6,826 research outputs found
Flat Symplectic Bundles of N-Extended Supergravities, Central Charges and Black-Hole Entropy
In these lectures we give a geometrical formulation of N-extended
supergravities which generalizes N=2 special geometry of N=2 theories. In all
these theories duality symmetries are related to the notion of "flat symplectic
bundles" and central charges may be defined as "sections" over these bundles.
Attractor points giving rise to "fixed scalars" of the horizon geometry and
Bekenstein-Hawking entropy formula for extremal black-holes are discussed in
some details.Comment: Based on lectures given by S. Ferrara at the 5th Winter School on
Mathematical Physics held at the Asia Pacific Center for Theoretical Physics,
Seul (Korea), February 199
Galaxies into the Dark Ages
We consider the capabilities of current and future large facilities operating
at 2\,mm to 3\,mm wavelength to detect and image the [CII] 158\,m line
from galaxies into the cosmic "dark ages" ( to 20). The [CII] line
may prove to be a powerful tool in determining spectroscopic redshifts, and
galaxy dynamics, for the first galaxies. We emphasize that the nature, and even
existence, of such extreme redshift galaxies, remains at the frontier of open
questions in galaxy formation. In 40\,hr, ALMA has the sensitivity to detect
the integrated [CII] line emission from a moderate metallicity, active
star-forming galaxy [; star formation rate (SFR) =
5\,\,yr], at at a significance of 6. The
next-generation Very Large Array (ngVLA) will detect the integrated [CII] line
emission from a Milky-Way like star formation rate galaxy (, SFR = 1\,\,yr), at at a significance
of 6. Imaging simulations show that the ngVLA can determine rotation
dynamics for active star-forming galaxies at , if they exist. Based
on our very limited knowledge of the extreme redshift Universe, we calculate
the count rate in blind, volumetric surveys for [CII] emission at
to 20. The detection rates in blind surveys will be slow (of order unity per
40\,hr pointing). However, the observations are well suited to commensal
searches. We compare [CII] with the [OIII] 88m line, and other ancillary
information in high galaxies that would aid these studies.Comment: 11pages, 8 figures, Accepted for the Astrophysical Journa
F^4 Terms in N=4 String Vacua
We discuss terms in torroidal compactifications of type-I and
heterotic SO(32) string theory. We give a simple argument why only short BPS
multiplets contribute to these terms at one loop, and verify heterotic-type-I
duality to this order.Comment: 10 pages, Latex. A statement about superinvariants was corrected.
Minor cosmetic changes were also made. To appear in Proceedings of Trieste
Spring School and Workshop, April 199
Multiplet Structures of BPS Solitons
There exist simple single-charge and multi-charge BPS p-brane solutions in
the D-dimensional maximal supergravities. From these, one can fill out orbits
in the charge vector space by acting with the global symmetry groups. We give a
classification of these orbits, and the associated cosets that parameterise
them.Comment: Latex, 34 pages, comments and reference adde
CO line emission from galaxies in the Epoch of Reionization
We study the CO line luminosity (), the shape of the CO Spectral
Line Energy Distribution (SLED), and the value of the CO-to-
conversion factor in galaxies in the Epoch of Reionization (EoR). To this aim,
we construct a model that simultaneously takes into account the radiative
transfer and the clumpy structure of giant molecular clouds (GMCs) where the CO
lines are excited. We then use it to post-process state-of-the-art zoomed, high
resolution (), cosmological simulation of a main-sequence
(, ) galaxy, "Alth{\ae}a", at . We find that the CO emission
traces the inner molecular disk () of Alth{\ae}a with
the peak of the CO surface brightness co-located with that of the [CII] 158 emission. Its is comparable
to that observed in local galaxies with similar stellar mass. The high
() gas surface density in
Alth{\ae}a, its large Mach number (\mach), and the warm kinetic
temperature () of GMCs yield a CO SLED peaked at the
CO(7-6) transition, i.e. at relatively high-, and a CO-to-
conversion factor lower than that of the Milky Way. The ALMA observing time
required to detect (resolve) at 5 the CO(7-6) line from galaxies
similar to Alth{\ae}a is h ( h).Comment: 16 pages, 14 figures, accepted for publication in MNRA
Very extended cold gas, star formation and outflows in the halo of a bright QSO at z>6
Past observations of QSO host galaxies at z >6 have found cold gas and star
formation on compact scales of a few kiloparsecs. We present new high
sensitivity IRAM PdBI follow-up observations of the [CII] 158micron emission
line and FIR continuum in the host galaxy of SDSS J1148+5152, a luminous QSO at
redshift 6.4189. We find that a large fraction of the gas traced by [CII] is at
high velocities, up to ~1400 km/s relative to the systemic velocity, confirming
the presence of a major quasar-driven outflow indicated by previous
observations. The outflow has a complex morphology and reaches a maximum
projected radius of ~30 kpc. The extreme spatial extent of the outflow allows
us, for the first time in an external galaxy, to estimate mass-loss rate,
kinetic power and momentum rate of the outflow as a function of the projected
distance from the nucleus and the dynamical time-scale. These trends reveal
multiple outflow events during the past 100 Myr, although the bulk of the mass,
energy and momentum appear to have been released more recently, within the past
~20 Myr. Surprisingly, we discover that also the quiescent gas at systemic
velocity is extremely extended. More specifically, we find that, while 30% of
the [CII] within v\in(-200, 200) km/s traces a compact component that is not
resolved by our observations, 70% of the [CII] emission in this velocity range
is extended, with a projected FWHM size of 17.4+-1.4 kpc. We detect FIR
continuum emission associated with both the compact and the extended [CII]
components, although the extended FIR emission has a FWHM of 11+-3 kpc, thus
smaller than the extended [CII] source. Overall, our results indicate that the
cold gas traced by [CII] is distributed up to r~30 kpc. A large fraction of
extended [CII] is likely associated with star formation on large scales, but
the [CII] source extends well beyond the FIR continuum.Comment: Accepted for publication in A&A, 21 pages, 18 figures, 3 tables (v2:
accepted version, discussion expanded in Sect. 3, 4 and in the Appendices,
minor changes elsewhere
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