Skip to content

Astrophysics papers — page 4

astro-phBrowse archive

Dissecting cosmic-ray electron-positron data with Occam's Razor: the role of known Pulsars
We argue that both the positron fraction measured by PAMELA and the peculiar spectral features reported in the total electron-positron (e+e-) flux measured by ATIC have a very natural explanation in…
Stefano ProfumoDec 23, 2008
Learn
The very short supersoft X-ray state of the classical nova M31N 2007-11a
Short supersoft X-ray source (SSS) states (durations < 100 days) of classical novae (CNe) indicate massive white dwarfs that are candidate progenitors of supernovae type Ia. We carry out a dedicated…
M. Henze, W. Pietsch, G. Sala et al.Dec 23, 2008
Learn
Testing the predictions of the cold dark matter model for the sizes, colours, morphologies and luminosities of galaxies with the SDSS
The huge size and uniformity of the Sloan Digital Sky Survey makes possible an exacting test of current models of galaxy formation. We compare the predictions of the GALFORM semi-analytical galaxy…
J. E. Gonzalez, C. G. Lacey, C. M. Baugh et al.Dec 23, 2008
Learn
Synchronization mechanism of sharp edges in rings of Saturn
We propose a new mechanism which explains the existence of enormously sharp edges in the rings of Saturn. This mechanism is based on the synchronization phenomenon due to which the epicycle…
D. L. Shepelyansky, A. S. Pikovsky, J. Schmidt et al.Dec 23, 2008
Learn
Gravitational wave background as a probe of the primordial black hole abundance
Formation of significant number of primordial black holes (PBHs) is realized if and only if primordial density fluctuations have a large amplitude, which means that tensor perturbations generated…
Ryo Saito, Jun'ichi YokoyamaDec 23, 2008
Learn
Dynamical and thermal evolution of the quark-nova ejecta
We explore the dynamical and thermal evolution of the ejected neutron star crust in a Quark-Nova explosion. Typical explosion energies and ejected crust masses result in relativistic ejection with…
Rachid Ouyed, Denis LeahyDec 23, 2008
Learn
Black Holes Admitting Strong Resonant Phenomena
High-frequency twin peak quasiperiodic oscillations (QPOs) are observed in four microquasars, i.e., Galactic black hole binary systems, with frequency ratio very close to 3:2. In the microquasar GRS…
Zdenek Stuchlik, Andrea Kotrlova, Gabriel TorokDec 23, 2008
Learn
A model for the Z-track phenomenon in GX 5-1 and observational evidence for the physical origins of the kHz QPO
We present results of a combined investigation of the spectral and kHz QPO evolution around the Z-track in GX 5-1 based on high-quality RXTE data. The Extended ADC emission model provides very good…
N. K. Jackson, M. J. Church, M. Balucinska-ChurchDec 23, 2008
Learn
Abell 851 and the Role of Starbursts in Cluster Galaxy Evolution
We use extensive new observations of the very rich z ~ 0.4 cluster of galaxies A851 to examine the nature and origin of starburst galaxies in intermediate-redshift clusters. New HST observations,…
A. Oemler, A. Dressler, D. Kelson et al.Dec 23, 2008
Learn
The Magnetic Sensitivity of the Second Solar Spectrum
This paper reviews some of the developments that over the last 10 years have allowed us to go from deciphering the physical origin of several of the enigmatic features of the second solar spectrum to…
J. Trujillo BuenoDec 23, 2008
Learn
Disentangling age and metallicity in distant unresolved stellar systems
We present some results of an observational and theoretical study on unresolved stellar systems based on the Surface Brightness Fluctuations (SBF) technique. It is shown that SBF magnitudes are a…
M. Cantiello, E. Brocato, G. RaimondoDec 23, 2008
Learn
The Role of Massive Agb Stars in the Early Solar System Composition
We demonstrate that a massive asymptotic giant branch (AGB) star is a good candidate as the main source of short-lived radionuclides in the early solar system. Recent identification of massive (4-8…
Josep M. Trigo-Rodriguez, Domingo Anibal Garcia-Hernandez, Maria Lugaro et al.Dec 23, 2008
Learn
Two more disk galaxies with global gas counterrotation
We report a discovery of extended counterrotating gaseous disks in early-type disk galaxies NGC 2551 and NGC 5631. To find them, we have undertaken complex spectral observations including…
O. K. Sil'chenko, A. V. Moiseev, V. L. AfanasievDec 23, 2008
Learn
The Role of the Random Magnetic Fields in the ISM: HVCs Numerical Simulations
We know that the galactic magnetic field possesses a random component in addition to the mean uniform component, with comparable strength of the two components. This random component is considered to…
A. Santillan, J. Kim, F. J. Sanchez-Salcedo et al.Dec 23, 2008
Learn
Shape and kinematics of elliptical galaxies: evolution due to merging at z < 1.5
Aims:In this study we investigate the evolution of shape and kinematics of elliptical galaxies in a cosmological framework. Methods: We use a set of hydrodynamic, self-consistent simulations…
A. César González-García, José Oñorbe, Rosa Domínguez-Tenreiro et al.Dec 23, 2008
Learn
High Albedos of Low Inclination Classical Kuiper Belt Objects
We present observations of thermal emission from fifteen transneptunian objects (TNOs) made using the Spitzer Space Telescope. Thirteen of the targets are members of the Classical population: six…
M. J. Brucker, W. M. Grundy, J. A. Stansberry et al.Dec 22, 2008
Learn
Breaking Halo Occupation Degeneracies with Marked Statistics
We show that a suitably defined marked correlation function can be used to break degeneracies in halo-occupation distribution modeling. The statistic can be computed on both 3D and 2D data sets, and…
Martin White, Nikhil PadmanabhanDec 22, 2008
Learn
Study of positrons from cosmic rays interactions and cold dark matter annihilations in the galactic environment
Positron and electron cosmic rays provide a complementary way to study the galactic environment. The actual cosmic rays experiments, for instance PAMELA and HEAT, have presented very exciting results…
Roberto A. LinerosDec 22, 2008
Learn
Mass Ejection by Strange Star Mergers and Observational Implications
We determine the Galactic production rate of strangelets as a canonical input to calculations of the measurable cosmic ray flux of strangelets by performing simulations of strange star mergers and…
A. Bauswein, H. -Th. Janka, R. Oechslin et al.Dec 22, 2008
Learn
Constraints on amplitudes of curvature perturbations from primordial black holes
We calculate the primordial black hole (PBH) mass spectrum produced from a collapse of the primordial density fluctuations in the early Universe using, as an input, several theoretical models giving…
Edgar Bugaev, Peter KlimaiDec 22, 2008
Learn
Keck/HIRES spectroscopy of V838 Monocerotis in October 2005
V838 Mon erupted at the beginning of 2002 becoming an extremely luminous star. Among various scenarios proposed to explain the nature of the outburst the most promising is a stellar merger event. In…
T. Kamiński, M. Schmidt, R. Tylenda et al.Dec 22, 2008
Learn
What is the closest black hole to the Sun?
We examine the distance of the two galactic microquasars GRO J1655-40 and A0620-00, which are potentially the two closest black holes to the Sun. We aim to provide a picture as wide and complete as…
C. FoellmiDec 22, 2008
Learn
Joule Heating and Anomalous Resistivity in the Solar Corona
Recent radioastronomical observations of Faraday rotation in the solar corona can be interpreted as evidence for coronal currents, with values as large as 2.5 × 109 Amperes (Spangler 2007).…
Steven R. SpanglerDec 22, 2008
Learn
Recent Torque Reversal of 4U 1907+09
We present timing and spectral analysis of RXTE-PCA observations of the accretion powered pulsar 4U 1907+09 between June 2007 and August 2008. 4U 1907+09 had been in a spin-down episode with a…
S. C. Inam, S. Sahiner, A. BaykalDec 22, 2008
Learn
Cosmological Evolution of a Tachyon-Quintom Model of Dark Energy
In this work we study the cosmological evolution of a dark energy model with two scalar fields, i.e. the tachyon and the phantom tachyon. This model enables the equation of state w to change from…
Shang-Gang Shi, Yun-Song Piao, Cong-Feng QiaoDec 22, 2008
Learn
← PreviousPage 4Next →