15,608 research outputs found
High energy electrons and emission of the omnidirectional synchrotron radiation in radio frequency and X-ray regions
High energy electrons and emission of galactic, omnidirectional synchrotron radiation in radio frequency and X rays region
Measurement of the Charged Splash and Re-entrant Albedo of the Cosmic Radiation
Proton and electron balloon measurements of splash and re-entrant cosmic ray albed
Proton albedo spectrum observation in low latitude region at Hyderabad, India
The flux and the energy spectrum of low energy (30-100 MeV) proton albedos, have been observed for the first time in a low latitude region, over Hyderabad, India. The preliminary results, based on the quick look data acquisition and display system are presented. A charged particle telescope, capable of distinguishing singly charged particles such as electrons, muons, protons in low energy region, records the data of both upward as well as downward moving particles. Thus spectra of splash and re-entrant albedo protons have been recorded simultaneously in a high altitude Balloon flight carried out on 8th December, 1985, over Hyderabad, India. Balloon floated at an latitude of approx. 37 km (4 mb)
Observation of energy spectrum of electron albedo in low latitude region at Hyderabad, India
The preliminary results are presented of the measurement of the energy spectrum of low energy (5-24 MeV) albedo electrons, moving upward as well as downwards, at about 37 km (-4 mb) altitude, over Hyderabad, India, in low latitude region. The flux and energy spectrum was observed by a bi-directional, multidetector charged particle telescope which was flown in a high altitude balloon on 8th December 1984. Results based on a quick look data acquisition and analysis system are presented here
A bi-directional charged particle telescope to observe flux, energy spectrum and angular distribution of relativistic and non-relativistic particles
A Charged Particle Telescope (CPT) was designed, fabricated and calibrated to make the following observations: (1) discrimination between various singly charged particles, e.g., electrons, muons and protons, in about 5 to 100 MeV energy range; (2) measurement of the flux and the energy of the charged particles incident to the telescope from two opposite directions and stopping in the telescope, thus obtaining flux and energy spectrum of downward and upward moving charged particles; and (3) measurement of the broad angular distribution of selected particles as a function of azimuthal angle. This telescope can be used to study low energy electron, muon and proton energy spectra. The experiment was flown in a high altitude balloon from Hyderabad, India, in December 1984. This same equipment is also useful in ground level electron, muon spectrum study
Field theoretic calculation of scalar turbulence
The cascade rate of passive scalar and Bachelor's constant in scalar
turbulence are calculated using the flux formula. This calculation is done to
first order in perturbation series. Batchelor's constant in three dimension is
found to be approximately 1.25. In higher dimension, the constant increases as
.Comment: RevTex4, publ. in Int. J. Mod. Phy. B, v.15, p.3419, 200
Calculation of renormalized viscosity and resistivity in magnetohydrodynamic turbulence
A self-consistent renormalization (RG) scheme has been applied to nonhelical
magnetohydrodynamic turbulence with normalized cross helicity and
. Kolmogorov's 5/3 powerlaw is assumed in order to compute the
renormalized parameters. It has been shown that the RG fixed point is stable
for . The renormalized viscosity and resistivity
have been calculated, and they are found to be positive for all
parameter regimes. For and large Alfv\'{e}n ratio (ratio of
kinetic and magnetic energies) , and . As
is decreased, increases and decreases, untill where both and are approximately zero. For large ,
both and vary as . The renormalized parameters for
the case are also reported.Comment: 19 pages REVTEX, 3 ps files (Phys. Plasmas, v8, 3945, 2001
HST imaging of hyperluminous infrared galaxies
We present HST WFPC2 I band imaging for a sample of 9 Hyperluminous Infrared
Galaxies spanning a redshift range 0.45 < z < 1.34. Three of the sample have
morphologies showing evidence for interactions, six are QSOs. Host galaxies in
the QSOs are reliably detected out to z ~ 0.8. The detected QSO host galaxies
have an elliptical morphology with scalelengths spanning 6.5 < r_{e}(Kpc) < 88
and absolute k corrected magnitudes spanning -24.5 < M_{I} < -25.2. There is no
clear correlation between the IR power source and the optical morphology. None
of the sources in the sample, including F15307+3252, show any evidence for
gravitational lensing. We infer that the IR luminosities are thus real. Based
on these results, and previous studies of HLIRGs, we conclude that this class
of object is broadly consistent with being a simple extrapolation of the ULIRG
population to higher luminosities; ULIRGs being mainly violently interacting
systems powered by starbursts and/or AGN. Only a small number of sources whose
infrared luminosities exceed 10^{13}Lsun are intrinsically less luminous
objects which have been boosted by gravitational lensing.Comment: 16 Pages. Accepted for publication in MNRA
Sub-millimetre observations of hyperluminous infrared galaxies
We present sub-mm photometry for 11 Hyperluminous Infrared Galaxies (HLIRGs)
and use radiative transfer models for starbursts and AGN to investigate the IR
emission. In all sources both a starburst and AGN are required to explain the
IR emission. The mean starburst fraction is 35%, with a range spanning 80%
starburst dominated to 80% AGN dominated. In all cases the starburst dominates
at rest-frame wavelengths >50 microns, with star formation rates >500 solar
masses per year. The trend of increasing AGN fraction with increasing IR
luminosity seen in IRAS galaxies peaks in HLIRGs, and is not higher than the
fraction seen in bright ULIRGs. The AGN and starburst luminosities correlate,
suggesting that a common physical factor, plausibly the dust masses, governs
their luminosities. Our results suggest that the HLIRG population is comprised
both of ULIRG-like galaxy mergers, and of young galaxies going through their
maximal star formation periods whilst harbouring an AGN. The coeval AGN and
starburst activity in our sources implies that starburst and AGN activity, and
the peak starburst and AGN luminosities, can be coeval in active galaxies
generally. When extrapolated to high-z our sources have comparable sub-mm
fluxes to sub-mm survey sources. At least some sub-mm survey sources are
therefore likely to be comprised of similar galaxy populations to those found
in the HLIRG population. It is also plausible from these results that high-z
sub-mm sources harbour heavily obscured AGN. The differences in X-ray and
sub-mm properties between HLIRGs at z~1 and sub-mm sources at z~3 implies
evolution between the two epochs. Either the mean AGN obscuration level is
greater at z~3 than at z~1, or the fraction of IR-luminous sources at z~3 that
contain AGN is smaller than that at z~1.Comment: 15 pages. Accepted for publication in MNRA
Efficient absolute aspect determination of a balloon borne far infrared telescope using a solid state optical photometer
The observational and operational efficiency of the TIFR 1 meter balloon
borne far infrared telescope has been improved by incorporating a multielement
solid state optical photometer (SSOP) at the Cassegrain focus of the telescope.
The SSOP is based on a 1-D linear photo diode array (PDA). The online and
offline processing schemes of the PDA signals which have been developed, lead
to improvement in the determination of absolute telescope aspect (
0\farcm8), which is very crucial for carrying out the observations as well as
offline analysis. The SSOP and its performance during a recent balloon flight
are presented here.Comment: To appear in the February 2000 issue of the PAS
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