313 research outputs found
A Deep Search For Faint Galaxies Associated With Very Low-redshift C IV Absorbers: III. The Mass- and Environment-dependent Circumgalactic Medium
Using Hubble Space Telescope Cosmic Origins Spectrograph observations of 89
QSO sightlines through the Sloan Digital Sky Survey footprint, we study the
relationships between C IV absorption systems and the properties of nearby
galaxies as well as large-scale environment. To maintain sensitivity to very
faint galaxies, we restrict our sample to 0.0015 < z < 0.015, which defines a
complete galaxy survey to L > 0.01 L* or stellar mass log M_* > 8 Msun. We
report two principal findings. First, for galaxies with impact parameter rho <
1 rvir, C IV detection strongly depends on the luminosity/stellar mass of the
nearby galaxy. C IV is preferentially associated with galaxies with log M_* >
9.5 Msun; lower mass galaxies rarely exhibit significant C IV absorption
(covering fraction f = 9 +12-6% for 11 galaxies with log M_* < 9.5 Msun).
Second, C IV detection within the log M_* > 9.5 Msun population depends on
environment. Using a fixed-aperture environmental density metric for galaxies
with rho < 160 kpc at z < 0.055, we find that 57+/-12% (8/14) of galaxies in
low-density regions (regions with fewer than seven L > 0.15 L* galaxies within
1.5 Mpc) have affiliated C IV absorption; however, none (0/7) of the galaxies
in denser regions show C IV. Similarly, the C IV detection rate is lower for
galaxies residing in groups with dark-matter halo masses of log Mhalo > 12.5
Msun. In contrast to C IV, H I is pervasive in the CGM without regard to mass
or environment. These results indicate that C IV absorbers with log N(C IV) >
13.5 cm^-2 trace the halos of log M_* > 9.5 Msun galaxies but also reflect
larger scale environmental conditions.Comment: 26 pages, 13 figures. ApJ, in pres
Leptonic decay of Heavy-light Mesons in a QCD Potential Model
We study the masses and decay constants of heavy-light flavour mesons D, Ds,
B and Bs in a QCD Potential model. The mesonic wavefunction is used to compute
the masses of D and B mesons in the ground state and the wavefunction is
transformed to momentum space to estimate the pseudoscalar decay constants of
these mesons. The leptonic decay widths and branching ratio of these mesons for
different leptonic channels are also computed to compare with the experimental
values. The results are found to be compatible with available data.Comment: 9 pages,3 table
Micropropagation of Curcuma amada (Roxb.)
Rhizome explants of Curcuma amada (Roxb.) produced shoots and roots simultaneously when cultured in B6 medium containing NAA and BAP. This technique would be suitable for field propagation and conservation.
 
Micropropagation of Curcuma amada (Roxb.)
Rhizome explants of Curcuma amada (Roxb.) produced shoots and roots simultaneously when cultured in B6 medium containing NAA and BAP. This technique would be suitable for field propagation and conservation.
 
Ornamental fisheries in Northeast India: State of the art and future directions
Not AvailableOrnamental fish keeping is a growing sector in aquaculture and still the 2nd most popular hobby comprising of 100 million of hobbyist in the world. More than 2500 fish species are involved in the global ornamental fish industry, where over 60% are of freshwater origin and 40% of marine origin. Out of the 422 fish species that have been reported for the Northeast region, 250 have the potential to be ornamental, with Assam having the largest number of ornamental fish species (187 species) recorded. Several species of fish can be considered as potential ornamental fish, at least during their early juvenile phase or during their breeding season. Wetlands/lakes of Assam and other Northeast states contribute a major portion in Ornamental fish diversity of Northeast India.Not Availabl
The COS Absorption Survey of Baryon Harbors (CASBaH): Warm-hot Circumgalactic Gas Reservoirs Traced by Ne VIII Absorption
We survey the highly ionized circumgalactic media (CGM) of 29 blindly
selected galaxies at 0.49 < z_(gal) < 1.44 based on high-S/N ultraviolet
spectra of z > 1 QSOs and the galaxy database from the COS Absorption Survey of
Baryon Harbors (CASBaH). We detect the Ne VIII doublet in nine of the galaxies,
and for gas with N(Ne VIII) > 10^13.3 cm^-2 (> 10^13.5 cm^-2), we derive a Ne
VIII covering fraction f_c = 75 +15/-25% (44 +22/-20%) within impact parameter
(rho) < 200 kpc of M_* = 10^(9.5-11.5) Msol galaxies and f_c = 70 +16/-22% (f_c
= 42 +20/-17%) within rho < 1.5 virial radii. We estimate the mass in Ne
VIII-traced gas to be M_gas(Ne VIII) > 10^9.5 Msol (Z/Zsol)^-1, or 6-20% of the
expected baryonic mass if the Ne VIII absorbers have solar metallicity.
Ionizing Ne VII to Ne VIII requires 207 eV, and photons with this energy are
scarce in the CGM. However, for the median halo mass and redshift of our
sample, the virial temperature is close to the peak temperature for the Ne VIII
ion, and the Ne VIII-bearing gas is plausibly collisionally ionized near this
temperature. Moreover, we find that photoionized Ne VIII requires cool and
low-density clouds that would be highly underpressured (by approximately two
orders of magnitude) relative to the putative, ambient virialized medium,
complicating scenarios where such clouds could survive. Thus, more complex
(e.g., non-equilibrium) models may be required; this first statistical sample
of Ne VIII absorber/galaxy systems will provide stringent constraints for
future CGM studies.Comment: Published in ApJL, Volume 877, Issue 2, Article L2
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