Testing dark energy with the Advanced Liquid-mirror Probe of Asteroids, Cosmology and Astrophysics     

Pier Stefano Corasaniti  Marilena LoVerde  Arlin Crotts  Chris Blake 《Monthly notices of the Royal Astronomical Society》2006,369(2):798-804

The Advanced Liquid-mirror Probe of Asteroids, Cosmology and Astrophysics (ALPACA) is a proposed 8-m liquid-mirror telescope surveying  ∼1000 deg²  of the Southern hemisphere sky. It will be a remarkably simple and inexpensive telescope that none the less will deliver a powerful sample of optical data for studying dark energy. The bulk of the cosmological data consist of nightly, high signal-to-noise ratio, multiband light curves of Type Ia supernovae (SNe Ia). At the end of the 3-yr run, ALPACA is expected to collect  ≳100 000  SNe Ia up to   z ∼ 1  . This will allow us to reduce present systematic uncertainties affecting the standard-candle relation. The survey will also provide several other data sets such as the detection of baryon acoustic oscillations in the matter power spectrum and shear weak-lensing measurements. In this preliminary analysis, we forecast constraints on dark energy parameters from SNe Ia and baryon acoustic oscillations. The combination of these two data sets will provide competitive constraints on the dark energy parameters under minimal prior assumptions. Further studies are needed to address the accuracy of weak-lensing measurements.  相似文献   

Flexural response of the Venetian foreland to the Southalpine tectonics along the TRANSALP profile     

C. Barbieri  G. Bertotti  A. Di Giulio  R. Fantoni  R. Zoetemeijer 《地学学报》2004,16(5):273-280

The Venetian Basin was affected by flexure related to the Southalpine shortening phase during the Middle Miocene – Early Pliocene. This downbending is quantified here using a two‐dimensional flexural model. A recently improved data set on basin geometry based on the bottom of the Serravallian–Tortonian clastic wedge, on palaeobathymetry and gravity anomalies is used to constrain the components of flexure and to test the importance of the initial bathymetry in evaluating the contribution of surface loads to deflection. A good fit is obtained assuming a northward broken plate configuration of the downbent Adriatic plate with an effective elastic thickness of 20 km. Results highlight that, in the studied region, flexure related to the Eastern Southern Alps is totally due to surface loads (topographic load partly replacing initial bathymetry) and that no hidden loads are required. Furthermore, the palaeobathymetry contributes up to 50% to the total flexure in the studied region.  相似文献   

Visible and near-infrared spectroscopic investigation of near-Earth objects at ESO: first results     

M. Lazzarin  S. Marchi  M. Di Martino 《Icarus》2004,169(2):373-384

Near-Earth objects (NEOs) represent one of the most intriguing populations of Solar System bodies. These objects appear heterogeneous in all aspects of their physical properties, like shapes, sizes, spin rates, compositions etc. Moreover, as these objects represent also a real threat to the Earth, a good knowledge of their properties and composition is the necessary first step to evaluate mitigation techniques and to understand their origin and evolution. In the last few years we have started a long-term spectroscopic investigation in the visible and near-infrared (NIR) region of near-Earth objects. The observations have been performed with the 3.5 m NTT of the European Southern Observatory of La Silla (Chile). The data presented here are a set of 24 spectra, 14 of which are both visible and NIR. We discuss the taxonomic classification of the observed NEOs, resulting in 13 S-type objects, 1 Q-type, 2 K-types, 3 C-types, 5 Xe-types (two of these, (3103) Eger and (4660) Nereus, are already known as E-types). Moreover, we discuss their links with meteorites and the possible influences of space weathering.  相似文献   

Linux嵌入式系统根文件系统的选择与制作     

冯世奎  刘玓 《成都信息工程学院学报》2006,21(4):508-512

Linux操作系统做为嵌入式系统近年应用越来越广泛，Linux根文件系的装载是Linux内核启动期间进行的最后操作之一，它是Linux嵌入式系统的一个重要组成部分，系统地分析了Linux嵌入式系统根文件系统的类型，内容选择以及制作方法。  相似文献   

The 21-cm emission from the reionization epoch: extended and point source foregrounds     

Tiziana Di Matteo  Benedetta Ciardi  Francesco Miniati 《Monthly notices of the Royal Astronomical Society》2004,355(4):1053-1065

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三峡数字地震台网中心记录典型波形初步分析   总被引：10，自引：6，他引：4  

狄莉莎 《大地测量与地球动力学》2004,24(2):52-57

对三峡地区数字地震台网中心记录的典型的天然地震、疑炮、一次爆破及一次滑坡等波形进行初步分析后认为：①数字地震仪器与模拟地震仪器所记录的地震波形特征基本一致；②三峡地区数字地震台网中心2003年5月19日至2004年1月所记录的多数天然地震事件是非构造型(由溶洞塌陷引起的陷落型)地震事件。  相似文献   

Evolution of a neutrino-cooled disc in gamma-ray bursts     

A. Janiuk  R. Perna  T. Di Matteo  B. Czerny 《Monthly notices of the Royal Astronomical Society》2004,355(3):950-958

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Fault‐bend folding as an end‐member solution of (double‐edge) fault‐propagation folding     

Stefano Tavani  Fabrizio Storti 《地学学报》2006,18(4):270-275

Fault‐bend folding is the most commonly used kinematic mechanism to interpret the architecture and evolution of thrust‐related anticlines in thrust wedges. However, its basic requirement of an instantaneous propagation of the entire fault before hangingwall deformation, limits its kinematic effectiveness. To overcome this limitation, we used the interdependence between fold shape and fault slip vs. propagation rate (S/P ratio) implemented in double‐edge fault‐propagation folding. We show that very small S/P values produce fault‐propagation anticlines that, when transported forelandward along an upper décollement layer, closely resemble fault‐bend anticlines. Accordingly, if small geometric discrepancies between the two solutions are accepted, transported double‐edge fault‐propagation provides an effective kinematic alternative to fault‐bend folding. Even at very low S/P values, it in fact predicts a fast but finite propagation rate of the fault. We thus propose that double‐edge fault‐propagation folding provides a broadly applicable model of fault‐related folding that includes fault‐bend folding as an end‐member kinematic solution. Terra Nova, 18, 270–275, 2006  相似文献   

A comparative study of the electron and photon components in photon-induced air showers     

G. Di Sciascio  B. D'Ettorre Piazzoli  M. Iacovacci 《Astroparticle Physics》1997,6(3-4):313-322

A detailed simulation of the electromagnetic component of extensive air showers generated by 10¹¹–10¹⁵ eV photons has been carried out by means of the EPAS code. We present and discuss the results concerning the longitudinal, lateral and temporal distributions of electrons and photons down to 1 MeV energy threshold.  相似文献   

The gas mass fraction in local and Z > 0.7 Galaxy Clusters: constraints on Cosmology     

Stefano Ettori 《Astrophysics and Space Science》2004,290(1-2):177-186

We present a study of the baryonic fraction in galaxy clusters aimed at constraining the cosmological parameters Ω_m, Ω_Lgr; and the ratio between the pressure and density of the `dark' energy, w. We use results on the gravitating mass profiles of a sample of nearby galaxy clusters observed with the BeppoSAX X-ray satellite (Ettori, De Grandi and Molendi, 2002)to set constraints on the dynamical estimate of Ω_m. We then analyze Chandra observations of a sample of eight distant clusters with redshift in the range 0.72 and 1.27 and evaluate the geometrical limits on the cosmological parameters Ω_m, Ω_Λ and w by requiring that the gas fraction remains constant with respect to the look-back time. By combining these two independent probability distributions and using a priori distributions on both Ω_b and H ₀ peaked around primordial nucleosynthesis and HST-Key Project results respectively, we obtain that, at 95.4 per cent level of confidence, (i) w < —0.54, (ii)Ω_m = 0.34^+0.11 _—0.05, Ω_Λ = 1.50^+0.24 _—1.13 for w = — 1 (corresponding to the case for a cosmological constant), and (iii) Ω_m = 1 —Ω_Λ = 0.33^+0.06 _—0.05 for a flat Universe. This paper summarizes the work in press at Astronomy & Astrophysics by Ettori, Tozzi and Rosati (astro-ph/0211335).  相似文献