119246433
ANISOTROPY IN THE MATTER DISTRIBUTION BEYOND THE BARYONIC ACOUSTIC OSCILLATION SCALE
Tracing the cosmic evolution of the baryonic acoustic oscillation (BAO) scale with galaxy two-point correlation functions is currently the most promising approach to detect dark energy at early times. A number of ongoing and future experiments will measure the BAO peak with unprecedented accuracy. We show based on a set of N-body simulations that the matter distribution is anisotropic out to ~150 h –1 Mpc, far beyond the BAO scale of ~100 h –1 Mpc, and discuss implications for the measurement of the BAO. To that purpose we use alignment correlation functions, i.e., cross-correlation functions between high density peaks and the overall matter distribution measured along the orientation of the peaks and perpendicular to it. The correlation function measured along (perpendicular to) the orientation of high density peaks is enhanced (reduced) by a factor of two compared to the conventional correlation function and the location of the BAO peak shifts toward smaller (larger) scales if measured along (perpendicular to) the orientation of the high density peaks. Similar effects are expected to shape observed galaxy correlation functions at BAO scales.
17433293
Are mergers responsible for universal halo properties
N-body simulations of cold dark matter (CDM) have shown that, in this hierarchical structure formation model, dark matter halo properties, such as the density profile, the phase-space density profile, the distribution of axial ratio, the distribution of spin parameter and the distribution of internal specific angular momentum, follow 'universal' laws or distributions. Here, we study the properties of the first generation of haloes in a hot dark matter (HDM) dominated universe, as an example of halo formation through monolithic collapse. We find all these universalities to be present in this case also. Halo density profiles are very well fit by the Navarro, Frenk & White profile over two orders of magnitude in mass. The concentration parameter depends on mass as c α M 0.2 , reversing the dependence found in a hierarchical CDM universe. However, the concentration-formation time relation is similar in the two cases: earlier forming haloes tend to be more concentrated than their later forming counterparts. Halo formation histories are also characterized by two phases in the HDM case: an early phase of rapid accretion followed by slower growth. Furthermore, there is no significant difference between the HDM and CDM cases concerning the statistics of other halo properties: the phase-space density profile; the velocity anisotropy profile; the distribution of shape parameters; the distribution of spin parameter and the distribution of internal specific angular momentum are all similar in the two cases. Only substructure content differs dramatically. These results indicate that mergers do not play a pivotal role in establishing the universalities, thus contradicting models which explain them as consequences of mergers.
17078771
Phase‐space structure in the local dark matter distribution and its signature in direct detection experiments
We study predictions for dark matter phase-space structure near the Sun based on highresolution simulations of six galaxy halos taken from the Aquarius Project. The local DM density distribution is predicted to be remarkably smooth; the density at the Sun differs from the mean over a best-fit ellipsoidal equidensity contour by less than 15% at the 99.9% confidence level. The local velocity distribution is also very smooth, but it differs systematically from a (multivariate) Gaussian distribution. This is not due to th e presence of individual clumps or streams, but to broad features in the velocity modulus and energy distributions that are stable both in space and time and reflect the detailed assembly histo ry of each halo. These features have a significant impact on the signals predicted for WIMP an d axion searches. For example, WIMP recoil rates can deviate by � 10% from those expected from the best-fit multivariate Gaussian models. The axion spectra in our simulations typically peak at lower frequencies than in the case of multivariate Gaussian velocity distribu tions. Also in this case, the spectra show significant imprints of the formation of the halo. Th is implies that once direct DM detection has become routine, features in the detector sign al will allow us to study the dark matter assembly history of the Milky Way. A new field, “dark ma tter astronomy”, will then emerge.
119239648
Substructure lensing: Effects of galaxies, globular clusters and satellite streams
Lensing flux-ratio anomalies have been frequently observed and taken as evidence for the presence of abundant dark matter substructures in lensing galaxies, as predicted by the cold dark matter (CDM) model of cosmogony. In previous work, we examined the cusp-caustic relations of the multiple images of background quasars lensed by galaxy-scale dark matter haloes, using a suite of high-resolution N-body simulations (the Aquarius simulations). In this work, we extend our previous calculations to incorporate both the baryonic and diffuse dark components in lensing haloes. We include in each lensing simulation: (1) a satellite galaxy population derived from a semi-analytic model applied to the Aquarius haloes; (2) an empirical Milky Way globular cluster population and (3) satellite streams (diffuse dark component) identified in the simulations. Accounting for these extra components, we confirm our earlier conclusion that the abundance of intrinsic substructures (dark or bright, bound or diffuse) is not sufficient to explain the observed frequency of cusp-caustic violations in the Cosmic Lens All-Sky Survey (CLASS). We conclude that the observed effect could be the result of the small number statistics of CLASS, or intergalactic haloes along the line of sight acting as additional sources of lensing flux anomalies. Another possibility is that this discrepancy signals a failure of the CDM model.
124150385
Variational Treatment with the Third Order Corrections for SU(2) Lattice Gauge Theory
The variational method in Lagrangian formalism in lattice gauge theory in cumulant expansion is discussed. For SU(2) pure gauge Wi1son model to the third order corrections we show that there is no phase transition in four dimensions, but there exists the first order phase transition in five dimensions at βC=0.838 in agreement with the Monte Carlo results. The physical meaning of higher order corrections is discussed.
119516023
Lattice SU(2) gauge-Higgs system in analytic treatment
The phase diagrams of SU(2) gauge-Higgs model with Higgs field of arbitrary length in the fundamental representation in four and five dimension are studied analytically. A method for determining phase transition lines is proposed. All qualitative features of the phase diagram obtained by Monte Carlo simulations are obtained analytically, and the order of phase transitions can be determined definitely.
119220410
Measurement of the cross section and angular correlations for associated production of a Z boson with b hadrons in pp collisions at $ \sqrt{s} $ = 7 TeV
A bstractA study of proton-proton collisions in which two b hadrons are produced in association with a Z boson is reported. The collisions were recorded at a centre-of-mass energy of 7 TeVwith the CMS detector at the LHC, for an integrated luminosity of 5.2 fb−1. The b hadrons are identified by means of displaced secondary vertices, without the use of reconstructed jets, permitting the study of b-hadron pair production at small angular separation. Differential cross sections are presented as a function of the angular separation of the b hadrons and the Z boson. In addition, inclusive measurements are presented. For both the inclusive and differential studies, different ranges of Z boson momentum are considered, and each measurement is compared to the predictions from different event generators at leading-order and next-to-leading-order accuracy.

18867535
Clustering of Lyman alpha emitters at z ~ 4.5
We present the clustering properties of 151 Lyα-emitting galaxies at z ≈ 4.5 selected from the Large Area Lyman Alpha (LALA) survey. Our catalog covers an area of 36' × 36' observed with five narrowband filters. We assume that the angular correlation function w(θ) is well represented by a power law Awθ-β with slope β = 0.8, and we find Aw = 6.73 ± 1.80. We then calculate the correlation length r0 of the real-space two-point correlation function ξ(r) = (r/r0)-1.8 from Aw through the Limber transformation, assuming a flat, Λ-dominated universe. Neglecting contamination, we find r0 = 3.20 ± 0.42 h-1 Mpc. Taking into account a possible 28% contamination by randomly distributed sources, we find r0 = 4.61 ± 0.6 h-1 Mpc. We compare these results with the expectations for the clustering of dark matter halos at this redshift in a cold dark matter model, and find that the measured clustering strength can be reproduced if these objects reside in halos with a minimum mass of (1-2) × 1011 h-1 M☉. Our estimated correlation length implies a bias of b ~ 3.7, similar to that of Lyman break galaxies (LBGs) at z ~ 3.8-4.9. However, Lyα emitters are a factor of ~2-16 rarer than LBGs with a similar bias value and implied host halo mass. Therefore, one plausible scenario seems to be that Lyα emitters occupy host halos of roughly the same mass as LBGs, but shine with a relatively low duty cycle of 6%-50%.
209842367
Alignment of the CMS tracker with LHC and cosmic ray data
© CERN 2014 for the benefit of the CMS collaboration, published under the terms of the Creative Commons Attribution 3.0 License by IOP Publishing Ltd and Sissa Medialab srl. Any further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation and DOI.
14129862
Extended Multiwavelength Fuzz around Red Quasars: The Observational Appearance of Radiative Feedback in Action
Red quasars are a population characterized by significant extinction in UV, which could be explained by absorption of dusty gas on a scale of a few kpc. We show that the enhanced radiation pressure drives the dusty gas to supersonically expand and produces shocks. The shocks energize electrons to be relativistic via the first Fermi acceleration. As a balance of shock acceleration and synchrotron emission and inverse Compton scattering, the maximum Lorentz factor of the electrons reaches ~106. The shocked interstellar medium appears as extended multiwavelength fuzz, in which synchrotron emission from the electrons peaks at near-infrared or UV bands and inverse Compton scattering around 1.0 GeV-0.1 TeV. Future multiwavelength images of the fuzz would provide new clues to study the details of radiative feedback if red quasars are a certain phase in the evolutionary chains of galaxies.
118833844
COSMOLOGICAL EVOLUTION OF SUPERMASSIVE BLACK HOLES. I. MASS FUNCTION AT 0 < z ≲ 2
We present the mass function of supermassive black holes (SMBHs) over the redshift range z = 0-2, using the latest deep luminosity and mass functions of field galaxies to constrain the masses of their spheroids, which we relate to SMBH mass through the empirical correlation between SMBH and spheroid mass (the M •-M sph relation). In addition to luminosity fading of the stellar content of the spheroids, we carefully consider the variation of the bulge-to-total luminosity ratio of the galaxy populations and the M •/M sph ratio, which, according to numerous recent studies, evolves rapidly with redshift. The SMBH mass functions derived from the galaxy luminosity and mass functions show very good agreement, both in shape and in normalization. The resultant SMBH mass function and integrated mass density for the local epoch (z ≈ 0) match well those derived independently by other studies. Consistent with other evidence for cosmic downsizing, the upper end of the mass function remains roughly constant since z ≈ 2, while the space density of lower mass black holes undergoes strong evolution. We carefully assess the impact of various sources of uncertainties on our calculations. A companion paper uses the mass function derived in this work to determine the radiative efficiency of black hole accretion and constraints that can be imposed on the cosmological evolution of black hole spin.