Intrinsic Limits on the Detection of the Anisotropies of the Stochastic Gravitational Wave Background.

For any given network of detectors, and for any given integration time, even in the idealized limit of negligible instrumental noise, the intrinsic time variation of the isotropic component of the stochastic gravitational wave background (SGWB) induces a limit on how accurately the anisotropies in the SGWB can be measured. We show here how this sample limit can be calculated and apply this to three separate configurations of ground-based detectors placed at existing and planned sites. Our results show that in the idealized, best-case scenario, individual multipoles of the anisotropies at ℓ≤8 can only be measured to ∼10^{-5}-10^{-4} level over five years of observation as a fraction of the isotropic component.

HCV point-of-care screening programme and treatment options for people who use drugs in a metropolitan area of Southern Italy.

Background And Aims: People who use drugs (PWUD) represent an active reservoir of HCV infection. The prevalence of chronic HCV infection in PWUD in Italy remains unknown because of the lack of systematic screening. Thanks to direct-acting antiviral agents (DAAs), hepatitis C can now be cured in most patients.

Gravitational-Wave Background Sky Maps from Advanced LIGO O1 Data.

We integrate the publicly available O1 LIGO time-domain data to obtain maximum-likelihood constraints on the gravitational-wave background (GWB) arising from stochastic, persistent signals. Our method produces sky maps of the strain intensity I as a function of direction on the sky at a reference frequency f_{0}. The data are integrated assuming a set of fixed power-law spectra for the signal.

Rotation of galaxies as a signature of cosmic strings in weak lensing surveys.

Vector perturbations sourced by topological defects can generate rotations in the lensing of background galaxies. This is a potential smoking gun for the existence of defects since rotation generates a curl-like component in the weak lensing signal which is not generated by standard density perturbations at linear order. This rotation signal is calculated as generated by cosmic strings.

Instability of anisotropic cosmological solutions supported by vector fields.

Models with vector fields acquiring a nonvanishing vacuum expectation value along one spatial direction have been proposed to sustain a prolonged stage of anisotropic accelerated expansion. Such models have been used for realizations of early time inflation, with a possible relation to the large scale cosmic microwave background anomalies, or of the late time dark energy. We show that, quite generally, the concrete realizations proposed so far are plagued by instabilities (either ghosts or unstable growth of the linearized perturbations) which can be ultimately related to the longitudinal vector polarization present in them.

Anomalous cosmic-microwave-background polarization and gravitational chirality.

We consider the possibility that gravity breaks parity, with left and right-handed gravitons coupling to matter with a different Newton's constant and show that this would affect their zero-point vacuum fluctuations during inflation. Should there be a cosmic background of gravity waves, the effect would translate into anomalous cosmic microwave background polarization. Nonvanishing temperature-magnetic (TB) mode [and electric-magnetic mode] components emerge, revealing interesting experimental targets.

Cosmic microwave background snapshots: pre-WMAP and post-WMAP.

We highlight the remarkable evolution in the cosmic microwave background (CMB) power spectrum C(l) as a function of multipole l over the past few years, and in the cosmological parameters for minimal inflation models derived from it: from anisotropy results before 2000; in 2000 and 2001 from Boomerang, Maxima and the Degree Angular Scale Interferometer (DASI), extending l to approximately 1000; and in 2002 from the Cosmic Background Imager (CBI), Very Small Array (VSA), ARCHEOPS and Arcminute Cosmology Bolometer Array Receiver (ACBAR), extending l to approximately 3000, with more from Boomerang and DASI as well. Pre-WMAP (pre-Wilkinson Microwave Anisotropy Probe) optimal band powers are in good agreement with each other and with the exquisite one-year WMAP results, unveiled in February 2003, which now dominate the l less, similar 600 bands. These CMB experiments significantly increased the case for accelerated expansion in the early Universe (the inflationary paradigm) and at the current epoch (dark energy dominance) when they were combined with "prior" probabilities on the parameters.

Joint cosmic microwave background and weak lensing analysis: constraints on cosmological parameters.

We use cosmic microwave background (CMB) observations together with the red-sequence cluster survey weak lensing results to derive constraints on a range of cosmological parameters. This particular choice of observations is motivated by their robust physical interpretation and complementarity. Our combined analysis, including a weak nucleosynthesis constraint, yields accurate determinations of a number of parameters including the amplitude of fluctuations sigma(8)=0.