4,962 research outputs found
Reply to "Comment on 'Gravitating Magnetic Monopole in the Global Monopole Spacetime' "
In this Reply I present some arguments in favor of the stability of the
topological defect composed by global and magnetic monopoles.Comment: 1 page, no figures. Revised version improves the theoretical analysis
about electrostatic self-interaction in the global monopole spacetim
Vacuum Polarization for a Massless Spin-1/2 Field in the Global Monopole Spacetime at Nonzero Temperature
In this paper we present the effects produced by the temperature in the
renormalized vacuum expectation value of the zero-zero component of the
energy-momentum tensor associated with massless left-handed spinor field in the
pointlike global monopole spacetime. In order to develop this calculation we
had to obtain the Euclidean thermal Green function in this background. Because
the expression obtained for the thermal energy density cannot be expressed in a
closed form, its explicit dependence on the temperature is not completely
evident. So, in order to obtain concrete information about its thermal
behavior, we develop a numerical analysis of our result in the high-temperature
limit for specific values of the parameter which codify the presence
of the monopole.Comment: 22 pages, LaTex format, 5 figure
Electrostatic self-force in (2+1)-dimensional cosmological gravity
Point sources in (2+1)-dimensional gravity are conical singularities that
modify the global curvature of the space giving rise to self-interaction
effects on classical fields. In this work we study the electrostatic
self-interaction of a point charge in the presence of point masses in
(2+1)-dimensional gravity with a cosmological constant.Comment: 9 pages, Late
Star formation in low density HI gas around the Elliptical Galaxy NGC2865
Interacting galaxies surrounded by HI tidal debris are ideal sites for the
study of young clusters and tidal galaxy formation. The process that triggers
star formation in the low-density environments outside galaxies is still an
open question. New clusters and galaxies of tidal origin are expected to have
high metallicities for their luminosities. Spectroscopy of such objects is,
however, at the limit of what can be done with existing 8-10m class telescopes,
which has prevented statistical studies of these objects. NGC2865 is an
UV-bright merging elliptical galaxy with shells and extended HI tails. The
regions observed in this work were previously detected using multi-slit imaging
spectroscopy. We obtain new multislit spectroscopy of six young star-forming
regions around NGC2865, to determine their redshifts and metallicities. The six
emission-line regions are located 16-40 kpc from NGC2865 and they have similar
redshifts. They have ages of ~10Myears and an average metallicity of
12+log(O/H) ~ 8.6, suggesting a tidal origin for the regions. It is noted that
they coincide with an extended HI tail, which has projected density of N
< 10 cm, and displays a low surface brightness counterpart. These
regions may represent the youngest of the three populations of star clusters
already identified in NGC2865. The high, nearly-solar, oxygen abundances found
for the six regions in the vicinity of NGC2865 suggest that they were formed by
pre-enriched material from the parent galaxy, from gas removed during the last
major merger. Given the mass and the location of the HII regions, we can
speculate that these young star-forming regions are potential precursors of
globular clusters that will be part of the halo of NGC2865 in the future. Our
result supports the use of the multi-slit imaging spectroscopy as a useful tool
for finding nearly-formed stellar systems around galaxies.Comment: 7 pages, 2 figures accepted in A&
AdS_4/CFT_3 Construction from Collective Fields
We pursue the construction of higher-spin theory in AdS_4 from CFT_3 of the
O(N) vector model in terms of canonical collective fields. In null plane
quantization an exact map is established between the two spaces. The
coordinates of the AdS_4 space-time are generated from the collective
coordinates of the bi-local field. This, in the light cone gauge, provides an
exact one to one reconstruction of bulk AdS_4 space-time and higher-spin
fields.Comment: 17 pages, no figures; v2: references added; v3: minor change
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