20160503_JVvanHeijningen_GWaperture

J.V. van Heijningen (jvnheijn@nikhef.nl)
Aperture, Maastricht| May 3rd , 2016

2|45 J.V. van Heijningen (jvnheijn@nikhef.nl)
Nikhef - Amsterdam
•  NaHonal InsHtute for Subatomic Physics
•  UniversiHes: UvA, VU, UU, RUG, RUN
•  ~250 employees
•  Excellent infrastructure, Tier-1 grid

•  ScienHﬁc program:
•  LHC @ Cern
•  Atlas, Alice and LHCb
•  AstroparHcle physics
•  Virgo, Auger, Antares/KM3Net, Xenon

•  Partners
•  SARA, AMSIX, KVI, MESA+, Lofar,
•  KNMI, TNO, ESA
•  Highly specialized workshop

Before we start…

The history of gravity
•  Newton (1687): gravity is an instantaneous force that one
mass exerts on another mass
•  Einstein (1915): gravity is a curvature of space<me because
of the mass
8G Tαβ αβπ=

New York Times, November 10th , 1919
Does light really bend?

Friedwardt Winterberg (1955): use of atomic
clocks to test General RelaHvity
GPS (Global Posi<oning System)
Sputnik (1957): Doppler effect provides
locaHon (20 en 40 MHz radiosignals)
GPS (1973 1st idea, 1978 1st satellite,
1993 operaHonal)
Clocks run faster because of weaker gravity,
off by 11 km per day when GR not used
All tests done with GR comprise of tests in
weak, sta<c fields

What about the dynamics?

Two big masses, spiralling towards each other
AcceleraHng masses (with big quadrupole moment) put a strain h on
spaceHme @ distance d

Recipe for a strong one: binary system of NSNS NSBH or BHBH

ddt
Qd
c
G
h
12
2
2
4
≈ h =
2ΔL
L

Expected astrophysical sources
•  Compact binary coalescence
•  Spinning non-spherical neutron stars
•  Supernovas
•  StochasHc background

Russell A. Hulse
Joseph H. Taylor, Jr.
In 1974, the ﬁrst binary system
with a pulsar was discoverd

Period ~ 8h, GW emission
shortens the period

Indirect detecHon of GWs
Nobelprize 1993
Gravita<onal waves are real: PSR B1913+16
ΔtP [s] Periastron advance
oﬀ by <0.2%

50 years ago, measurements started..
Einstein thought we would never directly measure gravitaHonal waves
2G
c4
=10−44
s2
kg−1
m−1
ddt
Qd
c
G
h
12
2
2
4
≈ , but

…and 30 years ago: huge interferometers
Eﬀect of a gravitaHonal wave on a
ring of test masses
Interferometer:

The ﬁrst detec<on! GW150914

The paper!
get your copy at papers.ligo.org

The Advanced LIGO detectors
LIGO Virgo collaboraHon
had 2 detectors operaHonal
last year September

Virgo will join later this year

Journey of a Gravita<onal Wave

The signal was loud!
•  Found in both unmodeled and modeled searches (analysis pipelines)
•  ‘Modeled pipeline’ has analyzed 16 days of LIGO data:
•  False alarm rate <1 in 203.000 year
•  Signiﬁcance > 5.1 σ

The two black holes
Parameters are determined
by comparing millions of ‘trial
waveforms’ in a 15-dimensional
parameter-space with the
measured signal

Tes<ng General Rela<vity

Scien<ﬁc impact
1.  Collision of two black holes
2.  FormaHon of a black hole
3.  Most powerful event ever
detected
4.  GravitaHonal waves
5.  UlHmate test of Einstein’s theory

Measuring with an advanced detector

Want to measure a gravita<onal wave?
Laser Beamspliser Mirror
Photodetector
Interference
gas
Seismic
Laser noise
(f,P)
Shot-
noise
RadiaHon
Pressure
noise
Electronic noise

‘Noise hun<ng’

Seismic noise
“ocean peak”
1/f 2 slope
non-quiet day
Spectrum micro-seismic ground motion in Pisa
quiet day
Displacement(m/√Hz)
Frequency (Hz)

Damping with a harmonic oscillator
Frequency (Hz)
Relativeamplitudex/x0(-)
x0
x
L
x0
x
L/2
L/2
1
~ f-4
~ f-2

Horizontal: Inverted Pendulum

Ver<cal: Geometric an<-spring

Components of a seismic isola<on system

mul<SAS prototype at Nikhef

Seismic isola<on system

mul<SAS damping performance
Expected: 10-15 m/√Hz
Required: 10-12 m/√Hz
Horizontal modes in the chain
Takanori Sekiguchi and Kazuhiro Agatsuma

Ultra high vacuum
•  Biggest vacuum in Europe
•  Pressure: 10-10 mbar

Cryotraps
© Marco Kraan / Nikhef

Network of detectors
Fall 2015 Fall 2016 2018 2020
aLIGO
GEO600
KAGRAAdVirgo
IndiGO

KAGRA

KAGRA
©KYODO

Why would you need more detectors?

Sky localisa<on maps for GW150914
Sun
Moon
Sirius
Orion
Carina
Canopus
SMC
View is from the South AtlanHc Ocean, North at the top the Milky Way diagonally from SW to NE

Towards mul<-messenger astronomy
Although no EM radiaHon is
expected from BH merger,
astronomer groups looked

Papers with 1500+ authors!

Einstein Telescope
KAGRA

©NASA

LISA
Armen van 109 m

LISA Pathﬁnder

45|45 J.V. van Heijningen (jvnheijn@nikhef.nl) Thank you!

Back up slides

Frequency [Hz]
Stain sensiHvity [1/√Hz]
What changed from LIGO to aLIGO?

Adding suspended benches for AdVirgo
For the upgrade, laser power is increased
so improved sensing of e.g. mirror angles
at the end of the arms is improved

These sensing opHcs have to be
seismically isolated as well

5 suspended benches are added, shown
here with a blue circle

Damping the horizontal resonances
Ground L4C Geophones (x,z)
Fully digital controls

Sensor correcHon
of diﬀ. sensors by sub-
tracHng ground
noise (feed forward)

Sensor blending of
diﬀ. and absolute
sensor signals

MIMO à SISO
•  9 Sensor inputs
•  3 SISO regulators
•  3 Actuator outputs

Results of SDB2 measurements
Measurement × ProjecHon
Req.
Requirement

Historie van het heelal

Cosmic Microwave Background
Equilibrium in primordial plasma:
ßà for
IonisaHon of hydrogen atoms:
Freeze-out temperatuur
Nu afgekoeld tot T = 2.7255 K
Ayer Tuniverse is low enough, atoms form and photons decouple
Waargenomen door Arno Penzias en Robert
Wilson van Bell Telephone Laboratories in 1965
1978

Fluctua<ons in the CMB

Planck satellite
Planck was launched November 2009

Power spectrum of the CMB
Perfect match with ΛCDM model
Het oerplasma wordt aangeslagen Hjdens inﬂaHe, waarbij er dichtheidsverstoringen met
hoge snelheid door het
plasma gaan. Dat levert
deze pieken

20160503_JVvanHeijningen_GWaperture

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