Searching for parity violation with the LIGO-Virgo-KAGRA network

A stochastic gravitational wave background is expected to emerge from the superposition of numerous gravitational wave sources of both astrophysical and cosmological origin. A number of cosmological models can have a parity violation, resulting in the generation of circularly polarised gravitational waves. We present a method to search for parity violation in the gravitational wave data. We first apply this method to the most recent, third, LIGO-Virgo observing run. We then investigate the constraining power of future A+ LIGO-Virgo detectors, including KAGRA to the network, for a gravitational wave background generated by early universe cosmological turbulence.Comment: 6 pages, 5 figure

Implications for first-order cosmological phase transitions from the third LIGO-Virgo observing run

We place constrains on the normalised energy density in gravitational waves from first-order strong phase transitions using data from Advanced LIGO and Virgo's first, second and third observing runs. First, adopting a broken power law model, we place $95 \%$ confidence level upper limits simultaneously on the gravitational-wave energy density at 25 Hz from unresolved compact binary mergers, $\Omega_{\rm cbc} < 5.9 \times 10^{-9}$, and strong first-order phase transitions, $\Omega_{\rm bpl} < 2.8 \times 10^{-9}$. We then consider two more complex phenomenological models, limiting at 25 Hz the gravitational-wave background due to bubble collisions to $\Omega_{\rm pt} < 5.0\times 10^{-9}$ and the background due to sound waves to $\Omega_{\rm pt} < 5.8\times10^{-9}$ at $95 \%$ confidence level for temperatures above $10^8$GeV.Comment: 7 pages, 3 figure

Detection of humoral and cellular immune response to anti-SARS-CoV-2 BNT162b2 vaccine in breastfeeding women and naïve and previously infected individuals

This study explored humoral and cellular responses to anti-SARS-CoV-2 BNT162b2 mRNA vaccine in breastfeeding women and naïve and seropositive individuals in the first six months after vaccination.Sixty-one volunteers vaccinated with two doses of the BNT162b2 mRNA vaccine were enrolled in the study. In-house developed ELISA was used for the quantification of SARS-CoV-2 RBD-specific antibodies. Cell surface marker expression and intracellular IFN-γ analysis were carried out by flow cytometry. The concentrations of IFN-γ, IL-6 and TNF were determined by ELISA. A significant rise in anti-RBD IgG antibody levels was observed 14 days after the first vaccine dose (p < 0.0001) in serum and milk. The expression of CD28 on CD4+ T cells was significantly higher compared to baseline (p < 0.05). There was a significant increase (p ≤ 0.05) in B cell lymphocyte subset after revaccination, and increased percentage of CD80+ B cells. The expression of IFN-γ in peripheral blood lymphocytes, CD3+ T cells and serum was significantly increased (p < 0.05). No significant difference in immune response was observed between breastfeeding women and other study participants. The anti-SARS-CoV-2 BNT162b2 mRNA vaccine-induced measurable and durable immune response in breastfeeding women and in naïve and previously infected individuals

Science with the Einstein Telescope: a comparison of different designs

The Einstein Telescope (ET), the European project for a third-generation gravitational-wave detector, has a reference configuration based on a triangular shape consisting of three nested detectors with 10 km arms, where in each arm there is a `xylophone' configuration made of an interferometer tuned toward high frequencies, and an interferometer tuned toward low frequencies and working at cryogenic temperature. Here, we examine the scientific perspectives under possible variations of this reference design. We perform a detailed evaluation of the science case for a single triangular geometry observatory, and we compare it with the results obtained for a network of two L-shaped detectors (either parallel or misaligned) located in Europe, considering different choices of arm-length for both the triangle and the 2L geometries. We also study how the science output changes in the absence of the low-frequency instrument, both for the triangle and the 2L configurations. We examine a broad class of simple `metrics' that quantify the science output, related to compact binary coalescences, multi-messenger astronomy and stochastic backgrounds, and we then examine the impact of different detector designs on a more specific set of scientific objectives.Comment: 197 pages, 72 figure

Footprints of population III stars in the gravitational-wave background

We investigate detection prospects of the gravitational-wave background (GWB) that originates from the merging of compact objects formed by the collapse of population III stars. Younger population I/II stars lead to a GWB in the LIGO/Virgo frequency band at the inspiral phase, while population III stars would likely show up at the later merger and ringdown phases. We show that, using a network of third-generation detectors, we may be able to separate a population I/II signal from a population III one, provided we can subtract individual coalescence events. A detection of a population III GWB could reveal important information, such as the average redshifted total mass

Simultaneous estimation of astrophysical and cosmological stochastic gravitational-wave backgrounds with terrestrial detectors

International audienceThe recent Advanced LIGO and Advanced Virgo joint observing runs have not claimed a stochastic gravitational-wave background detection, but one expects this to change as the sensitivity of the detectors improves. The challenge of claiming a true detection will be immediately succeeded by the difficulty of relating the signal to the sources that contribute to it. In this paper, we consider backgrounds that comprise compact binary coalescences and additional cosmological sources, and we set simultaneous upper limits on these backgrounds. We find that the Advanced LIGO/Advanced Virgo network, operating at design sensitivity, will not allow for separation of the sources we consider. Third-generation detectors, sensitive to most individual compact binary mergers, can reduce the astrophysical signal via subtraction of individual sources, and potentially reveal a cosmological background. Our Bayesian analysis shows that, assuming a detector network containing Cosmic Explorer and Einstein Telescope and reasonable levels of individual source subtraction, we can detect cosmological signals ΩCS(25  Hz)=4.5×10−13 for cosmic strings, and ΩBPL(25  Hz)=2.2×10−13 for a broken power-law model of an early Universe phase transition