|
| |
arXiv:0711.2655 [ps, pdf, other] :
Title: Simulated all-sky maps of the weak gravitational lensing distortion of the CMB
Authors: Carmelita Carbone, Volker Springel, Carlo Baccigalupi, Matthias Bartelmann, Sabino Matarrese
Comments: LaTeX file, 10 pages, 7 figures, MNRAS submitted
We use the large cosmological Millennium Simulation (MS) to construct the first all-sky maps of the lensing potential and the deflection angle, aiming at gravitational lensing of the CMB. Exploiting the Born approximation, we implement a map-making procedure based on direct ray-tracing through the gravitational potential of the MS. We stack the simulation box in redshift shells up to $z\sim 11$, producing continuous all-sky maps with arcminute angular resolution. A randomization scheme avoids repetition of structures along the line of sight. The angular power spectra of the projected lensing potential and the deflection-angle modulus agree well with semi-analytic estimates on scales between a few arcminutes and about one degree. We find a deficit in power on large scales and an excess in the deflection-angle power on small scales, which we interpret as due to non-linear clustering in the MS. Our map-making procedure is ideally suited for studying lensing of CMB anisotropies, for analyzing cross-correlations with foreground structures, or other secondary CMB anisotropies such as the Rees-Sciama effect. |
| |
|
arXiv:0711.2920 [ps, pdf, other] :
Title: Primordial Non-Gaussianity in Multi-Scalar Inflation
Authors: Shuichiro Yokoyama, Teruaki Suyama, Takahiro Tanaka
Comments: 11 pages, 6 figures
We give a concise formula for the non-Gaussianity of the primordial curvature perturbation generated on super-horizon scales in multi-scalar inflation model without assuming slow-roll conditions. This is an extension of our previous work. Using this formula, we study the generation of non-Gaussianity for the double inflation models in which the slow-roll conditions are temporarily violated after horizon exit, and we show that the non-linear parameter $f_{NL}$ for such models is suppressed by the slow-roll parameters evaluated at the time of horizon exit. |
| |
|
arXiv:0710.5073 [ps, pdf, other] :
Title: Modeling the cosmological co-evolution of supermassive black holes and galaxies: I. BH scaling relations and the AGN luminosity function
Authors: Federico Marulli, Silvia Bonoli, Enzo Branchini, Lauro Moscardini
Comments: 15 pages, 7 figures, MNRAS submitted
We model the cosmological co-evolution of galaxies and their central supermassive black holes (BHs) within a semi-analytical framework developed on the outputs of the Millennium Simulation. This model, described in detail in Croton et al. (2006) and De Lucia & Blaizot (2007), introduces a `radio mode' feedback from Active Galactic Nuclei (AGN) at the centre of X-ray emitting atmospheres in galaxy groups and clusters. Thanks to this mechanism, the model can simultaneously explain: (i) the low observed mass drop-out rate in cooling flows; (ii) the exponential cut-off in the bright end of the galaxy luminosity function; and (iii) the bulge-dominated morphologies and old stellar ages of the most massive galaxies in clusters. This paper is the first of a series in which we investigate how well this model can also reproduce the physical properties of BHs and AGN. Here we analyze the scaling relations, the fundamental plane and the mass function of BHs, and compare them with the most recent observational data. Moreover, we extend the semi-analytic model to follow the evolution of the BH mass accretion and its conversion into radiation, and compare the derived AGN bolometric luminosity function with the observed one. While we find for the most part a very good agreement between predicted and observed BH properties, the semi-analytic model underestimates the number density of luminous AGN at high redshifts, independently of the adopted Eddington factor and accretion efficiency. However, an agreement with the observations is possible within the framework of our model, provided it is assumed that the cold gas fraction accreted by BHs at high redshifts is larger than at low redshifts.. |
| |
|
arXiv:0711.2908 [ps, pdf, other] :
Title: Probing new physics with long-lived charged particles produced by atmospheric and astrophysical neutrinos
Authors: Shin'ichiro Ando, John F. Beacom, Stefano Profumo, David Rainwater
Comments: 25 pages, 6 figures; submitted to JCAP
As suggested by some extensions of the Standard Model of particle physics, dark matter may be a super-weakly interacting lightest stable particle, while the next-to-lightest particle (NLP) is charged and meta-stable. One could test such a possibility with neutrino telescopes, by detecting the charged NLPs produced in high-energy neutrino collisions with Earth matter. We study the production of charged NLPs by both atmospheric and astrophysical neutrinos; only the latter, which is largely uncertain and has not been detected yet, was the focus of previous studies. We compute the resulting fluxes of the charged NLPs, compare those of different origins, and analyze the dependence on the underlying particle physics setup. We point out that even if the astrophysical neutrino flux is very small, atmospheric neutrinos, especially those from the prompt decay of charmed mesons, may provide a detectable NLP flux at neutrino telescopes such as IceCube. We also comment on the flux of charged NLPs expected from proton--nucleon collisions, and show that, for theoretically motivated and phenomenologically viable models, it is typically sub-dominant and below detectable rates. |
| |
|
arXiv:0711.3180 [ps, pdf, other] :
Title: How strong is the evidence for accelerated expansion?
Authors: Marina Seikel, Dominik J Schwarz
Comments: 15 pages, 3 figures
We test the present expansion of the universe using supernova type Ia data without making any assumptions about the matter and energy content of the universe or about the parameterization of the deceleration parameter. We assume the cosmological principle to apply in a strict sense. The result strongly depends on the data set, the light-curve fitting method and the calibration of the absolute magnitude used for the test, indicating strong systematic errors. Nevertheless, in a spatially flat universe there is at least a 5 sigma evidence for acceleration which drops to 1.8 sigma in an open universe. |
| |
|
arXiv:0711.3025 [ps, pdf, other] :
Title: Synoptic studies of seventeen blazars detected in very high energy gamma-rays
Authors: Robert Wagner
Comments: 14 pages, 18 figures, submitted to MNRAS
Since 2002, the number of detected blazars at gamma-ray energies above 100 GeV has far more than doubled. I study 17 blazars currently known to emit E>100 GeV gamma-rays. Their intrinsic energy spectra are reconstructed by removing extragalactic background light attenuation effects. Luminosity and spectral slope in the E>100 GeV region are then compared and correlated among each other, with X-ray, optical, and radio data, and with the estimated black hole masses of the respective host galaxies. In addition, I consider temporal properties of the X-ray and E>100 GeV gamma-ray flux. Key findings of the studies are correlations between the gamma-ray luminosity and the X-ray luminosity, the synchrotron peak location, and the spectral slope in the E>100 GeV region. No correlations of the gamma emission properties with the central black hole masses are found. As a specific application, the study allows to constrain the still undetermined redshift of the blazar PG 1553+113. |
| |
|
arXiv:0711.3129 [ps, pdf, other] :
Title: Spherical collapse in modified gravity with the Birkhoff-theorem
Authors: Bjoern Malte Schaefer, Kazuya Koyama
Comments: 12 pages, 12 figures, 3 tables, submitted to MNRAS
We study structure formation in a phenomenological model of modified gravity which interpolates between LambdaCDM and phenomenological DGP-gravity. Generalisation of spherical collapse by using the Birkhoff-theorem along with the modified growth equation shows that the overdensity for spherical collapse delta_c in these models is significantly lowered compared to LambdaCDM, leading to enhanced number densities of massive clusters and enhanced cluster merging rates. We find that delta_c(z) is well fitted by a function of the form delta_c(z) = a - b\exp(-cz). We examine the sensitivity of PLANCK's and SPT's Sunyaev-Zel'dovich survey to constrain the modified gravity parameterisation and find that these experiments can easily distinguish between models with a cosmological constant and modified gravity, if prior constraints from CMB temperature and polarisation anisotropies are included. |
| |
|
| |
| |
| |
| |
| |
| |
| |
| |
| |
|
