1,642 research outputs found
Localization of binary neutron star mergers with a single Cosmic Explorer
Next-generation ground-based gravitational-wave detectors, such as Cosmic
Explorer (CE), are expected to be sensitive to gravitational-wave signals with
frequencies as low as 5 Hz, allowing signals to spend a significant amount of
time in the detector frequency band. As a result, the effects caused by the
rotation of the Earth become increasingly important for such signals.
Additionally, the length of the arms of these detectors can be comparable to
the wavelength of detectable gravitational waves, which introduces
frequency-dependent effects that are not significant in current-generation
detectors. These effects are expected to improve the ability to localize
compact binary coalescences in the sky even when using only one detector. This
study aims to understand how much these effects can help in localization. We
present the first comprehensive Bayesian parameter estimation framework that
accounts for all these effects using \textsc{Bilby}, a commonly used Bayesian
parameter estimation tool. We focus on sky localization constraints for binary
neutron star events with an optimal signal-to-noise ratio of 1000 with one
detector at the projected CE sensitivity. We find that these effects help
localize sources using one detector with sky areas as low as 10 square degrees.
Moreover, we explore and discuss how ignoring these effects in the parameter
estimation can lead to biases in the inference.Comment: Version accepted by PR
Dark matter from primordial black holes would hold charge
We explore the possibility that primordial black holes (PBHs), formed early
in the history of the Universe, contain electric charge down to the present
day. We find that PBHs should hold a non-zero charge at their formation,
sourced by both Poisson fluctuations and collisions of charged particles in the
early universe. Although initial charges could be of either sign and are
thought to be subject to fast discharge processes, we show that dipolar
magnetic fields from rotating black holes can deviate them, avoiding their
accretion or emission to infinity, regardless of the PBH mass. Moreover, we
find that charged, maximally rotating PBHs produce magnetic fields able to
cancel the Schwinger effect for all masses, and the Hawking emission for PBHs
with M>1\,\mbox{kg}. These mechanisms could allow PBHs to maintain their
charge for extended periods. At late times, we conclude that the plasma within
virialised dark matter haloes can endow PBHs with a net average negative
charge. We report resulting charges Q/M \sim -10^{-32}\,C/\mbox{kg} and Q/M
\sim -10^{-22}\,C/\mbox{kg} for two current windows where PBHs can make up all
of the dark matter; being respectively M\sim 10^{20}\,\mbox{kg} and M\sim
10^{30}\,\mbox{kg}. The charge of PBHs in haloes lies below the Schwinger
limit for discharge, which would effectively make PBH dark matter slightly
non-neutral to the present day. Altogether, the initial PBH charge, possible
shielding against discharge, and late time negative charge accretion, show that
PBHs of all masses could hold a net charge, with values about two to ten orders
of magnitude lower than the maximal bound imposed by subextremal
Reissner-Nordstr\"om (RN) PBHs, and even the extremal charge for Planck mass
PBHs. The latter are of particular interest, as they could constitute charged
stable relics, composing the entirety of dark matter in the Universe.Comment: 24 pages, 6 figures, minor changes, matches the version submitted to
the journa
Variación espacio-temporal de la cobertura de coral del norte del Sistema Arrecifal Mesoamericano, Península de Yucatán, México
Evaluating the response of coral assemblages to different disturbances is important because variations in species composition may have consequences for ecosystem functioning due to their different functional roles in coral reefs. This study evaluates changes in diversity, structure and composition of coral assemblages of the coral reefs of two national parks in the northern sector of the Mesoamerican Barrier Reef System spanning the period from 2006 to 2012, just after the impact of two hurricanes in the area. Coral assemblages in the Cancún National Park included fewer species and lower live coral coverage ( < 15%) than those recorded in Cozumel. In the Cancún National Park, the species with the highest coral cover was Porites astreoides (more than 40% relative cover), and no significant temporal changes were observed in live coral cover and species composition. On the other hand, in the Cozumel National Park the dominant species were Agaricia agaricites, Siderastrea siderea and Porites astreoides, and the coral reefs showed an increase in live coral cover from 16% in 2006 to 29% in 2012. The dynamics of coral assemblages differed between the two parks: while there is an apparent stability in the current composition of the Cancún reefs, the Cozumel reefs show an increase in the abundance of the aforementioned dominant species. However, it is possible that the population characteristics of the species that dominate the coral assemblages in both national parks, such as those of fast population growth and of small colony size, do not entirely fulfill the main function of accretion and habitat heterogeneity, and more research is therefore needed to test this hypothesis.Evaluar la respuesta de las comunidades de coral a diferentes perturbaciones es importante ya que las variaciones en la composición de las especies pueden tener consecuencias en el funcionamiento del ecosistema, debido a los diferentes roles funcionales que cada especie tiene dentro de él. En este estudio se evaluaron los cambios en la diversidad, estructura y composición de las comunidades en los arrecifes de dos Parques Nacionales ubicados en el sector norte del Sistema Arrecifal Mesoamericano, durante el periodo 2006-2012, justo después del impacto de dos huracanes en la zona. En el Parque Nacional Cancún se registraron pocas especies de coral y una cobertura de coral vivo baja ( < 15%) sin cambios temporales significativos; la especie más dominante en este parque fue Porites astreoides con más del 40% de cobertura relativa. Por otro lado, los arrecifes de coral del Parque Nacional de Cozumel mostraron un incremento en la cobertura de coral del 16% en 2006 a 29% en 2012; las especies dominantes, y que incrementaron su cobertura en este periodo, fueron Agaricia agaricites, Siderastrea siderea y P. astreoides. Aunque la dinámica de las comunidades de coral fue diferente en ambos parques, es posible que las características poblacionales de las especies que dominan las comunidades de coral en todos los arrecifes no cumplan por completo con las funciones principales de acreción y heterogeneidad de hábitat; sin embargo se necesita más investigación para poder evaluar esta hipótesis
Propuesta para el showroom de la agencia de viajes La Vida en Viajes como ventaja competitiva
En el presente trabajo de investigación, se describe la propuesta de desarrollo de un modelo para showroom de la agencia de viajes “La vida en viajes” , en el que se muestran propuestas de productos, proveedores, mercado meta, acomodo de showroom, etc. Así mismo se describen los procedimiento que fueron utilizados, al igual que las herramientas que se desarrollaron para conseguir resultados positivos para el crecimiento y funcionamiento de la estrategia planteada.ITESO, A.C
Connectivity between white shark populations off Central California, USA and Guadalupe Island, Mexico
Marine animals often move beyond national borders and exclusive economic zones resulting in a need for trans-boundary management spanning multiple national jurisdictions. Highly migratory fish vulnerable to over-exploitation require protections at international level, as exploitation practices can be disparate between adjacent countries and marine jurisdictions. In this study we collaboratively conducted an analysis of white shark connectivity between two main aggregation regions with independent population assessment and legal protection programs; one off central California, USA and one off Guadalupe Island, Mexico. We acoustically tagged 326 sub-adult and adult white sharks in central California (n=210) and in Guadalupe Island (n=116) with acoustic transmitters between 2008-2019. Of the 326 tagged white sharks, 30 (9.20%) individuals were detected at both regions during the study period. We used a Bayesian implementation of logistic regression with a binomial distribution to estimate the effect of sex, maturity, and tag location to the response variable of probability of moving from one region to the other. While nearly one in ten individuals in our sample were detected in both regions over the study period, the annual rate of trans-regional movement was low (probability of movement = 0.015 yr-1, 95% credible interval = 0.002, 0.061). Sub-adults were more likely than adults to move between regions and sharks were more likely to move from Guadalupe Island to central California, however, sex, and year were not important factors influencing movement. This first estimation of demographic-specific trans-regional movement connecting US and Mexico aggregations with high seasonal site fidelity represents an important step to future international management and assessment of the northeastern Pacific white shark population as a whole
Direct Measurement of the Top Quark Mass at D0
We determine the top quark mass m_t using t-tbar pairs produced in the D0
detector by \sqrt{s} = 1.8 TeV p-pbar collisions in a 125 pb^-1 exposure at the
Fermilab Tevatron. We make a two constraint fit to m_t in t-tbar -> b W^+bbar
W^- final states with one W boson decaying to q-qbar and the other to e-nu or
mu-nu. Likelihood fits to the data yield m_t(l+jets) = 173.3 +- 5.6 (stat) +-
5.5 (syst) GeV/c^2. When this result is combined with an analysis of events in
which both W bosons decay into leptons, we obtain m_t = 172.1 +- 5.2 (stat) +-
4.9 (syst) GeV/c^2. An alternate analysis, using three constraint fits to fixed
top quark masses, gives m_t(l+jets) = 176.0 +- 7.9 (stat) +- 4.8 (syst)
GeV/C^2, consistent with the above result. Studies of kinematic distributions
of the top quark candidates are also presented.Comment: 43 pages, 53 figures, 33 tables. RevTeX. Submitted to Phys. Rev.
Recommended from our members
The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: cosmological implications of the large-scale two-point correlation function
We obtain constraints on cosmological parameters from the spherically
averaged redshift-space correlation function of the CMASS Data Release 9 (DR9)
sample of the Baryonic Oscillation Spectroscopic Survey (BOSS). We combine this
information with additional data from recent CMB, SN and BAO measurements. Our
results show no significant evidence of deviations from the standard
flat-Lambda CDM model, whose basic parameters can be specified by Omega_m =
0.285 +- 0.009, 100 Omega_b = 4.59 +- 0.09, n_s = 0.96 +- 0.009, H_0 = 69.4 +-
0.8 km/s/Mpc and sigma_8 = 0.80 +- 0.02. The CMB+CMASS combination sets tight
constraints on the curvature of the Universe, with Omega_k = -0.0043 +- 0.0049,
and the tensor-to-scalar amplitude ratio, for which we find r < 0.16 at the 95
per cent confidence level (CL). These data show a clear signature of a
deviation from scale-invariance also in the presence of tensor modes, with n_s
<1 at the 99.7 per cent CL. We derive constraints on the fraction of massive
neutrinos of f_nu < 0.049 (95 per cent CL), implying a limit of sum m_nu < 0.51
eV. We find no signature of a deviation from a cosmological constant from the
combination of all datasets, with a constraint of w_DE = -1.033 +- 0.073 when
this parameter is assumed time-independent, and no evidence of a departure from
this value when it is allowed to evolve as w_DE(a) = w_0 + w_a (1 - a). The
achieved accuracy on our cosmological constraints is a clear demonstration of
the constraining power of current cosmological observations.Comment: 26 pages, 15 figures. Minor changes to match version accepted by
MNRA
Search for Squarks and Gluinos in Events Containing Jets and a Large Imbalance in Transverse Energy
Using data corresponding to an integrated luminosity of 79 pb-1, D0 has
searched for events containing multiple jets and large missing transverse
energy in pbar-p collisions at sqrt(s)=1.8 TeV at the Fermilab Tevatron
collider. Observing no significant excess beyond what is expected from the
standard model, we set limits on the masses of squarks and gluinos and on the
model parameters m_0 and m_1/2, in the framework of the minimal low-energy
supergravity models of supersymmetry. For tan(beta) = 2 and A_0 = 0, with mu <
0, we exclude all models with m_squark < 250 GeV/c^2. For models with equal
squark and gluino masses, we exclude m < 260 GeV/c^2.Comment: 10 pages, 3 figures, Submitted to PRL, Fixed typo on page bottom of
p. 6 (QCD multijet background is 35.4 events
Search for Charged Higgs Bosons in Decays of Top Quark Pairs
We present a search for charged Higgs bosons in decays of pair-produced top
quarks using 109.2 +- 5.8 pb^-1 of data recorded from ppbar collisions at
sqrt{s} = 1.8 TeV by the D0 detector during 1992-96 at the Fermilab Tevatron.
No evidence is found for charged Higgs production, and most parts of the
[m(H+),tan(beta)] parameter space where the decay t -> bH+ has a branching
fraction close to or larger than that for t -> bW+ are excluded at 95%
confidence level. Assuming m(t) = 175 GeV and sigma(ppbar -> ttbar) = 5.5 pb,
for m(H+) = 60 GeV, we exclude tan(beta) 40.9.Comment: 11 pages, 3 figures, submitted to PR
- …