Dennis Ugolini, Trinity University as long as the LIGO Science Collaboration SMU Phys

Dennis Ugolini, Trinity University as long as the LIGO Science Collaboration SMU Phys www.phwiki.com

Dennis Ugolini, Trinity University as long as the LIGO Science Collaboration SMU Phys

Becker, Brett, Field Editor has reference to this Academic Journal, PHwiki organized this Journal Dennis Ugolini, Trinity University as long as the LIGO Science Collaboration SMU Physics Seminar March 29, 2010 Document no. LIGO-G100214 News from the Laser Interferometer Gravitational-Wave Observatory (LIGO) Gravitational Waves Gravitational waves are transverse distortions of spacetime due to the motion of massive astronomical bodies. Expected sources: Inspiraling neutron stars/black holes (Asymmetric) supernovae Rotating pulsars Cosmic gravitational-wave background Expected properties: Quadrupole polarization Propagating at speed of light Strains of L/L = 10-21 or less SMU Physics Seminar, March 29, 2010 LIGO-G1000214 Hulse-Taylor Binary Pulsar LIGO-G1000214 SMU Physics Seminar, March 29, 2010 PSR 1913 + 16, measured in 1975 System should lose energy through gravitational radiation Stars get closer together Orbital period gets shorter

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Why Are We Looking “Chirp Signal” We can use weak-field gravitational waves to study strong-field general relativity. SMU Physics Seminar, March 29, 2010 LIGO-G1000214 The Fabry-Perot Michelson Interferometer SMU Physics Seminar, March 29, 2010 LIGO-G1000214 Uses light interference to measure path length difference between the two arms Each arm is a Fabry-Perot cavity, effectively increasing arm length Geometry ideally suited as long as quadrupole radiation The LIGO Project Max Planck Institute Andrews University Australian National Univ. Caltech Cardiff University Carleton College Charles Sturt Univ. Columbia University Embry-Riddle Aero. Univ. Etvs University Hobart & William Smith Institute of Applied Physics, Nizhny Novgorod Inter-University Centre as long as Astronomy in addition to Astrophysics, Pune Leibniz Universität Hannover LIGO Han as long as d Observatory LIGO Livingston Observatory Massachusetts Inst. of Technology Louisiana State Louisiana Tech McNeese State Univ. Montana State Univ. Moscow State Univ. NASA/Goddard Flight Ctr. Nat. Astronomical Observatory of Japan Northwestern University Rochester Inst. of Technology Ruther as long as d Appleton Lab. San Jose State Univ. Sonoma State Univ. Southeastern Louisiana Southeastern Univ. Southern University Stan as long as d University Syracuse University Penn State Univ. University of Melbourne Univ. of Mississippi Univ. of Sheffield Univ. of Texas at Austin Univ. of Texas at Brownsville Universitat de les Illes Balears Trinity University Univ. of Adelaide University of Birmingham Univ. of Florida Univ. of Glasgow University of Maryl in addition to Univ. of Mass. – Amherst University of New Hampshire Univ. of Michigan Univ. of Minnesota University of Oregon Univ. of Rochester Univ. of Salerno Univ. of Southhampton Univ. of Sannio at Benevento University of Strathclyde University of Western Australia University of Wisconsin-Milwaukee Washington State University SMU Physics Seminar, March 29, 2010 LIGO-G1000214 LIGO: Laser Interferometer Gravitational-Wave Observatory Detection, followed by astronomy LIGO Science Collaboration (LSC) includes many institutions Funded by US National Science Foundation

The LIGO Observatories LIGO Han as long as d Observatory (LHO) (4km in addition to 2km in same vacuum) LIGO Livingston Observatory (LLO) SMU Physics Seminar, March 29, 2010 LIGO-G1000214 LIGO Vacuum System SMU Physics Seminar, March 29, 2010 LIGO-G1000214 Vacuum at 10-9 torr to reduce light scattering in addition to momentum kicks to optics. One meter diameter arms, with chambers separated by 4’x4’ gate valves Serrated baffles included to disperse light scattered at optics Lengthy bake to remove adsorbed water vapor Seismic Isolation Passive (to reduce noise in sensitive freq. b in addition to ) Active (to improve lock acquisition/maintenance) SMU Physics Seminar, March 29, 2010 LIGO-G1000214

Suspended Test Masses SMU Physics Seminar, March 29, 2010 LIGO-G1000214 Optics are 25 cm diameter, 10 cm thick, 10.7 kg, of high purity fused silica. They must have <50 ppm scattering losses, <1 ppm absorption losses. The optics are suspended to attenuate seismic motion above the pendulum frequency. Science Run Timeline LIGO-G1000214 SMU Physics Seminar, March 29, 2010 SMU Physics Seminar, March 29, 2010 LIGO-G1000214 Seismic Internal thermal Shot noise in addition to pole frequency So Have We Detected Gravitational Waves Nope. SMU Physics Seminar, March 29, 2010 LIGO-G1000214 But the lack of detections puts interesting constraints on our universe: The properties of certain astronomical objects The populations of gravitational-wave sources The total energy density of gravitational waves Search Classifications LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Low Mass Binary Inspiral Search Results LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Covers first 18 months of S5 data – no detections as long as total mass < 35 M Limits assume NS = 1.35 solar masses, BH = 5.0 solar masses L10 = 1010 L (1 Milky Way = 1.7 L10) Kalogera et al., ApJ 601, L179 (2004) Kalogera et al., ApJ 614, L137 (2004) O’Shaughnessy et al., ApJ 633, 1076 (2005) O’Shaughnessy et al., ApJ 672, 479 (2008) B. Abbott et al., PRD 80, 047101 (2009) Bursts: GRB 070201 LIGO-G1000214 SMU Physics Seminar, March 29, 2010 GRB 070201 was short (0.15s), intense, in addition to from direction of M31 (770 kpc). Both Han as long as d detectors operating, exclude inspiral within 3.5 Mpc at 90% CL. Thus the gamma-ray burst was extremely unlikely to be an inspiral in M31. B. Abbott et al., ApJ 681, 1419 (2008) Other Burst Searches LIGO-G1000214 SMU Physics Seminar, March 29, 2010 B. Abbott et al., PRD 80, 102001 (2009) Other GRBs: One GRB every few days, 212 total during S5 All Sky Survey: Search as long as any signal between 64-2000 Hz in first year of S5 data. 90% CL rate limits shown at left. Also limits on strength: 10 kpc: < 1.9 × 10-8 M Virgo cluster (16 Mpc): < 0.05 M Crab Pulsar Search LIGO-G1000214 SMU Physics Seminar, March 29, 2010 The pulsar in the Crab has a rotational frequency of 29.78 Hz, in addition to is slowing: df/dt = -3.7 × 10-10 Hz s-1 dE/dt = -4.4 × 1031 W How much of this energy loss is due to gravitational wave radiation Apply matched filtering with templates at or near twice rotational frequency. Lack of detection implies: Less than 6% of energy loss due to gravitational waves Internal mag. field < 1016 G B. Abbott et al., ApJ Lett. 683, 45 (2008) Other Periodic Searches LIGO-G1000214 SMU Physics Seminar, March 29, 2010 All-sky survey search as long as periodic sources: First eight months of S5 fgw = 500-1100 Hz df/dt = -5 × 10-9 Hz s-1 to zero 95% CL strain limits shown at right (best in addition to worst spin orientations). Search is sensitive to neutron stars within 500 pc with eccentricity ~ 10-6. B. Abbott et al., PRL 102, 111102 (2009) Stochastic GW Background LIGO-G1000214 SMU Physics Seminar, March 29, 2010 95% CL on gravitational-wave energy density from S5 data: B. Abbott et al., Nature 460, 990 (2009) Limit supercedes Big Bang Nucleosynthesis bound, constrains certain cosmic string in addition to pre-Big Bang models. Developments Since S5 LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Data sharing agreement with VIRGO collaboration beginning in 2007 “Trigger passing” – real-time alerts to: Swift satellite (X-ray) TAROT, QUEST wide-field telescopes (optical) Program began in December 2009 Enhanced LIGO – improved sensitivity x4 increase in laser power DC demodulation Thermal lensing compensation RF Heterodyne Demodulation LIGO-G1000214 SMU Physics Seminar, March 29, 2010 From S. Hild et al., Class. Quantum Grav. 26, 055012 (2009). In Initial LIGO, an electro-optic modulator applied radio-frequency sideb in addition to s to the carrier light. The interferometer is operated at the dark fringe to minimize shot noise. The carrier light is resonant in the arms, while the sideb in addition to s are not. The output is electronically mixed with the applied RF frequency, giving a linear correction signal. DC Homodyne Demodulation LIGO-G1000214 SMU Physics Seminar, March 29, 2010 In DC demodulation, the interferometer is operated slightly off the dark fringe, in addition to this light mixes optically with the sideb in addition to s. Advantages: Simplified electronics Reduced phase noise Larger non-RF photodiodes Requires good laser intensity stabilization & output mode cleaner (OMC). The OMC in turn requires better seismic isolation. From S. Hild et al., Class. Quantum Grav. 26, 055012 (2009). Active Seismic Isolation LIGO-G1000214 SMU Physics Seminar, March 29, 2010 New seismic isolation stacks installed in output mode cleaner chamber at each site. Six sets of position in addition to velocity sensors (GS-13 seismometers) feed back to coil actuators. Order of magnitude improvement over wide frequency range. Becker, Brett Powerboat Magazine Field Editor www.phwiki.com

Isolation Stack Installed LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Thermal Compensation System LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Fused silica is a poor conductor of heat, in addition to the higher power laser delivers a lot of heat! Uneven heating causes reflective properties to become a function of position; a translation of the beam creates a phase shift that mimics a signal. In Enhanced LIGO, 25W carbon dioxide lasers scan the optical surface in an annulus pattern, flattening the surface temperature profile. Sensitivity Improvement LIGO-G1000214 SMU Physics Seminar, March 29, 2010 S6 began on July 7, 2009, coincident with VIRGO’s second science run. S6 will continue through Oct. 2010. PRELIMINARY

The Need as long as Advanced LIGO Goal: factor of ten improvement in sensitivity at all frequencies x10 increase in sensitivity = x1000 volume of sky searched Inspiral event rate from one every few years to one every few days! Resolution improved as long as astronomy Assembly underway, transition begins this fall SMU Physics Seminar, March 29, 2010 LIGO-G1000214 Initial LIGO Projected Sensitivity LIGO-G1000214 SMU Physics Seminar, March 29, 2010 180 Watt Laser LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Laser Zentrum Hannover e.V.

My Contribution: Charging LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Charge buildup on optic surfaces Mechanical contact with other materials Friction with dust during pumpdown Exposure to electrostatic drive Particle showers from cosmic rays Potential concerns Electric fields interfere with positioning control Dust held to surface, increasing absorption Motion generates low-frequency suspension noise The goal is to measure the charging magnitude, relaxation time constant, in addition to spatial variation, in addition to find a noncontact discharging method. Kelvin Probe Measurements LIGO-G1000214 SMU Physics Seminar, March 29, 2010 Summary No detections yet, but results of S5 science run have put interesting constraints on our nearest neighbors Enhanced LIGO science run ongoing Advanced LIGO construction already underway, aiming as long as sensitivity to detect GW sources with regularity by 2014-5 SMU Physics Seminar, March 29, 2010 LIGO-G1000214

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