6,994 research outputs found
Lower limit on the entropy of black holes as inferred from gravitational wave observations
Black hole (BH) thermodynamics was established by Bekenstein and Hawking, who
made abstract theoretical arguments about the second law of thermodynamics and
quantum theory in curved spacetime respectively. Testing these ideas
experimentally has, so far, been impractical because the putative flux of
Hawking radiation from astrophysical BHs is too small to be distinguished from
the rest of the hot environment. Here, it is proposed that the spectrum of
emitted gravitational waves (GWs) after the merger of two BHs, in particular
the spectrum of GW150914, can be used to infer a lower limit on the magnitude
of the entropy of the post-merger BH. This lower bound is potentially
significant as it could be of the same order as the Bekenstein-Hawking entropy.
To infer this limit, we first assume that the result of the merger is an
ultracompact object with an external geometry which is Schwarzschild or Kerr,
but with an outer surface which is capable of reflecting in-falling GWs rather
than fully absorbing them. If the absence of deviations from the predictions of
general relativity in detected GW signals will be verified, we will then obtain
a bound on the minimal redshift factor of GWs that emerge from the vicinity of
the object's surface. This lack of deviations would also mean that the remnant
of the merger has to have a strongly absorbing surface and must then be a BH
for all practical purposes. We conclude that a relationship between the minimal
redshift factor and the BH entropy, which was first proposed by 't Hooft, could
then be used to set a lower bound on the entropy of the post-merger BH.Comment: Corrected error in estimation of current bounds on the entropy.
Improved discussion of energy stored in echoes, V3 replaced to match
published version, clarifications and explanations adde
Effect of Irrigation and Potash Levels on Keeping Quality of Potato
Irrigation and fertilizer are the most dominating factors, in deciding the keeping quality of potato. It is, therefore, essential to formulate the efficient, reliable and economically viable irrigation management strategy with the use of potassium nutrient in order to produce better keeping quality. The investigation comprising four levels of irrigation (25, 30, 35 and 40 mm CPE (Cumulative pan evaporation) and four levels of potash (0, 100, 125 and 150 kg/ha) was carried out at Research Farm of the Department of Vegetable Science, CCS Haryana Agricultural University, (Haryana) Hisar, India during two years to find out the optimum level of irrigation and potash for obtaining higher yield of potatoes with better keeping quality at ambient room temperature. The potato variety used for the investigation was Kufri Bahar. The treatments were laid out in a split plot design with three replications. The increasing levels of irrigation and potash showed significant improvement in keeping quality parameters of potato. Likewise, the values for physiological loss in weight and decay loss of potato tubers (%) at 15, 30, 45 and 60 days after harvest were the lowest with irrigation level 40 mm CPE and application of potash @ 150 kg/ha. The two years results suggest that the irrigation level 40 mm CPE along with potash @ 150 kg/ha has shown the best treatment combination for the storage of potato at ambient room temperature under semiarid conditions of Hisar (Haryana)
Standard Coupling Unification in SO(10), Hybrid Seesaw Neutrino Mass and Leptogenesis, Dark Matter, and Proton Lifetime Predictions
We discuss gauge coupling unification of the SM descending directly from
SO(10) while providing solutions to the three outstanding problems: neutrino
masses, dark matter, and the baryon asymmetry of the universe. Conservation of
matter parity as gauged discrete symmetry in the model calls for high-scale
spontaneous symmetry breaking through Higgs representation. This
naturally leads to the hybrid seesaw formula for neutrino masses mediated by
heavy scalar triplet and right-handed neutrinos. The seesaw formula predicts
two distinct patterns of RH masses, one hierarchical and another not so
hierarchical (or compact) when fitted with the neutrino oscillation data.
Predictions of the baryon asymmetry via leptogenesis are investigated through
the decays of both the patterns of RH masses. A complete flavor analysis
has been carried out to compute CP-asymmetries and solutions to Boltzmann
equations have been utilized to predict the baryon asymmetry. The additional
contribution to vertex correction mediated by the heavy left-handed triplet
scalar is noted to contribute as dominantly as other Feynman diagrams. We have
found successful predictions of the baryon asymmetry for both the patterns of
RH masses. The triplet fermionic dark matter at the TeV scale carrying
even matter parity is naturally embedded into the non-standard fermionic
representation of SO(10). In addition to the triplet scalar and the
triplet fermion, the model needs a nonstandard color octet fermion of mass
GeV to achieve precision gauge coupling unification. Threshold
corrections due to superheavy components of and other representations
are estimated and found to be substantial. It is noted that the proton life
time predicted by the model is accessible to the ongoing and planned
experiments over a wide range of parameter space.Comment: 58 pages PDFLATEX, 19 Figures, Revised as suggested by JHEP Revie
Long-term record of aerosol optical properties and chemical composition from a high-altitude site (Manora Peak) in Central Himalaya
A long-term study, conducted from February 2005 to July 2008, involving chemical composition and optical properties of ambient aerosols from a high-altitude site (Manora Peak: 29.4°N, 79.5°E, ~1950ma.s.l.) in the central Himalaya is reported here. The total suspended particulate (TSP) mass concentration varied from 13 to 272 µgm.3 over a span of 42 months. Aerosol optical depth (AOD) and TSP increase significantly during the summer (April-June) due to increase in the concentration of mineral dust associated with the long-range transport from desert regions (from the middle-East and Thar Desert in western India). The seasonal variability in the carbonaceous species (EC, OC) is also significantly pronounced, with lower concentrations during the summer and monsoon (July-August) and relatively high during the post-monsoon (September-November) and winter (December-March). On average, total carbonaceous aerosols (TCA) and water-soluble inorganic species (WSIS) contribute nearly 25 and 10% of the TSP mass, respectively. The WSOC/OC ratios range from 0.36 to 0.83 (average: 0.55±0.15), compared to lower ratios in the Indo-Gangetic Plain (range: 0.35-0.40), and provide evidence for the enhanced contribution from secondary organic aerosols. The mass fraction of absorbing EC ranged from less than a percent (during the summer) to as high as 7.6% (during the winter) and absorption coefficient (babs, at 678 nm) varied between 0.9 to 33.9Mm-1 (1Mm-1=10-6 m-1). A significant linear relationship between babs and EC (µgCm-3) yields a slope of 12.2 (±2.3) m2 g-1, which is used as a measure of the mass absorption efficiency (σabs) of EC
Record size black marlin, Makaira indica (Cuvier, 1832) landed at Bhimilipatnam, Andhra Pradesh
A gigantic black marlin, Makaira indica measuring
4.3 m in length and weighing around 450 kg was
landed at Bhimilipatnam beach landing centre and
brought to Visakhapatnam Fishing Harbour
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