Gravitational Waves and the ARCC@UWM research programXavier SiemensSummary• Why look for gravitational waves?• Detecting them with pulsars• Our activitiesWhat are Gravitational Waves?• Predicted by Einstein in 1918, gravitational waves are ripples in space and time analogous to electromagnetic wavesElectromagnetic waves: light, microwaves, radio, TV signalsmoving chargeGravitational wavesmovingmass...mass is the “charge” of gravity...• Need a lot of mass moving very fast to generate measurable gravitational wavesGravity is weak. Ratio of electric repulsion to gravitational attraction for protons:FEMFG= 1036What are Gravitational Waves?• Predicted by Einstein in 1918, gravitational waves are ripples in space and time analogous to electromagnetic wavesElectromagnetic waves: light, microwaves, radio, TV signalsmoving chargeGravitational wavesmovingmass...mass is the “charge” of gravity...• Need a lot of mass moving very fast to generate measurable gravitational wavesGravity is weak. Ratio of electric repulsion to gravitational attraction for protons:FEMFG= 1036What are Gravitational Waves?• Predicted by Einstein in 1918, gravitational waves are ripples in space and time analogous to electromagnetic wavesElectromagnetic waves: light, microwaves, radio, TV signalsmoving chargeGravitational wavesmovingmass...mass is the “charge” of gravity...• Need a lot of mass moving very fast to generate measurable gravitational wavesGravity is weak. Ratio of electric repulsion to gravitational attraction for protons:FEMFG= 1036Why look for them?• We only see a tiny fraction of electromagnetic wavesWhy look for them?Gravitational wave sky?Visible light X-RaysAnother example: Crab nebulaStellar EvolutionWhat are pulsars?• Pulsars emit regular short bursts of radio (electromagnetic) wavesbeam of radio wavesmagnetic fieldrotation axisDetecting gravitational waves with pulsars• Neutron stars (pulsars) are extremely dense and rotate VERY stably. So the pulses we see arrive at very steady rates.• Gravitational waves are ripples in spacetime that change the arrival times of the steady train of radio pulses emitted by the pulsar gravitational wavesIn Reality...Even without gravitational waves pulses don’t arrive so steadily:• Most pulsars are in binary systems• The Earth moves (daily and yearly)• The pulsar may have motion of its own• BUT: We measure and subtract out all these effectsgravitational wavesAfteraccountingforalleffectsthispictureisOKThe Pulsar Timing ArrayThere are about 2000 known pulsars in our galaxy. Only 20 of them are suitable for gravitational wave detectionyou are hereOur main task is to find more!Searching for new pulsars at Arecibo, PRActivities• Observing: 4 sessions. Late afternoon of October 11, 15, 20, 21. • Have ability to control Arecibo remotely from UWM• We’ll circulate an e-mail. Sign up!ARCC = Arecibo Remote Command Center• Finding pulsars• Candidate viewing:‣Candidate viewing training sessions this week in Physics 148• Last step of blind search for new pulsars• Would like participants (you) to look through > 100 candidates/week.ActivitiesRegister at: http://arcc.phys.utb.edu/viewer/index.php• Astronomy Club Mondays at 7pm.- Relatively informal meeting - We will hear 20 minute talks about topics of astronomy, physics, and mathematics related to the research.- Question answer session about topic being discussed, other topics, and interesting candidates (save these while you look through them during the week)ActivitiesFuture Research Activities• Developing and implementing techniques for gravitational wave searches in pulsar timing data (see e.g. http://arxiv.org/abs/0809.0701)• Machine-learning based candidate viewing (teach a neural network to do your job--suggested by some of you in interview)• LASER Interferometer Gravitational-wave Observatory (LIGO) observing (traveling to the sites)• LIGO data analysisSensitivitytoGWsfromdifferentskylocationsfor20knownsuitablepulsarsPeople involvedLarry PriceUWM postdocMelissa AnholmUWM Graduate StudentJean CreightonPlanetarium DirectorJessica ClaytonUWM postdocRick JenetUTB facultyCame up with ARCC program Jeff AndersonCity-wide Mentor Teacher MPSKathy GustavsonNicolet High