BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//CERN//INDICO//EN
BEGIN:VEVENT
SUMMARY:Angled beam expander telescopes for the Michelson beams in third g
 eneration Gravitational Wave Observatories
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4856@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Third generation of Gravitational Wave detectors like the Eins
 tein Telescope or the\nCosmic Explorer will be Michelson interferometers w
 ith Fabry-Perot cavities in the arms\,\nusing mirror test masses with diam
 eter at the limit of technical feasibility. Unlike other\ndetectors\, the 
 Einstein Telescope will have a 60° angle between the arms. Because of its
 \nlarger incidence angle\, at any given beam size\, it would require beam 
 splitters almost double\nin size and much heavier than the 90° case. It i
 s proposed here to install beam expander\ntelescopes with angled mirrors l
 ocated inside the Michelson interferometer between the\nFabry-Perot caviti
 es and the beam splitter. Beyond reducing the beam sizes and the\nbeam spl
 itter to manageable sizes\, the proposed solution allows to bring the opti
 mal\nrecombination angle to 90°. The proposed geometry offers a natural w
 ay to separate the\nbeam splitters of different detectors into individual\
 , smaller and more stable caverns\, thus\nimproving observatory observatio
 n-time efficiency\, to provide needed beam diagnostic\npoints and convenie
 nt degrees of freedom for beam alignment into both the Fabry-Perot\ncaviti
 es and the beam splitter\, as well as to provide a method for maintaining 
 optimal mode\nmatching of the two arms onto the beam splitter without ther
 mal compensation plates.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/255/co
 ntributions/4856/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4856/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Optimization of design parameters for Gravitational Wave detector 
 DECIGO including fundamental noises
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4777@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:The DECi-hertz Interferometer Gravitational-Wave Observatory (
 DECIGO) is a space gravitational wave (GW) detector. DECIGO was originally
  designed to be sensitive enough to observe primordial GW background (PGW)
 . However\, due to the lowered upper limit of the PGW by the Planck observ
 ation\, further improvement of the target sensitivity of DECIGO is require
 d. In the previous studies\, DECIGO’s parameters were optimized to maxim
 ize the signal-to-noise ratio (SNR) of the PGW to quantum noise including 
 the effect of diffraction loss. To simulate the SNR more realistically\, w
 e optimize DECIGO’s parameters considering the GWs from double white dwa
 rfs (DWDs) and the thermal noise of test masses. We consider two cases of 
 the cutoff frequency of GWs from DWDs. In addition\, we consider two kinds
  of thermal noise: thermal noise in a residual gas and internal thermal no
 ise. To investigate how the mirror geometry affects the sensitivity\, we c
 alculate it by changing the mirror mass and thickness. As a result\, we ob
 tained the optimums for the parameters that maximize the SNR that depends 
 on the mirror radius. This result shows that a thick mirror with a large r
 adius gives a good SNR and enables us to optimize the design of DECIGO.\n\
 nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4777/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4777/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Probing dipole radiation with the low-frequency gravitational-wave
  observatories
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4778@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Atom-interferometer gravitational-wave (GW) observatory\, as a
  new design of ground-based GW detector for the near future\, is sensitive
  at a relatively low frequency for GW observations. Taking the proposed at
 om interferometer Zhaoshan Long-baseline Atom Interferometer Gravitation A
 ntenna (ZAIGA)\, and its illustrative upgrade (Z+) as examples\, we invest
 igate how the atom interferometer will complement ground-based laser inter
 ferometers in testing the gravitational dipole radiation from binary neutr
 on star (BNS) mergers. A test of such kind is important for a better under
 standing of the strong equivalence principle laying at the heart of Einste
 in's general relativity. To obtain a statistically sound result\, we sampl
 e BNS systems according to their merger rate and population\, from which w
 e study the expected bounds on the parameterized dipole radiation paramete
 r $B$. Extracting BNS parameters and the dipole radiation from the combina
 tion of ground-based laser interferometers and the atom-interferometer ZAI
 GA/Z+\, we are entitled to obtain tighter bounds on $B$ by a few times to 
 a few orders of magnitude\, compared to ground-based laser interferometers
  alone\, ultimately reaching the levels of $|B| \n\nhttps://indico.icrr.u-
 tokyo.ac.jp/event/255/contributions/4778/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4778/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Prospects for Detecting Exoplanets around Double White Dwarfs with
  LISA and Taiji
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4780@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Recently\, Tamanini & Danielski discussed the possibility of d
 etecting circumbinary exoplanets (CBPs) orbiting double white dwarfs (DWDs
 ) with the Laser Interferometer Space Antenna (LISA). Extending their meth
 ods and criteria\, we discuss the prospects for detecting exoplanets aroun
 d DWDs not only by LISA\, but also by Taiji\, a Chinese space-borne gravit
 ational-wave (GW) mission. We first explore how different binary masses an
 d mass ratios affect the abilities of LISA and Taiji to detect CBPs. Secon
 d\, for certain known detached DWDs with high signal-to-noise ratios\, we 
 quantify the possibility of CBP detections around them. Third\, based on t
 he DWD population obtained from the Mock LISA Data Challenge\, we present 
 basic assessments of the CBP detections in our Galaxy during a 4 yr missio
 n time for LISA and Taiji. We discuss the constraints on the detectable zo
 ne of each system. With the DWD population\, we further inject two differe
 nt planet distributions with an occurrence rate of 50% and constrain the t
 otal detection rates. We briefly discuss the prospects for detecting habit
 able CBPs around DWDs with a simplified model. These results can provide h
 elpful inputs for upcoming exoplanetary projects and help analyze planetar
 y systems after the common envelope phase.\n\nhttps://indico.icrr.u-tokyo.
 ac.jp/event/255/contributions/4780/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4780/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Realistic Detection and Early Warning of Binary Neutron Stars with
  Decihertz Gravitational-wave Observatories
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4781@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:We investigated the detection and localization of binary neutr
 on star (BNS) populations with decihertz gravitational-wave observatories 
 in a realistic detecting strategy\, including real-time observations and e
 arly warnings. Assuming 4 years' operation of B-DECIGO\, we found that the
  detected BNSs can be divided into three categories: (a) sources that merg
 e within 1 year\, which could be localized with an uncertainty of $\\Delta
 \\Omega \\sim 10^{0}$deg$^2$\;  (b) sources that merge in 1-4 years\, whic
 h take up three quarters of the total events and yield the most precise an
 gular resolution with $\\Delta \\Omega\\sim 10^{-2}$deg$^2$ and time-of-me
 rger accuracy with $\\Delta t_c\\sim 10^{-1}$s\; and (c) sources that do n
 ot merge during the 4-yr mission window\, which enable possible early warn
 ings\, with $\\Delta \\Omega\\sim 10^{-1}$deg$^2$ and $\\Delta t_c\\sim 10
 ^{0}$s. Furthermore\, we compared the pros and cons of B-DECIGO with the E
 instein Telescope\, and explored the prospects of detections using 3 other
  decihertz observatories and 4 BNS population models. In realistic observi
 ng scenarios\, we found that decihertz detectors could even provide early-
 warning alerts to a source decades before its merger while their localizat
 ions are still more accurate than ground-based facilities.\n\nhttps://indi
 co.icrr.u-tokyo.ac.jp/event/255/contributions/4781/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4781/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Space gravitational wave antenna DECIGO
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4782@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:DECi-hertz Interferometer Gravitational-wave Observatory (DECI
 GO) is a future Japanese space gravitational-wave antenna with a frequency
  band of 0.1 Hz to 10 Hz. DECIGO aims at detection of primordial gravitati
 onal waves\, which could have been produced during the inflationary period
  right after the birth of the universe. There are many other scientific ob
 jectives of DECIGO\, including the direct measurement of the acceleration 
 of the expansion of the universe\, and reliable and accurate predictions o
 f the timing and locations of neutron star/black hole binary coalescences.
  DECIGO consists of four clusters of observatories placed in the heliocent
 ric orbit. Each cluster consists of three spacecraft\, which form three di
 fferential Fabry-Perot interferometers with an arm length of 1\,000 km. Th
 ree clusters of DECIGO will be placed far from each other\, and the fourth
  cluster will be placed in the same position as one of the three clusters 
 to obtain the correlation signals for the detection of the primordial grav
 itational waves. In this presentation\, we will explain the aimed sciences
 \, the mechanical and optical design\, and the current status of DECIGO.\n
 \nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4782/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4782/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Space GW Antenna B-DECIGO
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4805@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:B-DECIGO is a space gravitational wave antenna mission. While 
 it is a precursor mission of DECIGO\, we can expect fruitful sciences with
  B-DECIGO. One of the most exciting science cases is detection of compact 
 binary system before merger. It will enlarge the possibility of multi-mess
 enger astronomy with electro-magnetic wave observations at the time of mer
 ger. In this presentation \, we will review the science cases and mission 
 concept of B-DECIGO.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contri
 butions/4805/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4805/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Localization of gravitational waves using machine learning
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4807@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:An observation of gravitational waves is a trigger of the mult
 i-messenger search of an astronomical event. A combination of the data fro
 m two or three gravitational wave detectors indicates the location of a so
 urce and low-latency data analysis is key to transferring the information 
 to other detectors sensitive at different wavelengths. In contrast to the 
 current method\, which relies on the matched-filtering technique\, we prop
 osed the use of machine learning that is much faster and possibly more acc
 urate than matched filtering. \nOur machine-learning method is a combinati
 on of the method proposed by Chatterjee *et al.* and a method using the te
 mporal convolutional network.\nWe demonstrate the sky localization of a gr
 avitational-wave source using four detectors: LIGO H1\, LIGO L1\, Virgo\, 
 and KAGRA\, and compare the result in the case without KAGRA to examine th
 e positive influence of having the fourth detector in the global gravitati
 onal-wave network.\n\nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contribu
 tions/4807/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4807/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Practical quantum noise estimate of optical-spring quantum locking
  for space gravitational wave detector DECIGO
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4818@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:The DECi-hertz Interferometer for Gravitational-wave Observato
 ry(DECIGO) aims mainly at the detection of primordial gravitational waves 
 (PGWs) originating from inflation. Recent observations by the Planck satel
 lite and others have lowered the upper limit of PGWs. Thus\, it is necessa
 ry to improve the target sensitivity of DECIGO. A newly proposed method to
  reduce the quantum noise of DECIGO is quantum locking with an optical spr
 ing. In this method\, a short cavity is added to the main cavity\, sharing
  one mirror of both cavities. The error signal in this auxiliary cavity is
  obtained properly in a homodyne detection\, and fed back to the shared mi
 rror to cancel the radiation pressure noise of the main cavity. In our pre
 vious study\, the optimal sensitivity assuming ideal homodyne detection wi
 thout any additional noise was obtained by simulation. In this study\, we 
 investigate a more realistic design\, taking into account the mixture of t
 he vacuum fluctuations incident to the homodyne detection system. In this 
 poster\, we explain the latest results of this investigation\n\nhttps://in
 dico.icrr.u-tokyo.ac.jp/event/255/contributions/4818/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4818/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Sar-Grav Laboratory at the Sos Enattos site\, one of the quiet
 est site in the 2-10 Hz frequency range
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4847@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Einstein Telescope (ET) will be the third generation of gravit
 ational wave interferometer to be built in Europe. One of the sites candid
 ates to host ET is located in Sardinia (Italy)\, near the Sos Enattos mine
 \, where a seismometer’s net already proves the quietness of the site. T
 he Sar-Grav laboratory\, a seed of ET\, aims to host underground experimen
 ts\, cryogenic payloads\, low frequency and cryogenic sensor development t
 hat need low seismic and anthropogenic noise. On the surface there are a h
 angar of about 900 square meters\, an optical laboratory and a control roo
 m\; a 20 tons crane and cleaned rooms are planned to be installed. Undergr
 ound\, an area of 250 square meters and small experimental areas are plann
 ed to be built\, while different stations at different depths are hosting 
 sensors like seismometers and magnetometers. A fundamental physics experim
 ent\, Archimedes\, is under installation in the surface area and will be m
 oved underground in the future.\nThe site will host the test of the prelim
 inary seismic isolation system\, currently under studies \, that will be d
 esigned to improve seismic attenuation in the low frequency region (0.1-10
  Hz) and reduce the frequency of mechanical resonances.\n\nhttps://indico.
 icrr.u-tokyo.ac.jp/event/255/contributions/4847/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4847/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Gravitational wave sources in the low frequency region and their d
 istances
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4849@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Pulsars are expected to be strong sources of low frequency gra
 vitational waves in ground based interferometers. The knowledge of their d
 istances is a key parameter to estimate the gravitational emission. The pu
 lsar distances are usually estimated using dispersion measure. The Gaia da
 ta release provides information on the distance\, kinematic and photometri
 c properties of nearly two billions astronomical sources\, among them some
  pulsars and accreting neutron star systems.\nThe Gaia based distances of 
 some systems relevant for gravitational astronomy will be discussed.\n\nht
 tps://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4849/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4849/
END:VEVENT
BEGIN:VEVENT
SUMMARY:The Current Status of TOrsion-Bar Antenna (TOBA) Experiment
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4850@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Torsion-bar antenna (TOBA) is a ground-based gravity gradiomet
 er proposed for measurement of gravity gradient fluctuations such as gravi
 tational waves and gravity gradient noise. TOBA consists of two perpendicu
 lar torsion pendulum\, and the low mechanical resonant frequency of torsio
 n pendulums enables us to measure gravity gradient of frequencies around 0
 .1 Hz. TOBA aims to achieve the sensitivity 10^(-19) / √Hz at 0.1 Hz. \n
 For the final sensitivity goal we are developing a prototype Phase-III TOB
 A in order to investigate technical issues and establish noise reduction s
 cheme. One of the key topic of Phase-III TOBA is cryogenic suspension syst
 em for the reduction of the thermal noise. Another key point is the readou
 t system with monolithic interferometer. We will show the current situatio
 n of the developments and future upgrade plans for further improvement.\n\
 nhttps://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4850/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4850/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Displacement-noise-free neutron interferometer for gravitational w
 ave detection at low frequencies
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4852@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:Improvement of the sensitivity of gravitational-waves (GWs) de
 tectors at lower frequencies is still challenging on account of displaceme
 nt noise sources\, such as thermal noise\, seismic noise\, and radiation p
 ressure noise. One of the solutions is the displacement-noise-free interfe
 rometer (DFI). At frequencies lower than 1Hz\, however\, the DFI has less 
 sensitivity to GWs because the propagation time of light is much shorter t
 han the period of the GWs. To resolve this problem\, DFI with neutrons ins
 tead of laser\, which is called a neutron DFI\, was proposed. In a neutron
  DFI with neutrons propagating much more slowly than light\, the neutron p
 ropagation time can be comparable to the period of GWs at lower frequencie
 s. This enables us to cancel displacement noise without cancellation of th
 e GW signals. Also\, we proposed a simplification of the detector configur
 ation by taking advantage of the ability to adjust the neutron speeds depe
 nding on the configuration. In our poster\, we discuss the principle of th
 e neutron DFI as well as a plan of the demonstration experiment.\n\nhttps:
 //indico.icrr.u-tokyo.ac.jp/event/255/contributions/4852/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4852/
END:VEVENT
BEGIN:VEVENT
SUMMARY:Current Status of Quantum Locking Experiment for Space Gravitation
 al Wave Antenna DECIGO
DTSTART;VALUE=DATE-TIME:20220524T043000Z
DTEND;VALUE=DATE-TIME:20220524T063000Z
DTSTAMP;VALUE=DATE-TIME:20260412T055632Z
UID:indico-contribution-1184-4853@indico.icrr.u-tokyo.ac.jp
DESCRIPTION:The DECi-hertz Interferometer Gravitational wave Observatory (
 DECIGO) is the future Japanese space mission with 1\,000 km arm cavities. 
 One of the main objectives of DECIGO is the detection of primordial gravit
 ational waves (PGWs) produced in the inflation period. We should improve D
 ECIGO’s target sensitivity\, which is limited by quantum noise\, to enha
 nce the possibility of the detection of PGWs.\n\nThe standard squeezing te
 chniques to reduce the quantum noise are not effective because of the larg
 e diffraction loss in DECIGO due to the long arm length. Therefore\, we pr
 oposed a new method\, quantum locking with an optical spring\, to reduce t
 he quantum noise in a relatively broad frequency band. Quantum locking is 
 the technique\, in which each mirror of the long arm cavity (main cavity) 
 is shared by two short-arm cavities (sub-cavities). Then the sub-cavities 
 control the mirrors’ motion of the main cavity. Interferometer signals o
 btained from the main cavity and the two sub-cavities can be combined to o
 ptimize the sensitivity of DECIGO.\n\nIn parallel with the theoretical ana
 lysis of the technique\, we have been performing the experiment to verify 
 the principle of the theory. In this poster session\, we explain the curre
 nt status of the quantum locking experiment.\n\nhttps://indico.icrr.u-toky
 o.ac.jp/event/255/contributions/4853/
LOCATION:GatherTown and ZOOM
URL:https://indico.icrr.u-tokyo.ac.jp/event/255/contributions/4853/
END:VEVENT
END:VCALENDAR