683 research outputs found
ÉTUDE PRÉLIMINAIRE DE L'EFFET D'HÉTÉROSIS ET DE L'EFFET MATERNEL SUR LE CARACTÈRE DE PROLIFICITÉ DES BREBIS EN CROISEMENT RÉCIPROQUE ROMANOV X BERRICHON
Étude préliminaire de l'effet d'hétérosis et de l'effet maternel sur le caractère de prolificité des brebis en croisement réciproque Romanov × Berrichon
Spin frequency evolution and pulse profile variations of the recently re-activated radio magnetar XTE J1810-197
After spending almost a decade in a radio-quiet state, the Anomalous X-ray
Pulsar XTE J1810-197 turned back on in early December 2018. We have observed
this radio magnetar at 1.5 GHz with ~daily cadence since the first detection of
radio re-activation on 8 December 2018. In this paper, we report on the current
timing properties of XTE J1810-197 and find that the magnitude of the spin
frequency derivative has increased by a factor of 2.6 over our 48-day data set.
We compare our results with the spin-down evolution reported during its
previous active phase in the radio band. We also present total intensity pulse
profiles at five different observing frequencies between 1.5 and 8.4 GHz,
collected with the Lovell and the Effelsberg telescopes. The profile evolution
in our data set is less erratic than what was reported during the previous
active phase, and can be seen varying smoothly between observations. Profiles
observed immediately after the outburst show the presence of at least five
cycles of a very stable ~50-ms periodicity in the main pulse component that
lasts for at least tens of days. This remarkable structure is seen across the
full range of observing frequencies.Comment: 9 pages, 7 figures, updated with additional analysis of the 50-ms
oscillation, accepted for publication in MNRA
Precision timing of PSR J1012+5307 and strong-field GR tests
We report on the high precision timing analysis of the pulsar-white dwarf
binary PSR J1012+5307. Using 15 years of multi-telescope data from the European
Pulsar Timing Array (EPTA) network, a significant measurement of the variation
of the orbital period is obtained. Using this ideal strong-field gravity
laboratory we derive theory independent limits for both the dipole radiation
and the variation of the gravitational constant.Comment: 3 pages, Proceedings of the 12th Marcel Grossmann Meeting on General
Relativity (MG 12
The INPOP10a planetary ephemeris and its applications in fundamental physics
International audienceCompared to the previous INPOP versions, the INPOP10a planetary and lunar ephemeris has several improvements. For the planets of our solar system, no big change was brought in the dynamics but improvements were implemented in the fitting process, the data sets used in the fit and in the selection of fitted parameters. We report here the main characteristics of the planetary part of INPOP10a like the fit of the product of the Solar mass with the gravitational constant (GM) instead of the astronomical unit. Determinations of PPN parameters as well as adjustments of the Sun J2 and of asteroid masses are also presented. New advances of nodes and perihelia of planets were also estimated and are given here. As for INPOP08, INPOP10a provides to the user, positions and velocities of the planets, the moon, the rotation angles of the Earth and the Moon as well as TT-TDB chebychev polynomials at http://www.imcce.fr/inpo
Estimation des paramètres génétiques de la vitesse de croissance et du poids des agneaux avant le sevrage en race mérinos d'arles
International audienc
Amélioration de la productivité des brebis berrichonnes du cher par croisement. III. – Performances de reproduction des trois premières genérations de brebis croisées entre les races berrichonne du cher et romanov
International audienc
ESTIMATION DES PARAMÈTRES GÉNÉTIQUES DE LA VITESSE DE CROISSANCE ET DU POIDS DES AGNEAUX AVANT LE SEVRAGE EN RACE MÉRINOS D'ARLES
The Discovery of Six Recycled Pulsars from the Arecibo 327-MHz Drift-Scan Pulsar Survey
Recycled pulsars are old ( yr) neutron stars that are
descendants from close, interacting stellar systems. In order to understand
their evolution and population, we must find and study the largest number
possible of recycled pulsars in a way that is as unbiased as possible. In this
work, we present the discovery and timing solutions of five recycled pulsars in
binary systems (PSRs J05090856, J07090458, J07322314, J08240028,
J22042700) and one isolated millisecond pulsar (PSR J01541833). These
were found in data from the Arecibo 327-MHz Drift-Scan Pulsar Survey (AO327).
All these pulsars have a low dispersion measure (DM) (), and have a DM-determined distance of 3 kpc. Their timing
solutions, have data spans ranging from 1 to 7 years, include precise
estimates of their spin and astrometric parameters, and for the binaries,
precise estimates of their Keplerian binary parameters. Their orbital periods
range from about 4 to 815 days and the minimum companion masses (assuming a
pulsar mass of 1.4 ) range from 0.06--1.11
. For two of the binaries we detect post-Keplerian parameters;
in the case of PSR~J07090458 we measure the component masses but with a low
precision, in the not too distant future the measurement of the rate of advance
of periastron and the Shapiro delay will allow very precise mass measurements
for this system. Like several other systems found in the AO327 data, PSRs
J05090854, J07090458 and J07322314 are now part of the NANOGrav timing
array for gravitational wave detection
Placing limits on the stochastic gravitational-wave background using European Pulsar Timing Array data
Direct detection of low-frequency gravitational waves (
Hz) is the main goal of pulsar timing array (PTA) projects. One of the main
targets for the PTAs is to measure the stochastic background of gravitational
waves (GWB) whose characteristic strain is expected to approximately follow a
power-law of the form , where is the
gravitational-wave frequency. In this paper we use the current data from the
European PTA to determine an upper limit on the GWB amplitude as a function
of the unknown spectral slope with a Bayesian algorithm, by modelling
the GWB as a random Gaussian process. For the case , which is
expected if the GWB is produced by supermassive black-hole binaries, we obtain
a 95% confidence upper limit on of , which is 1.8 times
lower than the 95% confidence GWB limit obtained by the Parkes PTA in 2006. Our
approach to the data analysis incorporates the multi-telescope nature of the
European PTA and thus can serve as a useful template for future
intercontinental PTA collaborations.Comment: 14 pages, 8 figures, 3 tables, mnras accepte
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