The hydrostatic equilibrium and Tsallis equilibrium for self-gravitating systems

Self-gravitating systems are generally thought to behavior non-extensively due to the long-range nature of gravitational forces. We obtain a relation between the nonextensive parameter q of Tsallis statistics, the temperature gradient and the gravitational potential based on the equation of hydrostatic equilibrium of self-gravitating systems. It is suggested that the nonextensive parameter in Tsallis statistics has a clear physical meaning with regard to the non-isothermal nature of the systems with long-range interactions and Tsallis equilibrium distribution for the self-gravitating systems describes the property of hydrostatic equilibrium of the systems.Comment: 7 pages, 9 Reference

Nonextensivity and Galaxy Clustering in the Universe

We investigate two important questions about the use of the nonextensive thermostatistics (NETS) formalism in the context of nonlinear galaxy clustering in the Universe. Firstly, we define a quantitative criterion for justifying nonextensivity at different physical scales. Then, we discuss the physics behind the ansatz of the entropic parameter $q(r)$. Our results suggest the approximate range where nonextensivity can be justified and, hence, give some support to the applicability of NETS to the study of large scale structures.Comment: 8 pages, written version of a talk presented in the International Workshop on Trends and Perspectives on Extensive and Non-Extensive Statistical Mechanics. Accepted for publication in Physica

Multiscaling And Nonextensivity Of Large-scale Structures In The Universe

There has been a trend in the past decade to describe the large-scale structures in the Universe as a (multi)fractal set. However, one of the main objections raised by the opponents of this approach deals with the transition to homogeneity. Moreover, they claim there is not enough sampling space to determine a scaling index which characterizes a (multi)fractal set. In this work we propose an alternative solution to this problem, using the generalized thermostatistics formalism. We show that applying the idea of nonextensivity, intrinsic to this approach, it is possible to derive an expression for the correlation function, describing the scaling properties of large-scale structures in the Universe and the transition to homogeneity, which is in good agreement with observational data. © 2002 Elsevier Science B.V. All rights reserved.168-169404409Coleman, P.H., Pietronero, L., Sanders, R.H., (1988) Astron. Astrophys., 200, pp. L32Wu, K.K.S., Ofer, L., Rees, M.J., (1999) Nature, 397, p. 225Martinez, V.J., (1999) Science, 284, p. 445Smoot, G., (1992) Astrophys. J., 396, pp. L1Guzzo, L., (1997) New Astron., 6, p. 517Labini, F.S., Montuori, M., Pietronero, L., (1998) Phys. Rep., 293, p. 61Davis, M., Critical dialogues in cosmology (1997) Proceedings of the Conference, p. 13. , N. Turok (Ed.), Princeton, NJ, 24-27 June 1996, World Scientific, SingaporeWeinberg, S.E., (1972) Gravitation and Cosmology, , Wiley, New YorkMartinez, V.J., Jones, B.J.T., (1992) Mon. Not. R. Astron. Soc., 242, p. 517Martinez, V.J., (1995) Science, 269, p. 1245Pan, J., Coles, P., (2000) Mon. Not. R. Astron. Soc., 318, pp. L51Gehman, C.S., Langer, W.D., Anderson, C.H., (1998) Astron. Astrophys. Suppl., 193, p. 7204Drazin, P.G., (1992) Nonlinear Systems, , Cambridge University Press, CambridgeItoh, M., (1990) Publ. Astron. Soc. Jpn., 42, p. 481Tsallis, C., (1988) J. Stat. Phys., 52, p. 479Padmanabhan, T., (1990) Phys. Rep., 188, p. 5Plastino, A.R., Plastino, A., (1993) Phys. Lett. A, 174, p. 384Ramos, F.M., Rodrigues Neto, C., Rosa, R.R., cond-mat/9907348, preprint, 1999Ramos, F.M., Rodrigues Neto, C., Rosa, R.R., Abreu Sá, L.D., Bolzan, M.J.A., (2001) Nonlinear Anal., 47, p. 3521Ramos, F.M., Rodrigues Neto, C., Rosa, R.R., Bolzan, M.J.A., Abreu Sá, L.D., Campos Velho, H.F., (2001) Physica A, 295, p. 250Tsallis, C., (1995) Phys. Rev. Lett., 75, p. 3589Tsallis, C., Nonextensive statistical mechanics and thermodynamics: Historical background and present status (2001) Lectures Notes in Physics, , S. Abe, Y. Okamoto (Eds.), Nonextensive Statistical Mechanics and its Applications, Springer, HeidelbergChen, K., Bak, P., cond-mat/9912417, preprint, 1999Bak, P., Chen, K., astro-ph/0001443, preprint, 200

Baryon acoustic oscillations from Integrated Neutral Gas Observations: Broadband corrugated horn construction and testing

International audienceThe Baryon acoustic oscillations from Integrated Neutral Gas Observations (BINGO) telescope is a 40-m class radio telescope under construction that has been designed to measure the large-angular-scale intensity of Hi emission at 980–1260 MHz and hence to constrain dark energy parameters. A large focal plane array comprising of 1.7-metre diameter, 4.3-metre length corrugated feed horns is required in order to optimally illuminate the telescope. Additionally, very clean beams with low sidelobes across a broad frequency range are required, in order to facilitate the separation of the faint Hi emission from bright Galactic foreground emission. Using novel construction methods, a full-sized prototype horn has been assembled. It has an average insertion loss of around − 0.15 dB across the band, with a return loss around 25 dB. The main beam is Gaussian with the first sidelobe at around − 25 dB. A septum polariser to separate the signal into the two hands of circular polarization has also been designed, built and tested

The optical design of the Background Emission Anisotropy Scanning Telescope (BEAST)

We present the optical design of the Background Emission Anisotropy Scanning Telescope (BEAST), an off-axis Gregorian telescope designed to measure the angular distribution of the cosmic microwave background radiation (CMBR) at 30 and 41.5 GHz on angular scales ranging from 20' to 10\ub0. The aperture of the telescope is 1.9 m, and our design meets the strict requirements imposed by the scientific goals of the mission: the beam size is 20' at 41.5 GHz and 26' at 30 GHz, while the illumination at the edge of the mirrors is lower than -30 dB for the central horn. The primary mirror is an off-axis section of a paraboloid, and the secondary an off-axis section of an ellipsoid. A spinning flat mirror located between the sky and the primary provides a two-dimensional chop by rotating the beams around an ellipse on the sky. BEAST uses a receiver array of cryogenic low noise InP High Electron Mobility Transistor (HEMT) amplifiers. The baseline array has seven horns matched to one amplifier each and one horn matched to two amplifiers (two polarizations) for a total of nine amplifiers. Two horns operate around 30 GHz, and six operate around 41.5 GHz. Subsequent campaigns will include 90 GHz and higher frequency channels