A proposal for additional Low Frequency

Gravitational WaveInterferometric Detectors

at LIGO

Riccardo DeSalvo

California Institute of TechnologyGlobular Cluster 17th October 2003

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Globular Cluster MeetingState College, 17-21 October 2003

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Status of observationsnow and here!!

• TAMA has been running for >3 years– Steadily improving sensitivity >100 Hz– < factor of 10 from nominal sensitivity

• LIGO has been acquiring data for > 1 year (with GEO)– Steadily improving sensitivity ~100 Hz– < factor of 10 from nominal sensitivity

• Virgo commissioning– Taking data in ~< 1 year– > 20 Hz

• AdLIGO starting up– Foreseen for > 2007– > 40 HzLow Frequency Threshold defined as mirror thermal noise corner!

Globular Cluster MeetingState College, 17-21 October 2003

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Why LF-GWIDs?• Adv-LIGO will cover the detection of pulsars, NS-

NS and low-mass BH inspirals, the coalescence phase, and other GW physics with its best sensitivity around100 Hz

• Can ground based GWIDs monitor even lower frequencies

• Is this useful to study globular clusters?

Globular Cluster MeetingState College, 17-21 October 2003

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What is necessary for a LF-GWID?

• GW Interferometers can be optimized for LF with the following changes

– Reduce beam power and different finesse (rad. Pressure)

– Use longer suspensions (susp. TN)

– Use Supersized, double weight, mirrors (coating TN, rad. Pr)

– Use Fused Silica (instead of Sapphire) mirrors (bulk TN)–

• LF-tuning would divert AdLIGO from its original mission!

• Need operation of separate Low and High Frequency complementary interferometers

Globular Cluster MeetingState College, 17-21 October 2003

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AdL LF-GWID complementarity

NewtonianNoise limit

Globular Cluster MeetingState College, 17-21 October 2003

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AdL LF-GWID complementarity

End inspiral frequencyFirst BH Kerr resonance

Merger phase follow-up in the frequency mass area above the yellow line

BH ring down in the frequency mass area above the purple line

Triggered searchesLF triggerHF strongly relativisticsignal study

Template Signal integration

Globular Cluster MeetingState College, 17-21 October 2003

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AdL and LF-GWID

Blue:Low seismicDay

Purple:High seismicDay

Green:Ad-LIGO

3.6 Gpc@37+37sm

Seismic variability

1.15 Gpc@16+16 sm

Globular Cluster MeetingState College, 17-21 October 2003

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Can we accommodate a LF interferometer next to Adv-LIGO?

• There seems to be space in the LIGO beam pipe just above and forwards of the Adv-LIGO mirrors

• Advanced LIGO nominal beam positions

adv.-LIGO 340 mm diameter

adv-LIGO 340 mm diameter

proposed 430 mm diameter mirror

Globular Cluster MeetingState College, 17-21 October 2003

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And there appears to be space in the halls

Virgo-like towersTAMA-like towers

Globular Cluster MeetingState College, 17-21 October 2003

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Conclusions

• IMBH are important and compelling potential GW sources for a LF interferometer

• Optimized LF sensitivity would allow: – Increase quite significantly the explored volume in

the Universe for heavier mass objects(3.6 Gpc, real cosmology reach).

– Study of the genesis of the large galactic BH (believed to be central to the dynamics of galaxies)

– Mapping the globular clusters in our neighborhood – Enhancement of the performance of both Virgo and LIGO

• They would be “triggered” by the LF detection and follow up studying final inspiral and merge signals

• Advanced LIGOs are freer to be narrow banded• Splitting up the frequency range between two different interferometers

eases lots of design constraints and allows better performance from both

Globular Cluster MeetingState College, 17-21 October 2003

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LF-GWID proposal pointers

Should all be in LIGO DCC, if not availableLF-GWID Amaldi proceedings (LIGO- P030047-00-D): www.ligo.caltech.edu/~desalvo/manuscript-Amaldi2003.docLF-GWID Elba proceedings (LIGO-P030040-00-D):www.ligo.caltech.edu/~desalvo/DESALVO_ELBA_manuscript.doc

LF-GWID Amaldi power point presentation (LIGO-G030332-00-R ):www.ligo.caltech.edu/~desalvo/desalvo_amaldi.pptLF-GWID Elba power point presentation (LIGO-G030292-00-R):www.ligo.caltech.edu/~desalvo/desalvo-elba.ppt

Globular Cluster MeetingState College, 17-21 October 2003

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Aspen GWDAW workshop winter 2004

• The LIGO S. C. equivalent of this informal meeting is the Aspen meeting.

• February 15 to 21st 2004• Please consider participating. • Input on what is relevant and important to

make good astronomy is very important.• You can help !!