scholarly journals The current status of contribution activities in Japan for LISA

2020 ◽  
Author(s):  
Kiwamu Izumi ◽  
Norichika Sago ◽  
Tomotada Akutsu ◽  
Masaki Ando ◽  
Ryuichi Fujita ◽  
...  
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
International Collaboration ◽  
Supermassive Black Holes ◽  
Wave Frequency ◽  
Current Status ◽  
Theoretical Studies ◽  
Mass Ratio ◽  
Compact Binaries ◽  
Frequency Window

Abstract LISA is a space gravitational-wave mission that will open the unexplored gravitational-wave frequency window at around millihertz, shedding light on the study of supermassive black holes and the nature of gravity. The LISA project has been propelled by international collaboration in order to maximize the scientific outcome. With the aim of making scientifically important contributions to LISA, instrument and science groups were newly formed in Japan. This article summarizes the current status of the contribution activities conducted by each group to date, highlighting a few selected topics including the development of photoreceivers and theoretical studies on compact binaries and extreme mass ratio inspirals.

scholarly journals Gravitational wave detection in space

2016 ◽  
Vol 25 (14) ◽  
pp. 1630001 ◽  
Author(s):  
Wei-Tou Ni
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Frequency Band ◽  
Low Frequency ◽  
Big Bang ◽  
Mass Ratio ◽  
Intermediate Mass ◽  
Compact Binaries ◽  
Laser Interferometer Space Antenna ◽  
Deployment Time

Gravitational Wave (GW) detection in space is aimed at low frequency band (100[Formula: see text]nHz–100[Formula: see text]mHz) and middle frequency band (100[Formula: see text]mHz–10[Formula: see text]Hz). The science goals are the detection of GWs from (i) Supermassive Black Holes; (ii) Extreme-Mass-Ratio Black Hole Inspirals; (iii) Intermediate-Mass Black Holes; (iv) Galactic Compact Binaries and (v) Relic GW Background. In this paper, we present an overview on the sensitivity, orbit design, basic orbit configuration, angular resolution, orbit optimization, deployment, time-delay interferometry (TDI) and payload concept of the current proposed GW detectors in space under study. The detector proposals under study have arm length ranging from 1000[Formula: see text]km to [Formula: see text][Formula: see text]km (8.6[Formula: see text]AU) including (a) Solar orbiting detectors — (ASTROD Astrodynamical Space Test of Relativity using Optical Devices (ASTROD-GW) optimized for GW detection), Big Bang Observer (BBO), DECi-hertz Interferometer GW Observatory (DECIGO), evolved LISA (e-LISA), Laser Interferometer Space Antenna (LISA), other LISA-type detectors such as ALIA, TAIJI etc. (in Earthlike solar orbits), and Super-ASTROD (in Jupiterlike solar orbits); and (b) Earth orbiting detectors — ASTROD-EM/LAGRANGE, GADFLI/GEOGRAWI/g-LISA, OMEGA and TIANQIN.

scholarly journals Gravitational Wave (GW) Classification, Space GW Detection Sensitivities and AMIGO (Astrodynamical Middle-frequency Interferometric GW Observatory)

2018 ◽  
Vol 168 ◽  
pp. 01004 ◽  
Author(s):  
Wei-Tou Ni
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Gravitational Wave ◽  
Frequency Band ◽  
Low Frequency ◽  
Spectral Classification ◽  
Mass Ratio ◽  
Intermediate Mass ◽  
Black Hole Binaries ◽  
Compact Binaries

After first reviewing the gravitational wave (GW) spectral classification. we discuss the sensitivities of GW detection in space aimed at low frequency band (100 nHz–100 mHz) and middle frequency band (100 mHz–10 Hz). The science goals are to detect GWs from (i) Supermassive Black Holes; (ii) Extreme-Mass-Ratio Black Hole Inspirals; (iii) Intermediate-Mass Black Holes; (iv) Galactic Compact Binaries; (v) Stellar-Size Black Hole Binaries; and (vi) Relic GW Background. The detector proposals have arm length ranging from 100 km to 1.35×109 km (9 AU) including (a) Solar orbiting detectors and (b) Earth orbiting detectors. We discuss especially the sensitivities in the frequency band 0.1-10 μHz and the middle frequency band (0.1 Hz–10 Hz). We propose and discuss AMIGO as an Astrodynamical Middlefrequency Interferometric GW Observatory.

AGN and the necessity of feedback

2005 ◽  
Vol 363 (1828) ◽  
pp. 695-704 ◽  
Author(s):  
Andrew J. Benson
Keyword(s):  
Black Holes ◽  
Star Formation ◽  
Galaxy Formation ◽  
Supermassive Black Holes ◽  
Observational Evidence ◽  
Theoretical Studies ◽  
Feedback Process ◽  
Low Mass

There is now good observational evidence that some type of feedback process must operate within galaxies. Such a process has long been thought to exist on the basis of theoretical studies of galaxy formation. This feedback is responsible for regulating the rate of star formation and thereby preventing the formation of an overabundance of low–mass galaxies. There is gathering evidence that this feedback process must somehow involve the supermassive black holes thought to dwell in the centres of galaxies.

scholarly journals Virgo and Gravitational-Wave Computing in Europe

2020 ◽  
Vol 245 ◽  
pp. 07050
Author(s):  
Stefano Bagnasco
Keyword(s):  
Gravitational Wave ◽  
Current Status ◽  
Low Latency ◽  
Observational Period ◽  
Compact Binaries ◽  
The Third ◽  
Compact Binary ◽  
Continuous Waves ◽  
The Us ◽  
Wave Event

Advanced Virgo is an interferometer for the detection of gravitational waves at the European Gravitational Observatory in Italy. Along with the two Advanced LIGO interferometers in the US, Advanced Virgo is being used to collect data from astrophysical sources such as compact binary coalescences and is currently running the third observational period, collecting gravitational wave event candidates at a rate of more than once per week. Data from the interferometer are processed by running search pipelines for several expected signals, from coalescing compact binaries to continuous waves and burst events. Furthermore, detector characterisation studies are run. Some of the processing needs to be done with low latency, to be able to provide triggers for other observatories and make multi-messenger observations possible. Deep searches are run offline on external computing centres. Thus, data needs also to be reliably and promptly distributed from the EGO site to computer centres in Europe and the US for further analysis and archival storage. Two of the defining characteristics of Virgo computing are the heterogeneity of the activities and the need to interoperate with LIGO. A very wide array of analysis pipelines differing in scientific target, implementation details and running environment assumptions have to be allowed to run ubiquitously and uniformly on dedicated resources and, in perspective, on heterogeneous infrastructures. The current status, possible strategies and outlook of Virgo computing are discussed.

The stellar graveyard

2019 ◽  
pp. 177-206
Author(s):  
Nils Andersson
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Neutron Stars ◽  
Gravitational Wave ◽  
Stellar Evolution ◽  
White Dwarfs ◽  
Supermassive Black Holes ◽  
Compact Objects ◽  
Fermi Gases ◽  
The 1950S

This chapter introduces the different classes of compact objects—white dwarfs, neutron stars, and black holes—that are relevant for gravitational-wave astronomy. The ideas are placed in the context of developing an understanding of the likely endpoint(s) of stellar evolution. Key ideas like Fermi gases and the Chandrasekhar mass are discussed, as is the emergence of general relativity as a cornerstone of astrophysics in the 1950s. Issues associated with different formation channels for, in particular, black holes are considered. The chapter ends with a discussion of the supermassive black holes that are found at the centre of galaxies.

scholarly journals ASTROD-GW: OVERVIEW AND PROGRESS

2013 ◽  
Vol 22 (01) ◽  
pp. 1341004 ◽  
Author(s):  
WEI-TOU NI
Keyword(s):  
Black Holes ◽  
Low Frequency ◽  
Detection Sensitivity ◽  
Mass Ratio ◽  
Lagrange Points ◽  
Compact Binaries ◽  
Simulation And Optimization ◽  
Spacecraft Formation ◽  
Length Changes ◽  
Spacecraft Orbits

In this paper, we present an overview of Astrodynamical Space Test of Relativity using Optical Devices (ASTROD-GW) optimized for Gravitational Wave (GW) detection mission concept and its studies. ASTROD-GW is an optimization of ASTROD which focuses on low frequency GW detection. The detection sensitivity is shifted by a factor of 260 (52) towards longer wavelengths compared with that of NGO/eLISA (LISA). The mission consists of three spacecraft, each of which orbits near one of the Sun–Earth Lagrange points (L3, L4 and L5), such that the array forms an almost equilateral triangle. The three spacecraft range interferometrically with one another with an arm length of about 260 million kilometers. The orbits have been optimized resulting in arm length changes of less than ± 0.00015 AU or, fractionally, less than ±10-4 in 20 years, and relative Doppler velocities of the three spacecraft of less than ±3 m/s. In this paper, we present an overview of the mission covering: the scientific aims, the sensitivity spectrum, the basic orbit configuration, the simulation and optimization of the spacecraft orbits, the deployment of ASTROD-GW formation, Time Delay Interferometry (TDI) and the payload. The science goals are the detection of GWs from (i) Supermassive Black Holes; (ii) Extreme-Mass-Ratio Black Hole Inspirals; (iii) Intermediate-Mass Black Holes; (iv) Galactic Compact Binaries and (v) Relic GW Background. For the purposes of primordial GW detection, a six spacecraft formation would be needed to enable the correlated detection of stochastic GWs. A brief discussion of the six spacecraft orbit optimization is also presented.

GRAVITATIONAL WAVEFORMS FOR BINARY BLACK HOLES

2011 ◽  
Vol 20 (10) ◽  
pp. 2081-2086
Author(s):  
BALA R IYER
Keyword(s):  
Black Holes ◽  
Gravitational Wave ◽  
Numerical Relativity ◽  
Current Status ◽  
Next Generation ◽  
Binary Black Holes ◽  
Gravitational Wave Detectors ◽  
Body Method

Over the last decade gravitational waveforms of binary black holes have been investigated using a variety of approaches like the Multipolar post-Minkowskian formalism, Numerical Relativity and the Effective-One-Body method. We review these complementary approaches and summarize the current status of these investigations of relevance to construct the best templates for the next generation Advanced gravitational wave detectors.

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