144 research outputs found
Signatures of accretion events in the halos of early-type galaxies from comparing PNe and GCs kinematics
We have compared the halo kinematics traced by globular clusters (GCs) and
planetary nebulae (PNe) for two elliptical galaxies in the Fornax and Virgo
clusters NGC 1399 and NGC 4649, and for the merger remnant NGC 5128 (Centaurus
A). We find differences in the rotational properties of the PN, red GC, and
blue GC systems in all these three galaxies. NGC 1399 PNe and GCs show line of
sight velocity distributions in specific regions that are significantly
different, based on Kolmogorov-Smirnov tests. The PN system shows multi-spin
components, with nearly opposite direction of rotation in the inner and the
outer parts. The GCs velocity field is not point-symmetric in the outer regions
of the galaxy, indicating that the system has not reached dynamical equilibrium
yet. In NGC 4649 PNe, red and blue GCs have different rotation axes and
rotational velocities. Finally, in NGC 5128 both PNe and GCs deviate from
equilibrium in the outer regions of the galaxy, and in the inner regions the PN
system is rotationally supported, whereas the GC system is dominated by
velocity dispersion. The observed different kinematic properties, including
deviations from point-symmetry, between PNe and GCs suggest that these systems
are accreted at different times by the host galaxy, and the most recent
accretion took place only few Gyr ago.We discuss two scenarios which may
explain some of these differences: i) tidal stripping of loosely-bound GCs, and
ii) multiple accretion of low luminosity and dwarf galaxies. Because these two
mechanisms affect mostly the GC system, differences with the PNe kinematics can
be expected.Comment: 14 pages, 13 figures, Accepted for publication in MNRAS. This new
version contains an improved analysis, which includes the study of
point-symmetry in the velocity fields and its implications for dynamical
equilibriu
Planetary nebula kinematics in NGC 1316: a young Sombrero
Aims. We present positions and velocities for 796 planetary nebulae (PNe) in
the Fornax Brightest Cluster Galaxy NGC 1316 (Fornax A). The planetary nebulae
and existing kinematics are used to explore the rotation of this merger remnant
and constrain dynamical models. Methods. Using FORS2 on the VLT, the PN
velocities were measured using a counter-dispersed slitless-spectroscopy
technique that produced the largest-to-date sample outside of the Local Group.
Spherical, non-rotating, constant-anisotropy Jeans models were con- strained by
observations of the planetary nebulae and existing integrated light spectra.
Results. The two-dimensional velocity field indicates dynamically-important
rotation that rises in the outer parts, possibly due to the outward transfer of
angular momentum during the merger. The modeling indicates a high dark matter
content, particularly in the outer parts, that is consistent with previous
estimates from dynamical models, lensing and stellar population models.
Conclusions. The exceptionally large sample of PN velocities makes it possible
to explore the kinematics of NGC 1316 in detail. Comparing the results to other
early-type galaxies like NGC 1399 and NGC 4594 (M104, Sombrero), NGC 1316
represents a transi- tion phase from a major-merger event to a bulge-dominated
galaxy like NGC 4594
Interplay between unconventional superconductivity and heavy-fermion quantum criticality: CeCuSi versus YbRhSi
In this paper the low-temperature properties of two isostructural canonical
heavy-fermion compounds are contrasted with regards to the interplay between
antiferromagnetic (AF) quantum criticality and superconductivity. For
CeCuSi, fully-gapped d-wave superconductivity forms in the vicinity of
an itinerant three-dimensional heavy-fermion spin-density-wave (SDW) quantum
critical point (QCP). Inelastic neutron scattering results highlight that both
quantum critical SDW fluctuations as well as Mott-type fluctuations of local
magnetic moments contribute to the formation of Cooper pairs in CeCuSi.
In YbRhSi, superconductivity appears to be suppressed at
mK by AF order ( = 70 mK). Ultra-low temperature measurements reveal a
hybrid order between nuclear and 4f-electronic spins, which is dominated by the
Yb-derived nuclear spins, to develop at slightly above 2 mK. The hybrid
order turns out to strongly compete with the primary 4f-electronic order and to
push the material towards its QCP. Apparently, this paves the way for
heavy-fermion superconductivity to form at = 2 mK. Like the pressure -
induced QCP in CeRhIn, the magnetic field - induced one in YbRhSi
is of the local Kondo-destroying variety which corresponds to a Mott-type
transition at zero temperature. Therefore, these materials form the link
between the large family of about fifty low- unconventional heavy - fermion
superconductors and other families of unconventional superconductors with
higher s, notably the doped Mott insulators of the cuprates, organic
charge-transfer salts and some of the Fe-based superconductors. Our study
suggests that heavy-fermion superconductivity near an AF QCP is a robust
phenomenon.Comment: 30 pages, 7 Figures, Accepted for publication in Philosophical
Magazin
Diffuse light and galaxy interactions in the core of nearby clusters
The kinematics of the diffuse light in the densest regions of the nearby
clusters can be unmasked using the planetary nebulae (PNs) as probes of the
stellar motions. The position-velocity diagrams around the brightest cluster
galaxies (BCGs) identify the relative contributions from the outer halos and
the intracluster light (ICL), defined as the light radiated by the stars
floating in the cluster potential. The kinematics of the ICL can then be used
to asses the dynamical status of the nearby cluster cores and to infer their
formation histories. The cores of the Virgo and Coma are observed to be far
from equilibrium, with mergers currently on-going, while the ICL properties in
the Fornax and Hydra clusters show the presence of sub-components being
accreted in their cores, but superposed to an otherwise relaxed population of
stars. Finally the comparison of the observed ICL properties with those
predicted from Lambda-CDM simulations indicates a qualitative agreement and
provides insights on the ICL formation. Both observations and simulations
indicate that BCG halos and ICL are physically distinct components, with the
``hotter" ICL dominating at large radial distances from the BCGs halos as the
latter become progressively fainter.Comment: 14 pages, 5 figures. Invited review to appear in the proceedings of
"Galaxies and their masks" eds. Block, D.L., Freeman, K.C. and Puerari, I.,
2010, Springer (New York
Low Temperature Properties of Anisotropic Superconductors with Kondo Impurities
We present a self-consistent theory of superconductors in the presence of
Kondo impurities, using large- slave-boson methods to treat the impurity
dynamics. The technique is tested on the s-wave case and shown to give good
results compared to other methods for . We calculate low temperature
thermodynamic and transport properties for various superconducting states,
including isotropic s-wave and representative anisotropic model states with
line and point nodes on the Fermi surface.Comment: 21 pages, RevTeX 3.0, 12 figures available upon request, UF preprin
The PN.S Elliptical Galaxy Survey: a standard LCDM halo around NGC 4374?
As part of our current programme to test LCDM predictions for dark matter
(DM) haloes using extended kinematical observations of early-type galaxies, we
present a dynamical analysis of the bright elliptical galaxy NGC 4374 (M84)
based on ~450 Planetary Nebulae (PNe) velocities from the PN.Spectrograph,
along with extended long-slit stellar kinematics. This is the first such
analysis of a galaxy from our survey with a radially constant velocity
dispersion profile. We find that the spatial and kinematical distributions of
the PNe agree with the field stars in the region of overlap. The velocity
kurtosis is consistent with zero at almost all radii. We construct a series of
Jeans models, fitting both velocity dispersion and kurtosis to help break the
mass-anisotropy degeneracy. Our mass models include DM halos either with
shallow cores or with central cusps as predicted by cosmological simulations -
along with the novel introduction in this context of adiabatic halo contraction
from baryon infall. Both classes of models confirm a very massive dark halo
around NGC 4374, demonstrating that PN kinematics data are well able to detect
such haloes when present. Considering the default cosmological mass model, we
confirm earlier suggestions that bright galaxies tend to have halo
concentrations higher than LCDM predictions, but this is found to be solved if
either a Salpeter IMF or adiabatic contraction with a Kroupa IMF is assumed.
Thus for the first time a case is found where the PN dynamics may well be
consistent with a standard dark matter halo. A cored halo can also fit the
data, and prefers a stellar mass consistent with a Salpeter IMF. The less
dramatic dark matter content found in lower-luminosity "ordinary" ellipticals
suggests a bimodality in the halo properties which may be produced by divergent
baryonic effects during their assembly histories.Comment: 22 pages, 14 figures. MNRAS, accepte
CAR-T cell. the long and winding road to solid tumors
Adoptive cell therapy of solid tumors with reprogrammed T cells can be considered the "next generation" of cancer hallmarks. CAR-T cells fail to be as effective as in liquid tumors for the inability to reach and survive in the microenvironment surrounding the neoplastic foci. The intricate net of cross-interactions occurring between tumor components, stromal and immune cells leads to an ineffective anergic status favoring the evasion from the host's defenses. Our goal is hereby to trace the road imposed by solid tumors to CAR-T cells, highlighting pitfalls and strategies to be developed and refined to possibly overcome these hurdles
The PN.S Elliptical Galaxy Survey: the dark matter in NGC 4494
We present new Planetary Nebula Spectrograph observations of the ordinary
elliptical galaxy NGC 4494, resulting in positions and velocities of 255 PNe
out to 7 effective radii (25 kpc). We also present new wide-field surface
photometry from MMT/Megacam, and long-slit stellar kinematics from VLT/FORS2.
The spatial and kinematical distributions of the PNe agree with the field stars
in the region of overlap. The mean rotation is relatively low, with a possible
kinematic axis twist outside 1 Re. The velocity dispersion profile declines
with radius, though not very steeply, down to ~70 km/s at the last data point.
We have constructed spherical dynamical models of the system, including Jeans
analyses with multi-component LCDM-motivated galaxies as well as logarithmic
potentials. These models include special attention to orbital anisotropy, which
we constrain using fourth-order velocity moments. Given several different sets
of modelling methods and assumptions, we find consistent results for the mass
profile within the radial range constrained by the data. Some dark matter (DM)
is required by the data; our best-fit solution has a radially anisotropic
stellar halo, a plausible stellar mass-to-light ratio, and a DM halo with an
unexpectedly low central density. We find that this result does not
substantially change with a flattened axisymmetric model.
Taken together with other results for galaxy halo masses, we find suggestions
for a puzzling pattern wherein most intermediate-luminosity galaxies have very
low concentration halos, while some high-mass ellipticals have very high
concentrations. We discuss some possible implications of these results for DM
and galaxy formation.Comment: 29 pages, 17 figures. MNRAS, accepte
The Globular Cluster Systems of Abell 1185
We examine the properties of a previously discovered population of globular
clusters in the heart of the rich galaxy cluster Abell 1185 that might be
intergalactic in nature. Deep images obtained with the Advanced Camera for
Surveys (ACS) aboard Hubble Space Telescope (HST) confirm the presence of ~
1300 globular clusters brighter than I_{F814W} = 27.3 mag in a field devoid of
any large galaxies. The luminosities and colors of these objects are found to
be similar to those of metal-poor globular clusters observed in many galaxies
to date. Although a significant fraction of the detected globular clusters
undoubtedly reside in the outer halos of galaxies adjacent to this field,
detailed modeling of their distribution suggests that the majority of these
objects are likely to be intergalactic, in the sense that they are not
gravitationally bound to any individual galaxy. We conclude that the true
nature and origin of the globular cluster population in the core of A1185 --
galactic residents or intergalactic wanderers -- remains uncertain, and suggest
how future observation could resolve this ambiguity.Comment: Accepted for publication in Astronomy and Astrophysics, 13 pages, 15
figure
Psychotropic drug influences on brain acetylcholine utilization
The cholinergic antisynthesis agent HC-3 was given intraventricularly to young male rats 20–30 days old to deplete brain acetylcholine (ACh). The rate of HC-3 induced depletion of ACh was used as an index of ACh utilization. Total brain ACh was determined following various doses of chlordiazepoxide, pentobarbital, chlorpromazine, methotrimeprazine, imipramine, morphine, d -amphetamine, scopolamine, LSD-25, and phencyclidine given i.p. alone and after intraventricular administration of HC-3. It was found that psychotropic drugs have marked differential effects on the rate of HC-3 induced ACh depletion.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46382/1/213_2004_Article_BF00421968.pd
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