Este texto (revisto e atualizado) é baseado em aulas do curso ``Diferentes Aspectos da Relatividade Geral'', ministrado pelo autor no programa de doutorado da Universidade da Côte d’Azur, como parte do projeto de integração da equipe VIRGO em Nice (anteriormente localizada em Saclay), ocorrido em 1996. O presente artigo aborda o efeito Fulling-Davies-Unruh e sua conexão com a radiação Hawking, embora sejam processos distintos. A compreensão do efeito Fulling-Davies-Unruh é essencial na quantização de campos em espaços curvos, objetivo maior deste artigo.
Em Setembro de 2015, os dois conjuntos de espelhos mais perfeitos do mundo moveram-se simultaneamente e da mesma forma, apesar de separados por milhares de quilômetros. Chegara ao fim uma das mais longas buscas da história da ciência. Pela primeira vez a humanidade capturara na Terra uma onda gravitacional. Esta onda foi produzida por um par de buracos negros muito antes do nascimento de Einstein e até de qualquer ser humano. O mundo da física prepara-se agora para uma nova era, em que a astronomia gravitacional nos vai desvendar os segredos sobre as entidades mais misteriosas de todas: os buracos negros.
Context. We have performed a comprehensive multiwavelength analysis of a sample of 20 starburst galaxies that show a substantial population of very young massive stars, most of them classified as Wolf-Rayet (WR) galaxies. Aims. We have analysed optical/NIR colours, physical and chemical properties of the ionized gas, stellar, gas and dust content, star-formation rate and interaction degree (among many other galaxy properties) of our galaxy sam- ple using multi-wavelength data. We compile 41 independent star-forming regions -with oxygen abundances between 12+log(O/H)= 7.58 and 8.75-, of which 31 have a direct estimate of the electron temperature of the ionized gas. Methods. This paper, only submitted to astro-ph, compiles the most common empirical calibrations to the oxygen abundance, and presents the comparison between the chemical abundances derived in these galaxies using the direct method with those obtained through empirical calibrations, as it is published in Lopez-Sanchez & Esteban (2010b). Results. We find that (i) the Pilyugin method (Pilyugin 2001a,b; Pilyugin & Thuan 2005), which considers the R23 and the P parameters, is the best suited empirical calibration for these star-forming galaxies, (ii) the relations between the oxygen abundance and the N2 or the O3N2 parameters provided by Pettini & Pagel (2004) give acceptable results for objects with 12+log(O/H)>8.0, and (iii) the results provided by empirical calibrations based on photoionization models (McGaugh, 1991; Kewley & Dopita, 2002; Kobulnicky & Kewley, 2004) are systematically 0.2 - 0.3 dex higher than the values derived from the direct method. These differences are of the same order that the abundance discrepancy found between recombination and collisionally excited lines. This may suggest the existence of temperature fluctuations in the ionized gas, as exists in Galactic and other extragalactic Hii regions. Conclusions. All these results are included in the paper Massive Star Formation in Wolf-Rayet galaxies IV. Colours, chemical-composition analysis and metallicity-luminosity relations, Lopez-Sanchez & Esteban (2010b), A&A, in press (Sect. 4.4 and Appendix A). Please, if this information is used, reference that paper and NOT this document, which have been only submitted to astro-ph to emphasize these results.
The process by which discoveries are made and accepted is central to progress in astronomy. The manner in which papers are refereed, telescope time is awarded, and research funds are allocated evolves (at best) slowly with time, lacking a systematic procedure by which it is evaluated and modified. It would benefit from greater diversity, e.g., witness the great success of astro-ph. The culture by which astronomy is done should be subjected from time to time to the same scrutiny as research proposals and journal publications. Decadal surveys, in those countries that undertake them, should be a good mechanism for conducting such process assessment and recommending change. Accelerating the Rate of Astronomical Discovery sps5 Rio de Janeiro, Brazil
This is a report on the findings of the dark matter science working group for the white paper on the status and future of TeV gamma-ray astronomy. The white paper was commissioned by the American Physical Society, and the full white paper can be found on astro-ph (arXiv:0810.0444). This detailed section discusses the prospects for dark matter detection with future gamma-ray experiments, and the complementarity of gamma-ray measurements with other indirect, direct or accelerator-based searches. We conclude that any comprehensive search for dark matter should include gamma-ray observations, both to identify the dark matter particle (through the characteristics of the gamma-ray spectrum) and to measure the distribution of dark matter in galactic halos.
In an analysis of the IRAS 1.2 Jy redshift catalogue, with emphasis on the separate examination of northern and southern parts (in galactic coordinates), we found that the clustering of galaxies differs significantly between north and south, showing fluctuations in the clustering properties at least on scales of 100 Mpc/h (Kerscher et al. 1997, astro-ph/9704028). We give a brief description of our morphological method which is based on Minkowski functionals and show the results obtained from the IRAS 1.2 Jy galaxy catalogue. We discuss several error estimates and select different subsamples from the 1.2 Jy catalogue according to flux and colour and validate the results for the whole sample. Furthermore we look closer at the spatial origin of the fluctuation and we compare with optically selected galaxies from the CfA1 survey.
In late 1997 I reported (Mod. Phys. Lett. A 12 (1997) 2919; astro-ph/9806280) the discovery of A New Redshift Interpretation (NRI) of the Hubble relation and the 2.7K CBR, which showed for the first time that it was possible to explain these phenomena within the framework of a universe governed by Einstein's static-spacetime general relativity (GR) instead of the Friedmann-Lemaitre expanding-spacetime paradigm. More recently Carlip and Scranton (astro-ph/9808021; C&S) claim to find flaws in this discovery, while also claiming the standard cosmology is error free. Their analysis assumes the NRI represents a static cosmological model of the universe. This is wrong. My MPLA report clearly states the NRI encompasses an expanding universe wherein galaxies are undergoing Doppler recession due to vacuum density repulsion. C&S's confusion on this crucial point leads to serious errors in their analysis. Next, in claiming the standard cosmology is error free, C&S fail to respond to the contradictory evidence in my preprint, gr-qc/9806061. There I first show why the universe is governed by Einstein static-spacetime GR, and not the Friedmann-Lemaitre expanding spacetime paradigm on which Big Bang cosmology is critically hinged. Secondly, I note a most embarrassing fact about the F-L paradigm--namely, that it has always involved gargantuan nonconservation-of-energy losses amounting to the mass equivalent of about thirty million universes, each with a mass of 10^21 suns.
Extreme speed profiles, that are impossible to anayze correctly using the usual methods, are shown to be easily handled using the methods developed previously by Nicholson (astro-ph/0006330). These profiles are constant orbital speeds with sharp and smooth ramps at the origin, and constant angular velocity with speeds increasing linearly to the galaxy rim. Also an example using measured data for a real galaxy is shown for NGC 3198. A new format is presented to show results in dimensionless form, that includes a way to show SMD results so they are easily compared. Based on repeated trials for accuracy, the rod representing the mass of a fundamental segment is now placed at 0.575*dr at the center ring of a galaxy.
Bekenstein's (2004) TeVeS theory has added an interesting twist to the search for dark matter and dark energy, modifying the landscape of gravity-related astronomy day by day. Built bottom-up rather than top-down as most gravity theories, TeVeS-like theories are healthily rooted on empirical facts, hence immediately passing sanity checks on galaxy rotation curves, solar system constraints, even bullet cluster of galaxies and cosmology with the help of 2eV neutrinos. Nonetheless, empirical checks are far from perfect and complete, and groups of different expertises are rapidly increasing the number of falsifiable properties of the theory. The theory has also been made much simpler and more general thanks to the work of Zlosnik, Ferreira, Starkman (gr-qc/0606039, astro-ph/0607411). Here I attempt a tutorial of how to compute lensing convergence, time delays etc in TeVeS-like theories for non-spherical lenses. I gave examples to illustrate a few common caveats of Dark-Matter-guided intuitions.
We summarize our detailed, physically grounded, model for the early co-evolution of spheroidal galaxies and of active nuclei at their centers (astro-ph/0307202). Our predictions are excellent agreement with observations for a number of observables which proved to be extremely challenging for all the current semi-analytic models, including the sub-mm counts and the corresponding redshift distributions, and the epoch-dependent K-band luminosity function of spheroidal galaxies. Also, the black hole mass function and the relationship between the black hole mass and the velocity dispersion in the galaxy are nicely reproduced.
[NOTE: This 1983 preprint is being uploaded to arXiv.org after the death of its author, who supported online distribution of his work. Contact info of the submitter is at this http URL .] The positions of neutron resonances have been shown to be highly sensitive to the variation of fundamental nuclear constants. The analysis of the measured isotopic shifts in the natural fossil reactor at Oklo gives the following restrictions on the possible rates of the interaction constants variation: strong ~2x10^-19 yr^-1, electromagnetic ~5x10^-18 yr^-1, weak ~10^-12 yr^-1. These limits permit to exclude all the versions of nuclear constants contemporary variation discussed in the literature. URL: this http URL >. For more recent analyses see hep-ph/9606486, hep-ph/0205206 and astro-ph/0204069 .