scholarly journals KAGRA underground environment and lessons for the Einstein Telescope

2021 ◽  
Vol 104 (4) ◽  
Author(s):  
Francesca Badaracco ◽  
Jan Harms ◽  
Camilla De Rossi ◽  
Irene Fiori ◽  
Kouseki Miyo ◽  
...  
Keyword(s):  
2021 ◽  
Vol 81 (1) ◽  
Author(s):  
Xiaogang Zheng ◽  
Shuo Cao ◽  
Yuting Liu ◽  
Marek Biesiada ◽  
Tonghua Liu ◽  
...  

AbstractIn order to estimate cosmic curvature from cosmological probes like standard candles, one has to measure the luminosity distance $$D_L(z)$$ D L ( z ) , its derivative with respect to redshift $$D'_L(z)$$ D L ′ ( z ) and the expansion rate H(z) at the same redshift. In this paper, we study how such idea could be implemented with future generation of space-based DECi-hertz Interferometer Gravitational-wave Observatory (DECIGO), in combination with cosmic chronometers providing cosmology-independent H(z) data. Our results show that for the Hubble diagram of simulated DECIGO data acting as a new type of standard siren, it would be able to constrain cosmic curvature with the precision of $$\varDelta \varOmega _k= 0.09$$ Δ Ω k = 0.09 with the currently available sample of 31 measurements of Hubble parameters. In the framework of the third generation ground-based gravitational wave detectors, the spatial curvature is constrained to be $$\varDelta \varOmega _k= 0.13$$ Δ Ω k = 0.13 for Einstein Telescope (ET). More interestingly, compared to other approaches aiming for model-independent estimations of spatial curvature, our analysis also achieve the reconstruction of the evolution of $$\varOmega _k(z)$$ Ω k ( z ) , in the framework of a model-independent method of Gaussian processes (GP) without assuming a specific form. Therefore, one can expect that the newly emerged gravitational wave astronomy can become useful in local measurements of cosmic curvature using distant sources.


Universe ◽  
2020 ◽  
Vol 6 (1) ◽  
pp. 10
Author(s):  
Edit Fenyvesi ◽  
József Molnár ◽  
Sándor Czellár

Infrasound and seismic waves are supposed to be the main contributors to the gravity-gradient noise (Newtonian noise) of the third-generation subterranean gravitational wave detectors. This noise will limit the sensitivity of the instrument at frequencies below 20 Hz. Investigation of its origin and the possible methods of mitigation have top priority during the designing period of the detectors. Therefore, long-term site characterizing measurements are needed at several subterranean sites. However, at some sites, mining activities can occur. These activities can cause sudden changes (transients) in the measured signal, and increase the continuous background noise, too. We have developed an algorithm based on discrete Haar transform to find these transients in the infrasound signal. We found that eliminating the transients decreases the variation of the noise spectra, and therefore results a more accurate characterization of the continuous background noise. We carried out experiments for controlling the continuous noise. Machines operating at the mine were turned on and off systematically in order to see their effect on the noise spectra. These experiments showed that the main contributor of the continuous noise is the ventilation system of the mine. We also estimated the contribution of infrasound Newtonian noise at MGGL to the strain noise of a subterranean GW detector similar to Einstein Telescope.


2020 ◽  
Vol 497 (1) ◽  
pp. 204-209 ◽  
Author(s):  
Hai Yu ◽  
Pengjie Zhang ◽  
Fa-Yin Wang

ABSTRACT Standard siren cosmology of gravitational wave (GW) merger events relies on the identification of host galaxies and their redshifts. But this can be highly challenging due to numerous candidates of galaxies in the GW localization area. We point out that the number of candidates can be reduced by orders of magnitude for strongly lensed GW events, due to extra observational constraints. For the next-generation GW detectors like Einstein Telescope (ET), we estimate that this number is usually significantly less than one, as long as the GW localization uncertainty is better than $\sim 10\, \rm deg^2$. This implies that the unique identification of the host galaxy of lensed GW event detected by ET and Cosmic Explorer (CE) is possible. This provides us a promising opportunity to measure the redshift of the GW event and facilitate the standard siren cosmology. We also discuss its potential applications in understanding the evolution process and environment of the GW event.


2020 ◽  
Vol 495 (2) ◽  
pp. 2475-2495 ◽  
Author(s):  
Boyuan Liu ◽  
Volker Bromm

ABSTRACT We use cosmological hydrodynamic simulations to study the gravitational wave (GW) signals from high-redshift binary black holes (BBHs) formed by dynamical capture (ex situ formation channel). We in particular focus on black holes (BHs) originating from the first generation of massive, metal-poor, so-called Population III (Pop III) stars. An alternative (in situ) formation pathway arises in Pop III binary stars whose GWligi signature has been intensively studied. In our optimistic model, we predict a local GW event rate density for ex situ BBHs (formed at z > 4) of ∼0.04 yr−1 Gpc−3. This is comparable to or even higher than the conservative predictions of the rate density for in situ BBHs ∼0.01–0.1 yr−1 Gpc−3, indicating that the ex situ formation channel may be as important as the in situ one for producing GW events. We also evaluate the detectability of our simulated GW events for selected planned GW instruments, such as the Einstein Telescope (ET). For instance, we find the all-sky detection rate with signal-to-noise ratios above 10 to be ${\lesssim} 100\, \rm {yr^{-1}}$ for the xylophone configuration of ET. However, our results are highly sensitive to the subgrid models for BBH identification and evolution, such that the GW event efficiency (rate) is reduced by a factor of 4 (20) in the pessimistic case. The ex situ channel of Pop III BBHs deserves further investigation with better modelling of the environments around Pop III-seeded BHs.


2020 ◽  
Vol 2020 (05) ◽  
pp. 021-021 ◽  
Author(s):  
Riis R.A. Bachega ◽  
André A. Costa ◽  
E. Abdalla ◽  
K.S.F. Fornazier

2020 ◽  
Vol 3 (1) ◽  
Author(s):  
Juan Calderon Bustillo ◽  
Christopher Evans ◽  
James A. Clark ◽  
Grace Kim ◽  
Pablo Laguna ◽  
...  

Abstract The merger of a binary black hole gives birth to a highly distorted final black hole. The gravitational radiation emitted as this black hole relaxes presents us with the unique opportunity to probe extreme gravity and its connection with the dynamics of the black hole horizon. Using numerical relativity simulations, we demonstrate a connection between a concrete observable feature in the gravitational waves and geometrical features on the dynamical apparent horizon of the final black hole. Specifically, we show how the line-of-sight passage of a “cusp”-like defect on the horizon of the final black hole correlates with “chirp”-like frequency peaks in the post-merger gravitational-waves. These post-merger chirps should be observed and analyzed as the sensitivity of LIGO and Virgo increase and as future generation detectors, such as LISA and the Einstein Telescope, become operational.


Physics World ◽  
2011 ◽  
Vol 24 (06) ◽  
pp. 13-13
Author(s):  
Michael Banks
Keyword(s):  

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