Current Results and Future Capabilities of Pulsar Timing
Andrea N. LommenInternational Liaison for NANOGrav
Associate Professor of Physics and Astronomy
Head of Astronomy Program
Director of Grundy Observatory
Franklin and Marshall College
Lancaster, PA
“Pulsar Timing: No longer a blunt instrument for gravitationalWave detection” Lommen, Journal of Physics, 2012
IPTA = NANOGrav + EPTA + PPTA• NANOGrav = North American
Nanohertz Observatory of Gravitational Waves
• EPTA = European Pulsar Timing Array• PPTA = Parkes Pulsar Timing Array
(Australia)
The International Pulsar Timing Array
www.ipta4gw.org
Pulsar2Pulsar1
Earth
Photo Courtesy of Virgo
Adapted from NASA figure
Detectability of a Waveform
€
gμυ = ημυ + hμυ
dt
dλ
⎛
⎝ ⎜
⎞
⎠ ⎟2
= δ jk
dx j
dλ
dx k
dλ+
dx j
dλ
dx k
dλh jk t,
r x ( )
dt =∫ dλ −1− kmnm
1+ kmnm∫ dλn j∫ n kh jk t λ( ),r x λ( )( )
Residual = e jknjn k h0
21− kmnm( ) f t0( ) − f t0 − L 1+ kmnm
( )( )[ ]
where h jk t,r x ( ) = h0 ′ f t − ˆ k ⋅
r x ( )e and L is the distance to the pulsar.
A sense of what’s detectable
€
h =M
53
P2
3dτ = hP
τ =M
53P
13
d
τ = 50ns
M
2 ×109 MΘ
⎛
⎝ ⎜
⎞
⎠ ⎟
53 P
1year
⎛
⎝ ⎜
⎞
⎠ ⎟
13
d
100Mpc
⎛
⎝ ⎜
⎞
⎠ ⎟
NANOGrav Residuals
Adapted from Demorest et al (2013) by David Nice
NANOGrav 5-year timing results summary
Demorest et al (2013)
Constraining the Properties of Supermassive Black Hole Systems Using Pulsar Timing: Application to 3C 66b, Jenet, Lommen, Larson and Wen (2004) ApJ 606:799-803. (NANOGrav)
Data from Kaspi, Taylor, Ryba 1994
10
Orbital Motion in the Radio Galaxy 3C 66B: Evidence for a Supermassive Black Hole Binary Sudou, Iguchi, Murata, Taniguchi (2003) Science 300: 1263-1265.
Re
sid
ual
(ms)
-10
10
0
Re
sid
ual
(ms)
-10
10
0
Simulated residuals due to 3c66b
Hellings and Downs Curve (Overlap Reduction Function)
Courtesy of Rick Jenet (NANOGrav) and George Hobbs (PPTA). Original figure from Hellings and Downs (1983).
Yardley et al 2011 (PPTA)
• Measure the polarisation properties of gravitational wave
• Test theories of gravity…! (NANOGrav -> EPTA)
Lee et al. (2008)
Sydney Chamberlin (UW Milwaukee, NANOGrav) Non-Einsteinian
gravitational waves using PTAs
Chamberlin et al, PhRvD (2012)
Yardley et al 2011 (PPTA)
Van Haasteren et al 2011 (EPTA)
Figure by Paul Demorest, NANOGrav (see arXiv:0902.2968 and arXiv:1201.6641)
MBH-M
BH (indiv)
Gal NS/BH
BH-BH (indiv)
PSRs
Sesana, Vecchio and Volunteri 2009 (NANOGrav,
EPTA)
Method used from: Ellis, Siemens, and Creighton ApJ 2012. Plot courtesy of Xavi Siemens.
(NANOGrav) Similar to work of Yardley et al (2011, PPTA) but about a factor of 7 more sensitive
Ability to constrain position is
function of h
Kejia Lee (EPTA) et al,2011, MNRAS
From Sesana & Vecchio (2010), EPTA
100 pulsars, SNR=10
Sky position
frequency
Inclination angle
Source amp
phase
Polarization angle
A 5 x 109 solar-mass black hole binary coalescing 100 Mpc away. 30 IPTA pulsars, improved by 10, sampled once a day.
Thank you to Manuela Campanelli, Carlos O. Lousto, Hiroyuki Nakano, and Yosef Zlochowerfor waveforms. Phys.Rev.D79:084010 (2009). http://ccrg.rit.edu/downloads/waveforms
From Finn & Lommen 2010 (NANOGrav)
Kejia Lee et al (2010), EPTA
Measuring the graviton mass
Cosmic String Tension Upper Limits
• Sotirios Sanidas, Richard Battye, and Ben Stappers (U of Manchester and Jodrell Bank Center for Astrophysics, EPTA) 2011
Measuring spin-orbit precession of
BHBs using pulsar timing by Mingarelli et al, PhRvL (2012)
Trevor Sidery, Kat Grover, Rory Smith, Chiara Mingarelli.
• Deng & Finn (NANOGrav, 2011) curvature of the waveform
• Pitkin & Woan (2012) a clever use of the “pulsar term” to increase the possibility of detecting a burst signal. (LIGO!)
The GW sky is not isotropic in the PTA band!(Joe Simon, Franklin and Marshall College,
NANOGrav, in prep)
• Should we expect nHz gravitational-wave hotspots?
New Telescopes
A Large European Array for Pulsars = LEAP!
Coherently add pulsar observations from 5 of the largest telescopes in Europe (and the world!) to obtain most precise TOA’s for GW detection.
Combine telescopes to form a phased array, a telescopewith equivalent size of a 200 m dish - ~5% SKA!
A LEAP in collecting area.
Funded by European Research CouncilAdvanced Grant (PI Kramer).
3030
Unique Karst depression as the siteActive main reflectorCable - parallel robot feed support100 米
300 米500 米
Five-hundred-meter Aperture Spherical radio Telescope (FAST)
GW-sensitivity
IPTAIPTA+ FAST
We need & want people to join us
• Lots of data, low on people-power• $6.5M grant from NSF -> NANOGrav to
foster international collaboration.• Student and faculty exchanges.
The Pulsar Data Challenge
• Opened a week ago (March 23)• Will close in Sept• Go to www.ipta4gw.org
Summary
• Pulsars make a galactic scale gravitational wave observatory which is poised to detect gravitational waves in 5-10 years.
• Stochastic, single sources, alternate polarizations, waveform and location recovery, mass of the graviton, spin-orbit coupling, cosmic strings…
• Coopetition works even though it’s not a real word• Please get involved, through data challenges is one
way, student and faculty exchanges another
• We expect to be surprised.
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