118556020
The mesotrons of eddington
SummarySome aspects of Eddington’s fundamental theory are reviewed. It is shown that an electrically neutral particle of rest mass close to that of π0-meson can be predicted using a quadruple phase reference frame. An attempt is made to calculate the lifetimes of the π-mesons using an extension of Eddington’s arguments.RiassuntoSi considerano alcuni aspetti della teoria fondamentale di Eddington. Si dimostra che si può prevedere una particella elettricamente neutra con massa a riposo prossima a quella del mesone π0 usando un sistema di riferimento della fase quadruplo. Si tenta di calcolare la vita dei mesoni π con un’estensione degli argomenti di Eddington.РеэюмеЗаново рассматриваются некоторые аспекты фундаментальной теории Эддингтона. Покаэывается, что может быть предскаэана масса покоя злектрически нейтральной частицы, блиэкая к массе π0 меэона, при испольэовании системы отсчета квадруплетной фаэы. Предпринимается попытка вычислить времена жиэни π меэонов, испольэуя обобшение аргументов Эддингтона.
116491269
Spherical symmetry in Rainich's theory
121340458
Some cosmological solutions of a scalar-tensor theory of gravitation
Some cosmological solutions of the scalar-tensor theory of gravitation are derived. The results differ from Friedmann and Brans-Dicke cosmologies, though not sufficiently to enable an immediate decision between these theories to be made. In the case of the solar system the new theory is a special case of theories discussed by Bergmann and Wagoner.
14536809
A multiwavelength study of Swift GRB 060111B constraining the origin of its prompt optical emission
In this work, we present the results obtained from a multi-wavelength campaign, as well as from the public Swift/BAT, XRT, and UVOT data of GRB 060111B for which a bright optical emission was measured with good temporal resolution during the prompt phase. We identified the host galaxy at R~25 mag; its featureless spectral continuum and brightness, as well as the non-detection of any associated supernova 16 days after the trigger and other independent redshift estimates, converge to z~1-2. From the analysis of the early afterglow SED, we find that non-negligible host galaxy dust extinction, in addition to the Galactic one, affects the observed flux in the optical regime. The extinction-corrected optical-to-gamma-ray spectral energy distribution during the prompt emission shows a flux density ratio $F_{\gamma}/F_{opt}$=0.01-0.0001 with spectral index $\beta_{\gamma,opt}> \beta_{\gamma}$, strongly suggesting a separate origin of the optical and gamma-ray components. This result is supported by the lack of correlated behavior in the prompt emission light curves observed in the two energy domains. The properties of the prompt optical emission observed during GRB 060111B favor interpretation of this optical light as radiation from the reverse shock in a thick shell limit and in the slow cooling regime. The expected peak flux is consistent with the observed one corrected for the host extinction, likely indicating that the starting time of the TAROT observations is very near to or coincident with the peak time. The estimated fireball initial Lorentz factor is >260-360 at z=1-2, similar to the Lorentz factors obtained from other GRBs. GRB 060111B is a rare, good test case of the reverse shock emission mechanism in both the X-ray and optical energy ranges.
18079334
Continuous optical monitoring during the prompt emission of GRB 060111B
We present the time-resolved optical emission of GRB 060111B during its prompt phase, measured with the TAROT robotic observatory. This is the first time that the optical emission from a gamma-ray burst has been continuously monitored with a temporal resolution of a few seconds during the prompt gamma-ray phase. The temporal evolution of the prompt optical emission at the level of several seconds is used to provide a clue to the origin of this emission. The optical emission was found to decay steadily from our first measure, 28s after the trigger, in contrast to the gamma-ray emission, which exhibits strong variability at the same time. This behaviour strongly suggests that the optical emission is due to the reverse shock.
117717977
Optically Selected GRB Afterglows, a Real Time Analysis System at the CFHT
We attempt to detect optical GRB afterglows on images taken by the Canada France Hawaii Telescope for the Very Wide survey, component of the Legacy Survey. To do so, a Real Time Analysis System called "Optically Selected GRB Afterglows" has been installed on a dedicated computer in Hawaii. This pipeline automatically and quickly analyzes Megacam images and extracts from them a list of variable objects which is displayed on a web page for validation by a member of the collaboration. The Very Wide survey covers 1200 square degrees down to i'=23.5. This paper briefly explain the RTAS process.
118950262
Detection of a very bright optical flare from a gamma-ray burst at redshift 6.29
In this letter we discuss the flux and the behavior of the bright optical flare emission detected by the 25 cm TAROT robotic telescope during the prompt high-energy emission and the early afterglow. We combine our data with simultaneous observations performed in X-rays and we analyze the broad-band spectrum. These observations lead us to emphasize the similarity of GRB 050904 with GRB 990123, a remarkable gamma-ray burst whose optical emission reached 9th magnitude. While GRB 990123 was, until now, considered as a unique event, this observation suggests the existence of a population of GRBs which have very large isotropic equivalent energies and extremely bright optical counterparts. The luminosity of these GRBs is such that they are easily detectable through the entire universe. Since we can detect them to very high redshift even with small aperture telescopes like TAROT, they will constitute powerful tools for the exploration of the high-redshift Universe and might be used to probe the first generation of stars.
18597318
Stellar evolution through the ages: period variations in galactic RRab stars as derived from the GEOS database and TAROT telescopes
Context. The theory of stellar evolution can be more closely tested if we have the opportunity to measure new quantities. Nowadays, observations of galactic RR Lyr stars are available on a time baseline exceeding 100 years. Therefore, we can exploit the possibility of investigating period changes, continuing the pioneering work started by V. P. Tsesevich in 1969. Aims. We collected the available times of maximum brightness of the galactic RR Lyr stars in the GEOS RR Lyr database. Moreover, we also started new observational projects, including surveys with automated telescopes, to characterise the O‐C diagrams better. Methods. The database we built has proved to be a very powerful tool for tracing the period variations through the ages. We analyzed 123 stars showing a clear O‐C pattern (constant, parabolic or erratic) by means of different least‐squares methods. Results. Clear evidence of period increases or decreases at constant rates has been found, suggesting evolutionary effects. The median values are �=+0.14 d Myr −1 for the 27 stars showing a period increase and �=‐0.20 d Myr −1 for the 21 stars showing a period decrease. The large number of RR Lyr stars showing a period decrease (i.e., blueward evolution) is a new and intriguing result. There is an excess � � � �