has been claimed for GRB 970228, and we obtain an upper limit of 0.04L_* for the luminosity of an underlying galaxy at the position of the infrared transient
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