Pulsar Timing Time of arrival
Pulsar Timing
Time of arrival
Pulsar Timing
Model for expected arrival times incorporates:
spin-down, solar system orbits, pulsar velocity, pulsar orbits
Timing Residuals = Measured – Expected Pulse Arrival Times
Pulsar Timing
One year from today, the spin period will be
5.75745194393018(1) milliseconds
On our 50th wedding anniversary, it will be
5.75745201913820(6) milliseconds
Today at 7:45 pm, the spin period is 5.75745194212336(1) milliseconds
Pulsar Timing
Applications
What are gravitational waves?
1993 Nobel Prize
Existence of Gravitational Waves
Laser Interferometer Gravitational Wave Observatory (LIGO)
f ~ 1/ms (100 – 1000 Hz)
How can we detect them with pulsars?
f ~ 1/yrs (10-8 – 10-9 Hz)
Earth
Pulsar
Effect of a gravitational wave on pulsar residuals
For a 50 billion solar mass black hole binary at a distance of 200 million light years.
A Pulsar Timing Array
The Expected Correlation
The Expected Correlation
The Expected Correlation
The Expected Correlation
NANOGrav (North American Nanohertz Observatory for Gravitational Waves)
22 members from North America nanograv.org
Current Observations
< 100 ns RMS!
26 pulsars being timed with the Green Bank and Arecibo telescopes. Root-mean-square residuals from 100 ns to 1.5 μs.
How close are we?
The International Pulsar Timing Array (IPTA)
What will we see?
Detection of gravitational waves will be transformational!
We will no longer be limited to photons!
NOAO/AURA/NSF NOAO/AURA/NSF
Cambridge Cosmology Group