3rd generation GW observatories: Science potentialities ...static.sif.it/SIF/resources/public/files/congr10/mc/punturo.pdf · Continuous Wave (CW) emission of isolated NS. Binary

Michele PunturoINFN Perugia and EGOOn behalf of the Einstein Telescope Design Study Teamhttp://www.et-gw.eu/

1SIF - Bologna 2010

3rd generation: Why ? Evolution of the GW detectors (Virgo example):

2003

Infrastructure

realization and

detector assembling

2008

Sameinfrastructure

Proof of the working principle

Upper Limit physics

2011

enhanceddetectors

Sameinfrastructure

2017

Sameinfrastructure

First detection

Initial astronomy

2022

SameInfrastructure

(≥20 years old for Virgo, even more for LIGO & GEO600)

Precision Astronomy

Cosmology

2

SIF

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010

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year

Beyond Advanced Detectors GW detection is expected to occur in the advanced detectors. The 3rd generation

should focus on observational aspects: Astrophysics:

Measure in great detail the physical parameters of the stellar bodies composing the binary systems NS-NS, NS-BH, BH-BH Constrain the Equation of State of NS through the measurement

of the merging phase of BNS of the NS stellar modes of the gravitational continuous wave emitted by a pulsar NS

Contribute to solve the GRB enigma Relativity

Compare the numerical relativity model describing the coalescence of intermediate mass black holes

Test General Relativity against other gravitation theories Cosmology

Measure few cosmological parameters using the GW signal from BNS emitting also an e.m. signal (like GRB)

Probe the first instant of the universe and its evolution through the measurement of the GW stochastic background

Astro-particle: Contribute to the measure the neutrino mass Constrain the graviton mass measurement

3

SIF - Bologna 2010

Target Sensitivity Target sensitivity of a new, 3rd generation “observatory”

(the Einstein Telescope, ET) is the result of the trade off between several requirements

SIF - Bologna 2010 4

1. Science targets2. Available technologies (detector realization)3. Infrastructure & site costs

1. Infrastructure & site costs2. Available technologies (detector realization)3. Science targets

As starting point of our studies we defined two rough requirements: Improvement by a factor 10 the advanced sensitivities Access, as much as possible, to the 1-10Hz frequency

range Let see the new possibilities open by such as observatory

Binary System of massive stars

The new possibilities (for BS) of a 3rd generation GW observatory emerge from these two plots: Cosmological detection distance Frequent high SNR events


Cosmological detection distance BNS are considered “standard sirens” (Schutz 1986)

because, the amplitude depends only on the Chirp Mass and Luminosity distance DL


Hence, through the detection of the BNS gravitational signal, by a network of detectors, it is possible to reconstruct the luminosity distance DL be solved by only using GW detectors

The masses can be determined by matching the signal with a bank of templates, the position using a network of detectors

DL⇒ DL (1+z) ω ⇒ ω/(1+z) Mc⇒ Mc (1+z)

But the ambiguity due to the red-shift (red-shifting of the GW frequency affects the reconstructed chirp mass and then the reconstructed DL) cannot be solved by only using GW detectors

Gamma Ray Bursts The red-shift ambiguity

requires an E.M. counterpart (GRB) to identify the hosting galaxy and then the red-shift z.


ΩM: total mass densityΩΛ: Dark energy densityH0: Hubble parameterw: Dark energy equation of state parameter

Knowing DL and z it is possible to probe the adopted cosmological model:

Cosmology with ET Cosmology measurements have been proposed combining the

Plank CMB measurement with the SNAP* Universe expansion SNe are standard candles, but they need for “calibration” (Cosmic

Distance Ladder)

SIF - Bologna 2010 8*SNAP: SuperNova Acceleration Probe (JDEM)

Cosmology with ET Cosmology measurements have been proposed combining the

Plank CMB measurement with the SNAP* Universe expansion SNe are standard candles, but they need for “calibration” (Cosmic

Distance Ladder) Thanks to the huge detection range of a 3rd generation GW

observatory and the consequent high event rate (~106 evt/year) it has been evaluated for ET (Sathyaprakash 2009) a capability to constrains the cosmological parameters using CMB+GW similar to what is feasible with CMB+SNe, but without any need of Cosmic Distance Ladder


*SNAP: SuperNova Acceleration Probe (JDEM)

High SNR signals


ET Restricted

ET Full

Van Den Broeck and Sengupta (2007)

ET FullET Restr.

Access to all the three phases of the coalescence with high SNR: Early inspiral phase

Restricted Post-Newtonian (PN) modeling Plunge phase

Full PN (higher harmonics!) approximation Numerical Relativity (NR) templates Equation Of State (EOS) modeling

Merger or Ring-down phase Numerical Relativity modeling Quasi-Normal modes simulation & EOS constrains

Modeling quality is crucial: Higher harmonics:

Improved BNS parameters determination Improved (or “simplified” sky location of the BNS source) Enrichment of the higher frequency content of the BS emission:

Intermediate mass black holes within the detection band of terrestrial detectors

ET: Numerical Relativity test bench PN approximations fails close to the plunge/merging phase

(large v/c): Hybrid templates


PN NRPN/NR overlap

Ajith et al. CQG 2007Ajith et al. PRD 2008

But the PN component of the hybrid template it is still source of error, marginally detectable in the advanced detectors (small SNR) but probably dominant in ET

Santamaria et al., PRD2010

Need for better PN approx or longer NR simulation

Neutron Stars (NS) The EOS of the NS matter is still unknown

Why it pulses? It is a neutron or a “strange” matter star?


What is the role of the Magnetic field in a NS?

GW could investigate the NS EOS detecting the signal produced in different processes: Coalescence of binaries

Full NR simulation of the plunge and merger phase

Asteroseismology Detecting the internal modes

of the NS Continuous Wave (CW) emission

of isolated NS

Binary NS coalescence The Binary System coalescence has been already

described in the previous slides, here the importance of the NR for BNS is stressed


BH+BH BH + GWsNS+NS HMNS + GWs BH + GWs+…?

EOS understandingis crucial

Role of the magnetic field? Relativistic magnetized hydro-

dynamics simulation (L.Rezzolla 2010)

Only ET promises to reveal the effects of B

Continuous Wave The ET improved sensitivity could boost

the GW detection from a pulsar


Continuous Waves in ET Minimal detectable ellipticity ε could approach levels

interesting to distinguish the core characteristics Solid cores could sustain ε up to 10-3; Crust could sustain ε up to 10-6 -10-7;


Minimum detectable ellipticity for known pulsars

10-10

10-8

10-6

10-4

10-2

ε

Supernova Explosions Mechanism of the core-collapse SNe still unclear

Shock Revival mechanism(s) after the core bounce TBC


GWs generated by a SNe should bring information from the inner massive part of the process and could constrains on the core-collapse mechanisms

SNe rates with ET Expected rate for SNe is about 1 evt / 20 years in the detection range

of initial to advanced detectors Our galaxy & local group


Distance [Mpc]

To have a decent (0.5 evt/year) event rate about 5 Mpc must be reached

ET nominal sensitivity can promise this target

Distance [Mpc]

[C.D. Ott CQG 2009]

Neutrinos from SNe SNe detection with a GW detector could bring additional info:

The 99% of the 1053 erg emitted in the SNe are transported by neutrinos

If a “simultaneous” detection of neutrinos and GW occurs the mass of the neutrino could be constrained at 1eV level (Arnaud 2002)


But looking at the detection range of existing neutrino detectors (<Local group limited) is discouraging

Some promising evaluation has been made (Ando 2005) for the next generation of Megaton-scale detectors

Ando 2005

The Einstein Telescope The Einstein Telescope project is currently in its

conceptual design study phase, supported by the European Community FP7 from May 2008 to July 2011.

ASPERA-SAC, Apr201019

Participant Country

EGO ItalyFrance

INFN Italy

MPG Germany

CNRS France

University of Birmingham UK

University of Glasgow UK

Nikhef NL

Cardiff University UK

CNRS; 17

CU; 4

EGO; 13

INFN; 57

MPG; 33

UNIBHAM; 9

UNIGLASGOW; 33

VU; 7

Participants per Beneficiary

0 1 2 3 4 5 6 7 8 9

British Astromomical AssociationCALTECH

CERNCork University

Dearborn observatory (NorthWestern …Deutsches Elektronen-SynchrotronFriedrich-Schiller-Universität Jena

Hungarian Academy of scienceKFKI Research Institute for Particle and …

LIGOMIT

Moscow State UniversityNicolaus Copernicus Astronomical Center

Raman research instituteThe Royal Observatory

Tuebingen UniversityUniversità degli Studi di Trento

Universitat Autonoma de BarcelonaUniversiteit Van Amsterdam

University of MinnesotaUniversity of Southampton

Washington State University

Participants per NON-Beneficiary

Targets of the Design Study Evaluate the science reaches of ET Define the sensitivity and performance requirements

Site requirements Infrastructures requirements Fundamental and (main) technical noise requirements Multiplicity requirements

Draft the observatory specs Site candidates Main infrastructures characteristics Geometries

Size, L-Shaped or triangular Topologies

Michelson, Sagnac, … Technologies

Evaluate the (rough) cost of the infrastructure and of the observatory

ASPERA-SAC, Apr2010 20

http://www.iconspedia.com/uploads/632613165.png



How ET goes beyond the 2nd generation?


10-25

10-16

h(f)

[1/s

qrt(H

z)]

Frequency [Hz]1 Hz 10 kHz

Seismic

Very Low Frequency Appealing for “massive objects (IMBH)” and CW from

NS Two related obstacles:

Seismic noise Gravity gradient noise (induced by seismic noise)

Virgo already implements the status of the art in seismic filtering … difficult to do largely better We need to reduce the seismic noise

1. Go in the space2. Go on the Moon3. Go underground !!!


Underground Seismic noise Measurement


Seismic filtering Test on the Virgo Super-Attenuator

Pre-filtering (IP) neglected


Additional noise subtraction schemes under study

Gravity Gradient Noise reduction An underground site permits also to suppress the GGN

influence


Surface

-10 m

-50 m

-100 m

-150 m

ET-B

ET-C

G. Cella 2009

The current level of understanding of the seismic noise related limitation indicatesthat the selection of a quiet site, at about 100m deepness, adopting a filtering system “à la Virgo” about 17 m tall, is compliant with the most stringent ET requirements (ET-C) starting from about 3Hz

New (~10km arm length)infrastructure!!!

Cryogenics Thermal noise reduction (middle range frequency) requires

a big “jump” Optimization of the dissipations (Fluctuation-dissipation

theorem) progresses are probably saturated Best substrates selected for advanced detectors Coating progresses expected to be “limited” Difficulties in further increasing the beam radius (LG modes) Monolithic fused silica suspensions close to the best achievable


Need to profit of the equi-partition theorem: Cryogenics Direct reduction of the thermal noise New materials needed (Si, Al2O3,…) New optoelectronics needed New infrastructures needed

High frequency High frequency noise reduction requires the

suppression of the quantum noise


Shot noise reduction

Brute force approach: High power in the FP cavities High power laser High reflectivity Thermal lensing issues Parametric instabilities Difficult cross-compatibility with

cryogenics

QND techniques: squeezing Promising (10dB in lab), tests

starting now Frequency dependent

implementation New infrastructures

ET sensitivity (sensitivities) Implementing all the technologies under study for ET a

target sensitivity (ET-B) can be draft


Doubts on the cross-compatibility of the technologies

Need to simplify the problem Xylophone

strategy

New infrastructure A 3rd generation GW observatory is a must for the GW

community to consolidate a new era for the GW astronomy


We need to develop new technologies for our interferometers to go beyond the advanced detectors

But, as first priority, we need new infrastructures to host the GW observatories for decades

The first lesson we learned is that the new infrastructure must be hosted in an underground site

We are compiling the list of candidate sites But, what about the geometry of the new infrastructure?

Geometry optimization


L L

45°

Fully resolve polarizations

5 end caverns4×L long tunnels

45° stream generated by virtual interferometry

Null streamRedundancy

7 end caverns6×L long tunnels

60°

L’=L/sin(60°)=1.15×L

Fully resolve polarizations by virtual interferometry

Null streamRedundancy

~3-9 end caverns3.45×L long tunnels L

Equivalent to

(Freise 2009)

The infrastructure Schematic view

ASPERA-SAC, Apr2010 31

Full infrastructure realized Initial detector(s)

implementation 1 detector (2 ITF) Physics already

possible in coincidence with the improved advanced detectors

Progressive implementation 2 detector (4 ITF) Redundancy and cross-

correlation Full implementation

3 detector (6 ITF) Virtual interferometry 2 polarizations

reconstruction

The ET project The target of the ET project is to realize in Europe a

fundamental Research Infrastructure that could host the Gravitational Wave observatories for decades, opening the GW precision astronomy and implementing the technical evolutions in the detectors composing the observatory

The implementation of the full observatory is diluted in the years and triggered by the first detection

Similar efforts are currently starting in US


Documents

3rd generation GW observatories: Science potentialities ...static.sif.it/SIF/resources/public/files/congr10/mc/punturo.pdf · Continuous Wave (CW) emission of isolated NS. Binary