4,948 research outputs found
The stellar mass-halo mass relation of isolated field dwarfs: a critical test of CDM at the edge of galaxy formation
We fit the rotation curves of isolated dwarf galaxies to directly measure the
stellar mass-halo mass relation () over the mass range . By accounting for cusp-core
transformations due to stellar feedback, we find a monotonic relation with
little scatter. Such monotonicity implies that abundance matching should yield
a similar if the cosmological model is correct. Using the 'field
galaxy' stellar mass function from the Sloan Digital Sky Survey (SDSS) and the
halo mass function from the Cold Dark Matter Bolshoi simulation, we
find remarkable agreement between the two. This holds down to M, and to M if we
assume a power law extrapolation of the SDSS stellar mass function below M.
However, if instead of SDSS we use the stellar mass function of nearby galaxy
groups, then the agreement is poor. This occurs because the group stellar mass
function is shallower than that of the field below M,
recovering the familiar 'missing satellites' and 'too big to fail' problems.
Our result demonstrates that both problems are confined to group environments
and must, therefore, owe to 'galaxy formation physics' rather than exotic
cosmology.
Finally, we repeat our analysis for a Warm Dark Matter cosmology,
finding that it fails at 68% confidence for a thermal relic mass of keV, and keV if we use the power law extrapolation
of SDSS. We conclude by making a number of predictions for future surveys based
on these results.Comment: 22 pages; 2 Tables; 10 Figures. This is the version accepted for
publication in MNRAS. Key changes: (i) added substantially more information
on the surveys used to measure the stellar mass functions; (ii) added tests
of the robustness of our results. Results and conclusions unchanged from
previously. Minor typos corrected from previous versio
Expectations for first single-top studies in CMS proton-proton collisions
We report on the expectations for first single top studies at the LHC with the CMS experiment. The Standard Model predicts the production of single top quark through three electroweak processes at LHC, referred to as t, s and tW
channels. The t-channel has the highest cross section and the most potential for early observation. We describe the search strategy for the t-channel applied on a Monte Carlo sample at 10TeV p-p collision energy with an integrated luminosity of 200 pbâ1 and on the expectations for the search of single top t-channel in the 7TeV scenario
The search for the single top at the LHC
We report on the predictions of the Standard Model for the single top-quark production at LHC and on the analysis strategies adopted by CMS and ATLAS for the single top-quark search. The Standard Model predicts the production
of single top quark through three electroweak processes in the LHC energy reach, referred to as t, s and tW channels, resulting in distinct topologies and backgrounds. Different analysis strategies to search for the single top have been developed by CMS and ATLAS experiments. For the 14TeV center-of-mass energy scenario all the channels have been considered, while for the 10TeV scenario a specific strategy
has been developed only for the t-channel and has been applied on Monte Carlo samples assuming an integrated luminosity of 200 pbâ1
Multiple abnormalities in the skull of a prostitute. An autopsy report (1900)
OBJECTIVE: The study presents and comments on the publication of an autopsy report. CASE REPORT: In 1900 De Blasio published an article entitled "Multiple abnormalities in a prostitute's skull" in the "Journal of Psychiatry, Criminal Anthropology and related sciences". In this work De Blasio related anomalies at the cranial level to the presence of mental pathologies. The skull belonged to a 24-year-old prostitute who died of syphilitic hepatitis. In his article, De Blasio described the life of the woman, after which he gave a macroscopic description of the skull. De Blasio believed that the subject's amoral behavior was caused by the anomalous shape of the subject's skull. CONCLUSION: From the study, it is evident that the school of criminal anthropology influenced De Blasio's autopsy medical practice, and it is interesting to note the interpretation of anthropologists of the time who tried to describe the link between physical and behavioral anomalies
The Pioneer anomaly and the holographic scenario
In this paper we discuss the recently obtained relation between the
Verlinde's holographic model and the first phenomenological Modified Newtonian
dynamics. This gives also a promising possible explanation to the Pioneer
anomaly.Comment: 5 pages, Accepted for publication in Astrophysics & Space Scienc
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
Gravitomagnetism and Relative Observer Clock Effects
The gravitomagnetic clock effect and the Sagnac effect for circularly
rotating orbits in stationary axisymmetric spacetimes are studied from a
relative observer point of view, clarifying their relationships and the roles
played by special observer families. In particular Semer\'ak's recent
characterization of extremely accelerated observers in terms of the two-clock
clock effect is shown to be complemented by a similarly special property of the
single-clock clock effect.Comment: 19 pages, LaTeX, IOP macros with package epsf and 1 eps figure, to
appear in Classical and Quantum Gravity, slight revisio
Angular momentum effects in weak gravitational fields
It is shown that, contrary to what is normally expected, it is possible to
have angular momentum effects on the geometry of space time at the laboratory
scale, much bigger than the purely Newtonian effects. This is due to the fact
that the ratio between the angular momentum of a body and its mass, expressed
as a length, is easily greater than the mass itself, again expressed as a
length.Comment: LATEX, 8 page
Noncommutativity and Lorentz Violation in Relativistic Heavy Ion Collisions
The experimental detection of the effects of noncommuting coordinates in
electrodynamic phenomena depends on the magnitude of |\theta B|, where \theta
is the noncommutativity parameter and B a background magnetic field. With the
present upper bound on \theta, given by \theta_{\rm bound} \simeq 1/(10 {\rm
TeV})^2, there was no large enough magnetic field in nature, including those
observed in magnetars, that could give visible effects or, conversely, that
could be used to further improve \theta_{\rm bound}. On the other hand,
recently it has been proposed that intense enough magnetic fields should be
produced at the beginning of relativistic heavy ion collisions. We discuss here
lepton pair production by free photons as one kind of signature of
noncommutativity and Lorentz violation that could occur at RHIC or LHC. This
allows us to obtain a more stringent bound on \theta, given by 10^{-3}
\theta_{\rm bound}, if such "exotic" events do not occur.Comment: Five pages, no figures
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