23,248 research outputs found

### Far-infrared surveys of galaxy evolution

Roughly half of the radiation from evolving galaxies in the early universe
reaches us in the far-infrared and submillimeter wavelength range. Recent major
advances in observing capabilities, in particular the launch of the Herschel
Space Observatory in 2009, have dramatically enhanced our ability to use this
information in the context of multiwavelength studies of galaxy evolution. Near
its peak, three quarters of the cosmic infrared background is now resolved into
individually detected sources. The use of far-infrared diagnostics of
dust-obscured star formation and of interstellar medium conditions has expanded
from rare extreme high-redshift galaxies to more typical main sequence galaxies
and hosts of active galactic nuclei, out to z>~2. These studies shed light on
the evolving role of steady equilibrium processes and of brief starbursts, at
and since the peak of cosmic star formation and black hole accretion. This
review presents a selection of recent far-infrared studies of galaxy evolution,
with an emphasis on Herschel resultsComment: Review for Annual Review Astronomy Astrophysics vol. 52 (2014

### Globular cluster formation in merging galaxies?

The properties of a population of luminous blue clusters in the merging galaxy NGC 3597 are discussed, and the observability of the signature of such a population in later evolutionary stages of a merger is assessed. NGC 3597 is an advanced merger which has already developed into an elliptical-like object with a de Vaucouleurs brightness distribution, but intense star formation is continuing in the central 4 kpc. A population of unresolved blue objects that are concentrated towards the central region is identified as clusters belonging to NGC 3597

### Chiral SU(3) Symmetry and Strangeness

In this talk we review recent progress on the systematic evaluation of the
kaon and antikaon spectral functions in dense nuclear matter based on a chiral
SU(3) description of the low-energy pion-, kaon- and antikaon-nucleon
scattering data.Comment: 9 pages, 4 figures, invited talk given by M.F.M.L. at the SQM2001
conferenc

### Combined large-N_c and heavy-quark operator analysis for the chiral Lagrangian with charmed baryons

The chiral $SU(3)$ Lagrangian with charmed baryons of spin $J^P=1/2^+$ and
$J^P=3/2^+$ is analyzed. We consider all counter terms that are relevant at
next-to-next-to-next-to-leading order (N$^3$LO) in a chiral extrapolation of
the charmed baryon masses. At N$^2$LO we find 16 low-energy parameters. There
are 3 mass parameters for the anti-triplet and the two sextet baryons, 6
parameters describing the meson-baryon vertices and 7 symmetry breaking
parameters. The heavy-quark spin symmetry predicts four sum rules for the
meson-baryon vertices and degenerate masses for the two baryon sextet fields.
Here a large-$N_c$ operator analysis at NLO suggests the relevance of one
further spin-symmetry breaking parameter. Going from N$^2$LO to N$^3$LO adds 17
chiral symmetry breaking parameters and 24 symmetry preserving parameters. For
the leading symmetry conserving two-body counter terms involving two baryon
fields and two Goldstone boson fields we find 36 terms. While the heavy-quark
spin symmetry leads to $36-16=20$ sum rules, an expansion in $1/N_c$ at
next-to-leading order (NLO) generates $36-7= 29$ parameter relations. A
combined expansion leaves 3 unknown parameters only. For the symmetry breaking
counter terms we find 17 terms, for which there are $17-9=8$ sum rules from the
heavy-quark spin symmetry and $17-5=12$ sum rules from a $1/N_c$ expansion at
NLO.Comment: 34 pages - one table - corrections applie

### Ultra-Luminous Infrared Mergers: Elliptical Galaxies in Formation?

We report high quality near-infrared spectroscopy of 12 ultra-luminous
infrared galaxy mergers (ULIRGs). Our new VLT and Keck data provide ~0.5"
resolution, stellar and gas kinematics of these galaxies most of which are
compact systems in the last merger stages.
We confirm that ULIRG mergers are 'ellipticals-in-formation'. Random motions
dominate their stellar dynamics, but significant rotation is common. Gas and
stellar dynamics are decoupled in most systems. ULIRGs fall on or near the
fundamental plane of hot stellar systems, and especially on its less evolution
sensitive, r(eff)-sigma projection. The ULIRG velocity dispersion distribution,
their location in the fundamental plane and their distribution of
v(rot)*sin(i)/sigma closely resemble those of intermediate mass (~L*),
elliptical galaxies with moderate rotation. As a group ULIRGs do not resemble
giant ellipticals with large cores and little rotation. Our results are in good
agreement with other recent studies indicating that disky ellipticals with
compact cores or cusps can form through dissipative mergers of gas rich, disk
galaxies while giant ellipticals with large cores have a different formation
history.Comment: submitted to Ap

### Dimension Spectra of Lines

This paper investigates the algorithmic dimension spectra of lines in the
Euclidean plane. Given any line L with slope a and vertical intercept b, the
dimension spectrum sp(L) is the set of all effective Hausdorff dimensions of
individual points on L. We draw on Kolmogorov complexity and geometrical
arguments to show that if the effective Hausdorff dimension dim(a, b) is equal
to the effective packing dimension Dim(a, b), then sp(L) contains a unit
interval. We also show that, if the dimension dim(a, b) is at least one, then
sp(L) is infinite. Together with previous work, this implies that the dimension
spectrum of any line is infinite

### Analytical results for a Fokker-Planck equation in the small noise limit

We present analytical results for the lowest cumulants of a stochastic
process described by a Fokker-Planck equation with nonlinear drift. We show
that, in the limit of small fluctuations, the mean, the variance and the
covariance of the process can be expressed in compact form with the help of the
Lambert W function. As an application, we discuss the interplay of noise and
nonlinearity far from equilibrium.Comment: 5 pages, 4 figure

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