No Arabic abstract
Einstein gravitational-wave Telescope (ET) is a design study funded by the European Commission to explore the technological challenges of and scientific benefits from building a third generation gravitational wave detector. The three-year study, which concluded earlier this year, has formulated the conceptual design of an observatory that can support the implementation of new technology for the next two to three decades. The goal of this talk is to introduce the audience to the overall aims and objectives of the project and to enumerate ETs potential to influence our understanding of fundamental physics, astrophysics and cosmology.
The advanced interferometer network will herald a new era in observational astronomy. There is a very strong science case to go beyond the advanced detector network and build detectors that operate in a frequency range from 1 Hz-10 kHz, with sensitivity a factor ten better in amplitude. Such detectors will be able to probe a range of topics in nuclear physics, astronomy, cosmology and fundamental physics, providing insights into many unsolved problems in these areas.
Gravitational waves (GWs) are expected to play a crucial role in the development of multimessenger astrophysics. The combination of GW observations with other astrophysical triggers, such as from gamma-ray and X-ray satellites, optical/radio telescopes, and neutrino detectors allows us to decipher science that would otherwise be inaccessible. In this paper, we provide a broad review from the multimessenger perspective of the science reach offered by the third generation interferometric GW detectors and by the Einstein Telescope (ET) in particular. We focus on cosmic transients, and base our estimates on the results obtained by ETs predecessors GEO, LIGO, and Virgo.
Einstein Telescope (ET) is a possible third generation ground-based gravitational wave observatory for which a design study is currently being carried out. A brief (and non-exhaustive) overview is given of ETs projected capabilities regarding astrophysics and cosmology through observations of inspiraling and coalescing compact binaries. In particular, ET would give us unprecedented insight into the mass function of neutron stars and black holes, the internal structure of neutron stars, the evolution of coalescence rates over cosmological timescales, and the geometry and dynamics of the Universe as a whole.
Einstein Telescope (ET) is conceived to be a third generation gravitational-wave observatory. Its amplitude sensitivity would be a factor ten better than advanced LIGO and Virgo and it could also extend the low-frequency sensitivity down to 1--3 Hz, compared to the 10--20 Hz of advanced detectors. Such an observatory will have the potential to observe a variety of different GW sources, including compact binary systems at cosmological distances. ETs expected reach for binary neutron star (BNS) coalescences is out to redshift $zsimeq 2$ and the rate of detectable BNS coalescences could be as high as one every few tens or hundreds of seconds, each lasting up to several days. %in the sensitive frequency band of ET. With such a signal-rich environment, a key question in data analysis is whether overlapping signals can be discriminated. In this paper we simulate the GW signals from a cosmological population of BNS and ask the following questions: Does this population create a confusion background that limits ETs ability to detect foreground sources? How efficient are current algorithms in discriminating overlapping BNS signals? Is it possible to discern the presence of a population of signals in the data by cross-correlating data from different detectors in the ET observatory? We find that algorithms currently used to analyze LIGO and Virgo data are already powerful enough to detect the sources expected in ET, but new algorithms are required to fully exploit ET data.
We numerically construct a symmetric wormhole solution in pure Einstein gravity supported by a massive $3$-form field with a potential that contains a quartic self-interaction term. The wormhole spacetimes have only a single throat and they are everywhere regular and asymptotically flat. Furthermore, their mass and throat circumference increase almost linearly as the coefficient of the quartic self-interaction term $Lambda$ increases. The amount of violation of the null energy condition (NEC) is proportional to the magnitude of $3$-form, thus the NEC is less violated as $Lambda$ increases, since the magnitude of $3$-form decreases with $Lambda$. In addition, we investigate the geodesics of particles moving around the wormhole. The unstable photon orbit is located at the throat. We also find that the wormhole can cast a shadow whose apparent size is smaller than that cast by the Schwarzschild black hole, but reduces to it when $Lambda$ acquires a large value. The behavior of the innermost stable circular orbit around this wormhole is also discussed. The results of this paper hint toward the possibility that the 3-form wormholes could be potential black hole mimickers, as long as $Lambda$ is sufficiently large, precisely when NEC is weakly violated.