Latecomers benefits S. Haino Latecomers benefits Latecomers - - PowerPoint PPT Presentation

Latecomer’s benefits

• S. Haino

Latecomer’s benefits

Latecomer’s benefits → 後出しジャンケン

Current situation and foreseen scenario

• O1: LIGO already detected 2(+1) BH-BH sources
• O2: LIGO will detect x BH-BH (and maybe NS-NS/BH ?)

Virgo will join for more accurate localization

• O3: L-V will detect y BH-BH (and maybe NS-NS/BH ?)
• KAGRA should join eventually

but the sensitivities of L-V would be far advanced …

SH’s personal concerns and ideas

• LIGO’s first GW detection marked the end of “GW search era”

Now we entered a new era of GW physics/astronomy

• Are BNS/BBH ranges the best performance indicator ?
• Derived from integrating over wide frequency bands
• In general, optimizing BNS/BBH range will make

the sensitivities in high frequency worse

• Can we tune the detector based on the physics targets ?
• This is a standard approach in e.g. High Energy (HEP) projects

KAGRA will have a choice

By the time KAGRA will join the GW network, we will see … Still BH-BH only or any NS-NS/BH detected ? Any sign of new physics in BH-BH ? New physics in … ? Any sign of EM counterparts ? Any sign of new GW sources ? Low frequency target

• Mid. frequency target

High frequency target Inspiral Merger/ QNM Yes: Focus on Localization BH-BH only NS also

• r else …

Yes ! No Any sign

• f HMNS ?

KAGRA’s technological advantages in low, mid. and high frequencies

• [Low] Underground

→ Low seismic noise and enable 2-story tall suspension → Feasible to optimize the sensitivity at low frequency

• [Mid./High] Cryogenic sapphire mirror

→ Low thermal noise, → High thermal conductivity, negligible thermal lensing

• [High] Sapphire’s high young’s modulus

→ Less parametric instability → Better calibration accuracy (Pcal) However, because of the quantum limits, improving in both low and high frequency will need new challenges

Low frequency tuning

• Team brown
• Maximize KAGRA’s advantages
• Underground → Low seismic noise and tall suspension
• Cryogenic → Low thermal noise
• Low laser power → Easy to keep the mirror cooled
• Concerns: various noise sources

High frequency tuning

• High power laser needed

→ Shorter and thicker mirror suspension needed → Increase suspension and thermal noise in low/mid frequency → Increase radiation pressure noise

• Dominated by fundamental (quantum) noise
• There are still KAGRA’s advantages
• Cryogenic sapphire

→ Small thermal lensing, Parametric instability

Then G2.5 and G3 ?

• LIGO → L+ → Voyager → CE
• Virgo → V+ → ET
• KAGRA → ?

Again KAGRA+ will have a choice in technological aspects

By the time KAGRA is online, advanced technologies may have some developments/prospects on the feasibilities of :

• 1.5~2um laser/silicon mirrors

(concerns : ”soft” material and less-matured wavelength)

• Heavier sapphire feasible ?
• Frequency dependent squeezing achieved ?

(e.g. Eleonora Capocasa et al. PRD 93, 082004 (2016)

• High power laser (~500W input ?)
• Low round-trip-loss (< 10 ppm) ETM coating feasible ?
• Gravity Gradient Noise (GGN) canceling achieved ?

Just a few examples …

Plot by Michimura-san Heavy Sapphire Low freq. tuned Silicon 500W laser LVK

Well… then what should we do ?

Activate and keep the physics-driven discussions both inside and outside the collaboration

• List-up possible physics breakthroughs and target frequencies
• List-up current technical feasibilities and difficulties
• List-up advanced technical feasibilities and difficulties
• Listen to the voices from other GW projects and near-by communities

Conclusions

Broadband Narrowband Broadband

Win for the Brilliant physics !!