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.