1. Gravitational Wave Astronomy with a Radio Telescope
Fredrick A. Jenet
Professor of Physics and Astronomy/Director of External Affairs
Center for Gravitational Wave Astronomy
University of Texas at Brownsville

2. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Collaborators
George Hobbs
ATNF/CSIRO
Australia
Dick Manchester
ATNF/CSIRO
Australia
李柯伽
KJ Lee
CGWA/UTB
Willem Van Straten
Swineburne
Australia
Joris Verbiest
Swinburne
Australia
Andrea Lommen
(Franklin & Marshall)
Shane L. Larson
Weber State
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

3. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Key Points
We are building a Galactic Scale Gravitational Wave Observatory using Radio Pulsars.
This “Observatory” will test both physical and astrophysical theories.
Pulsars can also be sources of GWs.
Arecibo is playing an important role the GW effort: Pulsar searching and long term pulsar timing.
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

4. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Gravitational Waves
“Ripples in the fabric of space-time itself”
gmn = hmn + hmn
Gm n (g) = 8 p Tm n
- ¶2 hmn /¶2 t + 2 hmn = 4p Tmn
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

5. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Radio Pulsars
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

6. The Big Picture of G-wave Detection
VLF LF HF
10-5
10-10
ELF
10-15
10-20
10-25
10-4
102
10-8
10-16
9/17/2018
Frequency, Hz

7. Science in the Nano-Hz Gravitational Wave Band
Binary Supermassive Black Hole formation and Evolution
Galactic Dynamics
Equation of State of the Early Universe (Quintessence)
Study of Cosmic Strings
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

8. Other science with GWs and pulsars
Using pulsars as a source of GWs
Probe NS structure
Need long term timing in E&M to search for emitted GWs using LIGO.
Need to find many young, nearby, high period derivative pulsars.
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

9. How do we detect/limit GW using radio pulsars?
Consider small perturbations from a flat space-time:
The slight change in the rate at which pulsar pulses arrive at Earth is given by:
Pulsar timing observations measure the timing residuals:
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

10. Sensitivity of pulsar timing to GWs
Cosmic Strings
1010 Msun BBH
@ a distance of 20 Mpc *
3C 66B
10-12
Relic G-waves
109 Msun BBH
@ a distance of 20 Mpc
10-13
SMBH Background h
10-14
10-15 *
OJ287
10-16
10-17
3  10-11
3  10-10
3  10-9
3  10-8
3  10-7
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Frequency, Hz

11. Detecting a Stochastic Background of GWs
Pulse arrival time fluctuations from different pulsars will be correlated:
C(ij) = <RI Rj>
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

12. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
(Plot by
KJ Lee)
The exact form of the correlation curves depends on the
polarization properties of the GWs.
Our ability to detect and characterize these correlation curves is
directly proportional to the number of pulsars.
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

13. What are the odds of detecting the stochastic background?
For 20 pulsars, with 100 nano-second RMS timing residuals, 10 years of timing observations: ~50%
Up the number of pulsars to 40 and we have >95%.
Big Ifs: The majority of SMBHs form by galaxy merger and dynamical friction allows the two holes to get close together.
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

14. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
3C 66B:A Case Study
Orbital Motion in the Radio Galaxy 3C 66B: Evidence for a Supermassive Black Hole Binary
Hiroshi Sudou,1* Satoru Iguchi,2 Yasuhiro Murata,3 Yoshiaki Taniguchi1
Supermassive black hole binaries may exist in the centers of active galactic nuclei such as quasars and radio galaxies, and mergers between galaxies may result in the formation of supermassive binaries during the course of galactic evolution. Using the very-long-baseline interferometer, we imaged the radio galaxy 3C 66B at radio frequencies and found that the unresolved radio core of 3C 66B shows well-defined elliptical motions with a period of 1.05 ± 0.03 years, which provides a direct detection of a supermassive black hole binary.
Volume 300, Number 5623, Issue of 23 May 2003, pp
Copyright © 2003 by The American Association for the Advancement of Science. All rights reserved.
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

15. Sudou et al.’s adopted parameters for 3C 66B
Mt = 5.4  1010 Msolar
Mass ratio = .1
Mchirp = Msolar
Orbital period = 1.05  .03 yrs
Distance = 85 Mpc (H=75 km/s/Mpc)
h  Mchirp5/3 W2/3 / D  10-12
R = h/W = 2 m s
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

16. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
The expected signature of GWs from 3C66B on PSRB
From Jenet, Lommen, Larson, & Wen, ApJ May 10th 2004
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

17. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Here and Now
There and Then
The observed residuals contain a component that depends on what the binary system was doing 3000 years ago!
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

18. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

19. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Constraints on 3C66B
The parameters adopted by Sudou et al. can be ruled out with 98% confidence.
Mchirp < 0.7 x 1010 Msolar assuming e < 0.01.
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB

20. Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB
Summary
We are building a Galactic Scale Gravitational Wave Observatory using Radio Pulsars.
Probe the SMBH binary population
Limit Cosmic String theories
Limit GW from the early universe
This “Observatory” will test both physical and astrophysical theories.
Measuring the polarization properties of GWs
Pulsars can also be sources of GWs.
Non-spherical mass distributions of pulsars.
GWs will be detectable in the LIGO band ( Hz)
Arecibo is playing an important role the GW effort
Pulsar searching
Long term pulsar timing.
9/17/2018
Fredrick Jenet, Center for Gravitational Wave Astronomy, UTB