Requirements for a 3G GW observatory

Transcription

1 Requirements for a 3G GW observatory SOME THOUGHTS FOR DISCUSSION HARALD LÜCK

2 3G Observatory & 3G Network Requirements = f(science, funding, politics, ) requirements for an individual observatory and the requirements for the network of observatories are closely coupled ET, Europe LIGO Voyager Hanford CE, US Advanced Virgo, Cascina KAGRA LIGO Voyager Livingston LIGO INDIA KAGRA 3km

3 Basic assumptions for the 3G era Several advanced detectors (frequently running) have reached ca. 5x today s sensitivity We have exploited the capacity of the 1&2 G infrastructure No further improvements possible / reasonable We can afford at most two 3G observatories of ET/CE class 40 km size is almost impossible in Europe underground infrastructure in Europe, size limited by tunnelling costs

4 Future GW Network > 2025 ET, Europe LIGO Voyager Hanford CE, US LIGO Voyager Livingston Advanced Virgo, Cascina LIGO INDIA KAGRA KAGRA 3km

5 Future GW Network > 2025 Until when? ET, Europe LIGO Voyager Hanford CE, US LIGO Voyager Livingston Advanced Virgo, Cascina LIGO INDIA KAGRA KAGRA 3km

6 Lifetime of Infrastructures We are aiming for a 3G infrastructure lifetime of ca. 50 start of 3G era ( >2025) LIGO&Virgo infrastructures will be 30 years old What is their life expectancy? Say 1 more decade 2035 (KAGRA longer) And then? only 3G + KAGRA We need new infrastructures capable of hosting a 3G network

7 Science driven requirements Stellar Evolution at High Red-Shift: Black Holes from the first stars At least moderate luminosity distance needed Cross-checking Cosmology and the Dark Energy EOS Needs precision luminosity distance and localization for EM follow-ups (for redshift) Checking GR in extreme regime High SNR needed luminosity distance and localization not essential Content: LIGO-G , D. Sigg, S. Balmer

8 Needed for Science Luminosity distance (i.e. strain amplitude) For 2 L (non-co-located) or one Δ : amplitude strongly correlated with position Thus: science that needs either luminosity distance or localization accurately, requires at least two observatories with at least three interferometers Content: LIGO-G , D. Sigg, S. Balmer

9 Remarks Triangulation for localization? Depends on timing resolution worse for heavy chirp masses. Doesn t work at detector null The full polarization tensor also gives localization. Three non-co-aligned detectors needed to resolve the polarization tensor Content: LIGO-G , D. Sigg, S. Balmer

10 Timing resolution for SNR=10 LIGO-P Content: LIGO-G , D. Sigg, S. Balmer

11 What can we do with 2 sites? Two co-located L vs Δ: almost identical Either two Δ OR Δ plus L (at least 3 IFO): Roughly quarter-planet (pi/2) away for pol. P discusses two Δ. Conclusion: Two observatories (with full pol) can localize fairly well Although still a few times worse than 3 observatories. LIGO-G , D. Sigg, S. Balmer

12 Position resolution w/o & with timing LIGO-P LIGO-G , D. Sigg, S. Balmer SNR 100 / BW 50Hz

13 Using the legacy? What about using 1 ET-class detector together with (upgraded) 2 nd gen network? Any high-z / cosmological work difficult Only use case: precision measurement of really high SNR observations e.g Constrain GR Measure spin effects etc. LIGO-G , D. Sigg, S. Balmer

14 Requirements For a single observatory Sensitivity (>= 10x advanced, initially) Polarisation resolving (2L vs ), benefits of co-location? Longevity (life time ca. 50 yrs) Low environmental noise & low additional facility noise (go to a quiet location and keep it quiet) Capacity to host different detector topologies In the limits of an L or shaped overall geometry Versatility of infrastructure for implementation of future detectors (do not severely limit upgrading options by infrastructure design) What are the benefits of a null stream? (L or )? ( Stefan Hild)

15 Requirement: Wideband sensitivity Sensitive to a wide frequency range Low frequencies: maximise detection efficiency cosmological population estimate Mid - high frequencies: merging/ringdown phase of CBCs / Supernovae NS EOS BHs through Cosmic hist. Explosive Phenomena Extreme Physics Single interferometer / Xylophone?

16 Requirements for the 3G network As good pointing resolution as possible (source identification for Multimessenger Astronomy) Important in which frequency range? How much can A++ detectors do? (in their lifetime) Lifetime of A++-facilities? Overlap with 3G? ET, Europe LIGO Voyager Hanford CE, US Advanced Virgo, Cascina LIGO Voyager Livingston LIGO INDIA KAGRA KAGRA 3km

17 Non-Science Requirements Which long term duty factor to aim for? May be a drawback if multiple detectors are in one place as work in one place can disturb other detectors. Is it sufficient to have satellite caverns e.g. 300m away? Mind: an underground observatory may only be ca. 200m below ground anyway. Avoid funding peaking: Start with single 3G observatory + A++ detectors (for pointing) add 2 nd 3G observatory 5-7 years later Depends on political / funding boundaries On the European side funding must come mainly from national funding agencies (EU budget insufficient) Pan-European participation

18 Next steps??? Strengthen world-wide coordination for planning a 3G Network; This meeting is a very positive first step Define upgrading steps to Ultimate Advanced Detectors Estimate lifetime of 2G infrastructures + costs of operation/upgrades/maintenance This defines the timescale and needs for the first stage of a 3G Network We need an organisational structure to move on in a coordinated way

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20 Timing resolution for SNR=10 LIGO-P