CENTRA report

1
Gravitational wavesastronomy for the new
millennium
Vitor Cardoso (CENTRA/IST U. Mississippi)?
Collaborators Berti, Bruegmann, Gonzalez, Pani,
Pretorius, Sperhake, Will, Witek, etc
IBERICOS 2009, Madrid, 16 April
(Image MPI for Gravitational Physics/W.Benger-Z)
2
Plan
GWs in GR Coalescence of black hole
binaries in GR Other theories

3
What are GWs?

polarization
x polarization
Wave equation c!
Observable
Gws are tidal forces!
4
Do they exist?
slow down of a binary pulsar
5
Do they exist?
slow down of a black hole in quasar OJ 287
strong-field tests
Valtonen et al, Nature452, 851-853 (17 April
2008)
6
Detection
7
Typical signal for coalescing binaries
8
Typical stretch of data
9
Typical needle in a haystack problem
(but with a smaller needle)
10
Typical needle in a haystack problem
11
Matched filtering
12
Matched filtering
13
Matched filtering
14
Matched filtering
15
Matched filtering
16
Matched filtering
17
The merger problem we need NR
Lack of knowledge
Wrong filter
Mismatch
Decreased SNR
3 Mismatch 10 lost events!
18
BH Binary Coalescence
Rates for LISA (similar variations for LIGO)
19
BH coalescence
Courtesy Marcus Thierfelder and Bernd Bruegmann
20
Typical signal for BH binaries
Inspiral Merger Ringdown
(Berti, VC, Sperhake, Gonzalez, Brugmann, Hannam
Husa,PRD76064034,2007)?
21
Inspiral
Luminosity distance
Angular resolution (sterad)?
reduced mass
Chirp mass
(Faye et al 06, Kidder 08)
22
Inspiral

• Inspiral PN waveforms High-precision tests of
  GR
• Mass, distance, angular location to fractions of
  a percent

Luminosity distance
Luminosity distance
Angular resolution (sterad)?
Angular resolution (sterad)?
reduced mass
reduced mass
Chirp mass
2x106M (solid) and 2x107M (dashed)?(Berti,
Buonanno Will, PRD71084025,2005)?
23
Inspiral

• Inspiral PN waveforms High-precision tests of
  GR
• Mass, distance, angular location to fractions of
  a percent
• Propagation speed, Polarization states
• Masslessness of graviton speed depends on
  wavelength, therefore phasing changes during
  inspiral (Arun and Will, 09)
• EOS for dark energy identify host galaxy and
  measure redshift from EM. Distance and redshift
  gives EOS (Arun et al, 08)

Luminosity distance
Angular resolution (sterad)?
reduced mass
24
BH ringdown characteristic modes

(Leaver 85 Berti, VC Starinets, 09)
f 12 Msun/M kHz 0.012 (106Msun)/M Hz t
55x10-6M/Msun s 55 M/(106Msun) s
25
No-hair tests

• One mode detection
• Suppose we know which mode we are detecting
  (eg. lm2) then
• Measure of black holes mass and angular
  momentum
• (Echeverria 89, Finn 92)

f(M,j), t(M,j) M(f,t), j(f,t)

• Multi-mode detection
• First mode yields (M,j)
• In GR, Kerr modes depend only on M and j
• second mode yields test that we are observing
  a Kerr black hole, if we can resolve the modes

(Dreyer et al. 05 Berti, VC Will 06)
26
Ringdown LISA
j0,0.8,0.98
Berti, VC Will, PRD71084025,2005)?
27
On-going

• Credible consistent theories of gravity
• Chern-Simons (Sopuerta Yunes 09, Alexander
  Yunes 08), Dilaton-Gauss-Bonnet (VC Pani,
  09), etc.
• Maybe a general framework? (Pretorius
  Yunes, 09)
• Numerical Relativity in different theories (see
  Helvis talk)

• Work in progress
• Good news for gravitational-wave detection
• Bad news for quest for corrected theory of
  gravity

28
Conclusions

• Exciting times for gravitational wave astronomy
• Advances in theory and numerical relativity
• Earth-based detectors have reached design
  sensitivity
• Probe central engine for GRBs
• Demographics of very compact objects (mass
  spin to better than 1!)?
• Does GR describe strong field regime?
• ?

29
Thank you
30
Typical BH binary
31
Order of magnitude estimate
For a coalescing compact object into a black hole
Distance Earth-Sun (1.5 x 107 km). stretch
es by a fraction of an atom!
32
BH coalescence
33
The merger problem
34
Interferometry
Hanford, WA
Livingston, LA
35
BH ringdown combing 3 hairs