Suchergebnisse

16 pages, 12 figures.-- PACS nrs.: 14.60.Pq; 97.60.Bw.-- ISI Article Identifier: 000251987300100.-- ArXiv pre-print available at: http://arxiv.org/abs/0706.2498 ; In the dense-neutrino region at 50-400 km above the neutrino sphere in a supernova, neutrino-neutrino interactions cause large flavor transformations. We study when the multiangle nature of the neutrino trajectories leads to flavor decoherence between different angular modes. We consider a two-flavor mixing scenario between nu(e) and another flavor nu(x) and assume the usual hierarchy F-nu e > F-[overline nu][sub e] > F-nu x = F-[overline nu][sub x] for the number fluxes. We define epsilon = (F-nu e - F-[overline nu][sub e])/(F-[overline nu][sub e] - F-[overline nu][sub x]) as a measure for the deleptonization flux which is the one crucial parameter. The transition between the quasi-single-angle behavior and multiangle decoherence is abrupt as a function of epsilon. For typical choices of other parameters, multiangle decoherence is suppressed for epsilon greater than or similar to 0.3, but a much smaller asymmetry suffices if the neutrino mass hierarchy is normal and the mixing angle small. The critical epsilon depends logarithmically on the neutrino luminosity. In a realistic supernova scenario, the deleptonization flux is probably enough to suppress multiangle decoherence. ; This work was partly supported by the Deutsche Forschungsgemeinschaft under the Grant No. TR-27 "Neutrinos and Beyond", by The Cluster of Excellence for Fundamental Physics "Origin and Structure of the Universe" (Garching and Munich), by the European Union under the ILIAS project (Contract No. RII3-CT-2004-506222) and an RT Network (Contract No. MRTNCT-2004-503369), and by the Spanish grants FPA2005-01269 (MEC) and ACOMP07-270 (Generalitat Valenciana). A. E. has been supported by a FPU grant from the Spanish Government. S. P. and R. T. were supported by MEC contracts (Ramón y Cajal and Juan de la Cierva, respectively). ; Peer reviewed

5 pags. ; 1 fig. ; In loop quantum cosmology, non-perturbative quantum gravity effects lead to the resolution of the big bang singularity by a quantum bounce without introducing any new degrees of freedom. Though fundamentally discrete, the theory admits a continuum description in terms of an effective Hamiltonian. Here we provide an algorithm to obtain the corresponding effective action, establishing in this way the covariance of the theory for the first time. This result provides new insights on the continuum properties of the discrete structure of quantum geometry and opens new avenues to extract physical predictions such as those related to gauge invariant cosmological perturbations. ; We are grateful to A. Ashtekar, A. Corichi and B. Dittrich for useful discussions and extensive comments. We thank F. Barbero, R. Maartens, G. Mena-Marug´an and K. Vandersloot for comments. PS also thanks T. Biswas and K. Vandersloot for discussions on metric formulation of the problem. GO has been supported by MICINN. Research of PS is supported by Perimeter Institute for Theoretical Physics. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Research & Innovation. ; Peer reviewed

9 pages, 3 figures.-- ArXiv pre-print available at: http://arxiv.org/abs/0809.0506 ; We use a Press-Schechter-like calculation to study how the abundance of voids changes in models with non-Gaussian initial conditions. While a positive skewness increases the cluster abundance, a negative skewness does the same for the void abundance. We determine the dependence of the void abundance on the non-Gaussianity parameter fnl for the local-model bispectrum —which approximates the bispectrum in some multi-field inflation models— and for the equilateral bispectrum, which approximates the bispectrum in single-field slow-roll inflation and in string-inspired DBI models of inflation. We show that the void abundance in large-scale-structure surveys currently being considered should probe values as small as f(nl) <~ 10 and f(nl)eq <~ 30, over distance scales ~ 10 Mpc. ; This work was supported at Caltech by DoE DE-FG03-92-ER40701 and the Gordon and Betty Moore Foundation. LV thanks M. LoVerde for providing the curves of Fig. 3(a,b) of Ref. [20] in table form. LV is supported by FP7-PEOPLE-2007-4-3 IRG n 202182 and CSIC I3 grant 200750I034. RJ is supported by grants from the Spanish Science Ministry and The European Union (FP7). ; Peer reviewed

ESA ; CNES (France) ; CNRS/INSU-IN2P3-INP (France) ; ASI (Italy) ; CNR (Italy) ; INAF (Italy) ; NASA (USA) ; DoE (USA) ; STFC (UK) ; UKSA (UK) ; CSIC (Spain) ; MINECO (Spain) ; JA (Spain) ; RES (Spain) ; Tekes (Finland) ; AoF (Finland) ; CSC (Finland) ; DLR (Germany) ; MPG (Germany) ; CSA (Canada) ; DTU Space (Denmark) ; SER/SSO (Switzerland) ; RCN (Norway) ; SFI (Ireland) ; FCT/MCTES (Portugal) ; ERC (EU) ; PRACE (EU) ; UK BIS NEI grants ; Office of Science of the U.S. Department of Energy ; Canada Foundation for Innovation under Compute Canada ; Government of Ontario ; University of Toronto ; Science and Technology Facilities Council ; Office of Science of the U.S. Department of Energy: DE-AC02-05CH11231 ; Science and Technology Facilities Council: ST/L000768/1 ; Science and Technology Facilities Council: ST/L000652/1 ; Science and Technology Facilities Council: ST/J005673/1 ; Science and Technology Facilities Council: ST/M00418X/1 ; Science and Technology Facilities Council: ST/L000393/1 ; Science and Technology Facilities Council: ST/M007065/1 ; Science and Technology Facilities Council: ST/K00333X/1 ; The Planck full mission cosmic microwave background (CMB) temperature and E-mode polarization maps are analysed to obtain constraints on primordial non-Gaussianity (NG). Using three classes of optimal bispectrum estimators - separable template-fitting (KSW), binned, and modal we obtain consistent values for the primordial local, equilateral, and orthogonal bispectrum amplitudes, quoting as our final result from temperature alone f(NL)(local) = 2.5 +/- 5.7, f(NL)(equil) = 16 +/- 70, and f(NL)(ortho) = 34 +/- 33 (68% CL, statistical). Combining temperature and polarization data we obtain f(NL)(local) = 0.8 +/- 5.0, f(NL)(equil) = 4 +/- 43, and f(NL)(ortho) = 26 +/- 21 (68% CL, statistical). The results are based on comprehensive cross-validation of these estimators on Gaussian and non-Gaussian simulations, are stable across component separation techniques, pass an extensive suite of tests, and are consistent with estimators based on measuring the Minkowski functionals of the CMB. The effect of time-domain de-glitching systematics on the bispectrum is negligible. In spite of these test outcomes we conservatively label the results including polarization data as preliminary, owing to a known mismatch of the noise model in simulations and the data. Beyond estimates of individual shape amplitudes, we present model-independent, three-dimensional reconstructions of the Planck CMB bispectrum and derive constraints on early universe scenarios that generate primordial NG, including general single-field models of inflation, axion inflation, initial state modifications, models producing parity-violating tensor bispectra, and directionally dependent vector models. We present a wide survey of scale-dependent feature and resonance models, accounting for the look elsewhere effect in estimating the statistical significance of features. We also look for isocurvature NG, and find no signal, but we obtain constraints that improve significantly with the inclusion of polarization. The primordial trispectrum amplitude in the local model is constrained to be g(NL)(local) = (9.0 +/- 7.7) x 10(4) (68% CL statistical), and we perform an analysis of trispectrum shapes beyond the local case. The global picture that emerges is one of consistency with the premises of the Lambda CDM cosmology, namely that the structure we observe today was sourced by adiabatic, passive, Gaussian, and primordial seed perturbations.

Cold Dark Matter with cosmological constant (ΛCDM) cosmological models with early dark energy (EDE) have been proposed to resolve tensions between the Hubble constant H 0=100, h km -1pc-1 measured locally, giving h ≈ 0.73, and H0 deduced from Planck cosmic microwave background (CMB) and other early-Universe measurements plus ΛCDM, giving h ≈ 0.67. EDE models do this by adding a scalar field that temporarily adds dark energy equal to about 10 per cent of the cosmological energy density at the end of the radiation-dominated era at redshift z ∼3500. Here, we compare linear and non-linear predictions of a Planck-normalized ΛCDM model including EDE giving h = 0.728 with those of standard Planck-normalized ΛCDM with h = 0.678. We find that non-linear evolution reduces the differences between power spectra of fluctuations at low redshifts. As a result, at z = 0 the halo mass functions on galactic scales are nearly the same, with differences only 1-2 per cent. However, the differences dramatically increase at high redshifts. The EDE model predicts 50 per cent more massive clusters at z = 1 and twice more galaxy-mass haloes at z = 4. Even greater increases in abundances of galaxy-mass haloes at higher redshifts may make it easier to reionize the universe with EDE. Predicted galaxy abundances and clustering will soon be tested by the James Webb Space Telescope (JWST) observations. Positions of baryonic acoustic oscillations (BAOs) and correlation functions differ by about 2 per cent between the models-an effect that is not washed out by non-linearities. Both standard ΛCDM and the EDE model studied here agree well with presently available acoustic-scale observations, but the Dark Energy Spectroscopic Instrument and Euclid measurements will provide stringent new tests. © 2021 The Author(s). ; AK and FP thank the support of the Spanish Ministry of Science funding grant PGC2018-101931-B-I00. This work used the skun6@IAA facility managed by the Instituto de Astrofísica de Andalucía (CSIC). The equipment was funded by the Spanish Ministry of Science EU-FEDER infrastructure grantEQC2018-004366-P. MK acknowledges the support of NSF Grant No. 1519353, NASA NNX17AK38G, and the Simons Foundation. TLS acknowledges support from NASA (through grant 80NSSC18K0728) and the Research Corporation. We thank Alexie Leauthaud and Johannes Lange for a helpful discussion about weak lensing results. ; With funding from the Spanish government through the Severo Ochoa Centre of Excellence accreditation SEV-2017-0709. ; Peer reviewed

In his recent essay, Mark Wenman highlighted parallels between Connolly's theory of pluralism and earlier iterations of pluralism in the postwar period and the early twentieth century. Focusing on his account of postwar pluralism and especially his interpretation of Dahl, I argue that Dahl's vision of democracy as polyarchy is fundamentally at odds with Connolly's. A close reading of Dahl's text and a consideration of the historical context suggest that Dahl's theory effectively creates a depoliticized world where citizens are unresponsive to claims about alternative possibilities of democratic life.

Every saga has a beginning: philosophical cosmologies in the ancient world -- The voyage home: cosmos in early Christian thought -- Resistance is futile: Galileo, Newton, and Darwin -- All these worlds: on the multiverse -- If it's just us, it seems like an awful waste of space: on human uniqueness -- Infinite space, infinite terror: our cosmic (in)significance -- In space no one can hear you scream? God and being -- There is no gene for the human spirit: images of God -- Come with me if you want to live: incarnations -- To boldly go: beings in search of greater understanding

In essence, primordial black holes generated in the early Universe as a result of a gravitational collapse of the high-density matter are detectors of the processes proceeding in it. As these black holes are generated at high energies (close to the Planck energies) and their radii are small, there is a need to take into consideration the quantum-gravitational corrections for them. In this paper, within the scope of the Generalized Uncertainty Principle, the author continues a study of the quantum-gravitational corrections and their contributions into the inflationary parameters for primordial black holes in the pre-inflationary epoch. Specifically, within this pattern, the author considers a case of Hawking's radiation (evaporation) for the above-mentioned black holes and derives formulae for the corresponding changes ("shifts") of the basic inflation parameters. In all cases the expressions for the corresponding correction of е-foldings in an inflation model have been found. In conclusion the main problems for further studies are formulated.

Ultra-Luminous X-ray sources (ULXs) are accreting black holes for which their X-ray properties have been seen to be different to the case of stellar-mass black hole binaries. For most of the cases their intrinsic energy spectra are well described by a cold accretion disc (thermal) plus a curved high-energy emission components. The mass of the black hole (BH) derived from the thermal disc component is usually in the range of 100-105 solar masses, which have led to the idea that this can represent strong evidence of the Intermediate Mass Black Holes (IMBH), proposed to exist by theoretical studies but with no firm detection (as a class) so far. Recent theoretical and observational developments are leading towards the idea that these sources are instead compact objects accreting at an unusual super-Eddington regime instead. On the other hand, gravitational waves have been seen to be a useful tool for finding (some of these) IMBHs. We give a brief overview about the recent advent of the discovery of gravitational waves and their relationship with these so far elusive IMBHs.© 2017 Universidad Nacional Autonoma de Mexico. All rights reserved ; MCG, MB and MD acknowledge support provided by the European Seventh Frame -work Programme (FP7/2007-2013) under grant agreement no 312789 and GA CR grant 18-005335. SF acknowledges support by the Russian Science Foundation (N 14-50-00043) and the Russian Government Program of Competitive Growth of KFU. AJCT acknowledges support from the Spanish MINECO Ministry project: AYA2015-71718-R.

4 pages, 1 table.-- PACS nrs.: 98.80.Cq, 04.62.+v.-- PMID: 18999735 [PubMed]. ; We find that the amplitude of quantum fluctuations of the invariant de Sitter vacuum coincides exactly with that of the vacuum of a comoving observer for a massless scalar (inflaton) field. We propose redefining the actual physical power spectrum as the difference between the amplitudes of the above vacua. An inertial particle detector continues to observe the Gibbons-Hawking temperature. However, although the resulting power spectrum is still scale-free, its amplitude can be drastically reduced since now, instead of the Hubble's scale at the inflationary period, it is determined by the square of the mass of the inflaton fluctuation field. ; This work has been partially supported by Grants FIS2005-05736-C03-03 and EU network MRTN-CT- 2004-005104. L. Parker has been partially supported by NSF Grants PHY-0071044 and PHY-0503366. I.A. and G. O. thank MICINN for an FPU grant and a JdC contract, respectively. G.O. has also been supported by Perimeter Institute for Theoretical Physics. Research at Perimeter Institute is supported by the Government of Canada through Industry Canada and by the Province of Ontario through the Ministry of Research & Innovation. ; Peer reviewed

George R. Blumenthal arrived at UC Santa Cruz in 1972 as a young faculty member in astronomy and astrophysics. Thirty-five years later, on September 19, 2007, he became UCSC's tenth chancellor, after serving as acting chancellor for fourteen months. Blumenthal dedicated thirteen years of his life to being chancellor of UC Santa Cruz. This oral history was transcribed from forty interviews recorded between June 2018 and July 2019 and encompasses Chancellor Blumenthal's long and distinguished career at UC Santa Cruz and with the University of California system. Long before he became chancellor, Blumenthal served the campus in diverse capacities; he was the faculty representative to the UC Regents (2003-05); chaired the UC Santa Cruz division of the Academic Senate (2001-03); and served as chair of the Astronomy and Astrophysics Department twice. But not only does this oral history cover almost fifty years of UCSC's history—from the early years of Oakes College under Provost J. Herman Blake, to the impacts of the defunding of public higher education in more recent years—it is also infused with Blumenthal's insider's viewpoint on the University of California system that he gained as vice-chair of the UC Academic Senate (2003-2004); chair of UC Academic Senate (2004-05); and experience serving on many other UC-wide committees and endeavors. In 2010, Blumenthal received the Oliver Johnson Award for Distinguished Leadership in the Academic Senate, the top UC honor for service at both the systemwide and campus levels. This volume is thus both an oral history of UC Santa Cruz and of the University of California system as a whole and is an invaluable primary resource for those seeking to understand the history of both this unique campus in the redwoods and the intricate political history of the University of California system.

One of the world's preeminent cultural anthropologists leaves a last work that fundamentally reconfigures how we study most other culturesFrom the perspective of Western modernity, humanity inhabits a disenchanted cosmos. Gods, spirits, and ancestors have left us for a transcendent beyond, no longer living in our midst and being involved in all matters of everyday life from the trivial to the dire. Yet the vast majority of cultures throughout human history treat spirits as very real persons, members of a cosmic society who interact with humans and control their fate. In most cultures, even today, people are but a small part of an enchanted universe misconstrued by the transcendent categories of "religion" and the "supernatural." The New Science of the Enchanted Universe shows how anthropologists and other social scientists must rethink these cultures of immanence and study them by their own lights.In this, his last, revelatory book, Marshall Sahlins announces a new method and sets an exciting agenda for the field. He takes readers around the world, from Inuit of the Arctic Circle to pastoral Dinka of East Africa, from Araweté swidden gardeners of Amazonia to Trobriand Island horticulturalists. In the process, Sahlins sheds new light on classical and contemporary ethnographies that describe these cultures of immanence and reveals how even the apparently mundane, all-too-human spheres of "economics" and "politics" emerge as people negotiate with, and ultimately usurp, the powers of the gods.The New Science of the Enchanted Universe offers a road map for a new practice of anthropology that takes seriously the enchanted universe and its transformations from ancient Mesopotamia to contemporary America

This dissertation treats the reign of the Ottoman Sultan Ahmed III (1703-1730) in the context of the European early enlightenment. Intellectual historians have generally placed the Ottoman Empire outside the Enlightenment movement, while Ottoman historians have viewed the early eighteenth century as a transitional period between the crisis of the seventeenth century and the reformist movements of the late eighteenth century. The research presented in this work seeks to call these interpretations into question and suggests that the defining features of Ahmed III's regime were similar to those of the early enlightenment : cosmopolitanism, sociability, religious tolerance and, the valorization of philosophy and of social mobility. It was in this enlightened atmosphere that natural philosophy became a contested space where different parties negotiated their new social status: What was the function of natural philosophy? Who could legitimately speak about nature? The Greek commercial elite argued that the Aristotelian universe was an orderly whole and claimed that the rational contemplation of natural order engendered virtue. And virtue legitimized social status. Ottoman physicians, a second group aspiring to high office, contended that their empirical philosophy was superior to Aristotelianism. They believed that their innovative approach to nature was the right one because it yielded effective results. It was experience and effectiveness that entitled them to social and political recognition. Thus, moral virtue and technical expertise became competing values that represented different upwardly mobile groups in Ahmed III's Istanbul. The Ottomans had no experimentalist tradition that could accommodate both logical methods and novel empirical knowledge. A young Ottoman bureaucrat, a Socinian convert to Islam and a Polish Pietist finally presented systematic experimentation as a possible solution to the Empire's social and epistemic problems. Their goal was to reconcile the two competing views of nature and to cultivate solidarity among the new elite. The Ottoman imperial printing press, which was established in 1729, served to disseminate the new experimental knowledge. The founding documents of the press drew an explicit connection between knowledge and political power, and showed that the Sultan intended to offer widespread access to both