Gravitational-Wave Cosmology with Standard Sirens

Martin Hendry

Institute for Gravitational Research SUPA School of Physics & Astronomy University of Glasgow, UK LIGO Scientific Collaboration

Abilene Christian University Albert-Einstein-Institut Northwestern University American University Penn State University Andrews University Rochester Institute of Technology Bellevue College Sonoma State University California Institute of Technology Southern University California State Univ., Fullerton Stanford University California State Univ., Los Angeles Syracuse University Texas Tech University Canadian Inst. Th. Astrophysics Carleton College Trinity University Chinese University of Hong Kong Tsinghua University College of William and Mary U. Montreal / Polytechnique Colorado State University Université Libre de Bruxelles Columbia U. in the City of New York University of Chicago Cornell University University of Florida Embry-Riddle Aeronautical Univ. University of Maryland Eötvös Loránd University University of Michigan Georgia Institute of Technology University of Minnesota Goddard Space Flight Center University of Mississippi GW-INPE, Sao Jose Brasil University of Oregon Hillsdale College University of Sannio Hobart & William Smith Colleges University of Szeged IAP – Nizhny Novogorod University of Texas Rio Grande Valley IIP-UFRN University of the Balearic Islands Kenyon College University of Tokyo Korean Gravitational-Wave Group University of Washington Louisiana State University University of Washington Bothell Marshall Space Flight Center University of Wisconsin – Milwaukee Montana State University USC – Information Sciences Institute Montclair State University Villanova University Moscow State University Washington State University – Pullman National Tsing Hua University West Virginia University NCSARG – Univ. of Illinois, Urbana- Whitman College Champaign LIGO Laboratory: California Institute of Technology; Massachusetts Institute of Technology; LIGO Hanford Observatory; LIGO Livingston Observatory

Australian Consortium for Interferometric Gravitational Astronomy (ACIGA): Australian National University; Charles Sturt University; ; Swinburne University; ; ; University of Western Australia

German/British Collaboration for the Detection of Gravitational Waves (GEO600): Albert-Einstein-Institut, Hannover; Cardiff University; King's College, University of London; Leibniz Universität, Hannover; University of Birmingham; University of Cambridge; University of Glasgow; University of Hamburg; University of Sheffield; University of Southampton; University of Strathclyde; University of the West of Scotland; University of Zurich

Indian Initiative in Gravitational-Wave Observations (IndIGO): Chennai Mathematical Institute; ICTS-TIFR Bangalore; IISER Pune; IISER Kolkata; IISER-TVM Thiruvananthapuram; IIT Madras, Chennai; IIT Kanpur; IIT Gandhinagar; IPR Bhatt; IUCAA Pune; RRCAT Indore; University of Delhi

Gravitational Waves: the Story So Far

In General Relativity gravity is described by the curvature of space-time

Matter tells spacetime how to curve. Spacetime tells matter how to move

Gravitational waves are ripples in spacetime propagating at the speed of light (according to GR)

Created by acceleration of massive compact objects

Gravitational wave detectors measure changes in L-L the separation between free test masses in this spacetime

L+L

GravitationalGeneral Waves: Relativity/Gravity the Story Waves So Far

Gravitational waves are generated by accelerating masses. We need large masses (e.g. neutron stars/black holes) moving close to the speed of light

M = 1.4 Msun f=1kHz R=2m f = 200 Hz

h ~ 10-21 @ 100 Mpc

At 300m: h=10-37 Low mass, low speed Large mass, large speed

Terrestrial source Astrophysical source

Interferometric Detectors

Interferometers monitor the position of suspended test masses separated by a few km

A passing gravitational wave will lengthen one arm and shrink the other arm; transducer of GW strain- intensity (10-18 m over 4 km)

10-5m

41016m Ground-based network of detectors: 2002-2010

LIGO GEO600 Hanford TAMA, CLIO 300 m 600 m 4 km 100 m 2 km

LIGO LIGO VIRGO 3 km LivingstonLivingston

4 km Upgrading for the Advanced Detector Era!... From Initial to Advanced LIGO 10kg test masses on simple pendulums become 40kg monolithic suspensions in quadruple pendulums, with better quality optics Developed in Glasgow, UK supplied: fused silica suspensions, fibre-pulling, bonding and welding

GW150914 – a burst of gravitational waves… … matching a BBH inspiral and merger waveform from General Relativity

Abbott et al (2016): https://dcc.ligo.org/P1500218/ BBH detections announced to date

First Observing run Second Observing run Abbott, et al., LIGO Scientific Collaboration and Virgo Collaboration, “GW170104: Further tests of General Relativity Observation of a 50-solar binary black hole coalescence at redshift 0.2” Phys. Rev. Lett. 118, 221101 (2017) Parameterised test of PN expansion

Modified dispersion relation

Lower limit on QG energy scale BBH detections announced to date

First Observing run Second Observing run With three or more interferometers we can triangulate the sky position of a gravitational wave source much more precisely.

Source location

Advanced Virgo joined O2 on Aug 1st 2017

Much better From Aasi et al. sky localisation arXiv:1304.0670

Abbott et al., Astrophys. J. Lett. 848, L13 (2017) Cosmology with Standard Sirens

Schutz, Nature, 323, 310 (1986) Dalal et al. (2006)

• Considered joint GW-EM observation of short GRBs

• 4-detector network including AIGO • sGRBs modelled as beamed (→ nearly face-on) versus isotropic

Beamed • Assume redshift from Isotropic EM counterpart (or host galaxy)

• Measure h (and w from CMBR)

• Fisher matrix: Nissanke et al, arxiv:0904.1017 h to ~3% from 10 joint GW-GRB observations

Dalal et al, PRD, 74, 063006 (2006) Tension between:

1. Measurement of H0 from cosmic distance

ladder (e.g. SH0ES)

2. Inference of H0 from CMBR / LSS and cosmological model (e.g. Planck 2015)

W. Freedman, arxiv:1706.02739 Abbott et al. Nature, 551, 85 (2017) Abbott et al. PRL, 119, 161101 (2017) Observables:

• = GW170817 distance

• = recession velocity

• = mean pec. velocity

Abbott et al. PRL, 119, 161101 (2017) Observables:

• = GW170817 distance

• = recession velocity

• = mean pec. velocity

Observables:

• = GW170817 distance Assuming optical counterpart in NGC 4993, • = recession velocity and at true sky location of BNS…

• = mean pec. velocity

Recessional velocity of CoM of galaxy group Abbott et al. Nature, 551, 85 (2017) Observables:

• = GW170817 distance

• = recession velocity

• = mean pec. velocity

Recessional velocity of CoM of galaxy group Abbott et al. Nature, 551, 85 (2017) Reconstructed from 6dF and 2MASS galaxy redshift surveys.

Observables:

• = GW170817 distance

• = recession velocity

• = mean pec. velocity

Springob et al. MNRAS, 445, 2677 (2017)

Carrick et al. MNRAS, 450, 317 (2015) Reconstructed from 6dF and 2MASS galaxy redshift surveys.

Observables:

-1 Assumes = 0.42 Allows for 150 kms uncertainty • = GW170817 distance on bulk flow reconstruction

• = recession velocity

• = mean pec. velocity

“Master” equation Maximum minimal posterior value 68% C.I.

Abbott et al. Nature, 551, 85 (2017) Maximum minimal posterior value 68% C.I.

Abbott et al. Nature, 551, 85 (2017) Abbott et al. Nature, 551, 85 (2017) Can we constrain the inclination from EM observations?

Guidorzi et al. model broad-band emission, from X-ray and radio, for an off-axis jet.

How robust are these assumptions?... (c.f. Piran et al. 2017 – GRB cocoon model)

Guidorzi et al, arxiv:1710.06426 Coming attractions…

Abbott et al, arxiv:1304.0670 Coming attractions…

Are these rates compatible with beaming?

What about the (more) isotropic emission from e.g. a kilonova?

Nissanke et al, arxiv:1307.2638

Finding the E-M counterpart…

observatory.org/

- http://goto

http://www.lsst.org/lsst/

Metzger & Berger 2012 Third Generation GW Network

Aimed at having excellent sensitivity from ~1 Hz to ~104 Hz.

FP7 European design study, with EU funding, for a 3rd-generation gravitational wave facility, the Einstein Telescope (ET).

Goal: 100 times better sensitivity See also Dwyer et al. arxiv: 1410.0612 than first generation instruments.

See www.et-gw.eu

Sathyaprakash et al. CQG, 29, 2, 914013 (2012) arxiv: 1108.1423 Cosmological constraints from Fit , , 3G detectors Competitive with Sathyaprakash et al. (2009): ‘traditional’ methods ~106 NS-NS mergers observed by ET. Assume that E-M counterparts observed Weak lensing De-lensed for ~1000 GRBs, 0 < z < 2.

Sirens weakly lensed by intervening LSS

Assume can be ‘de-lensed’, using e.g. cosmic shear maps. Correcting for Weak Lensing?...

Shapiro et al (2010): No correction

Shear varies from place to place. Shear map only, ELT

Gradient of shear → arcing, or flexion

Shear + flexion, Shear + flexion, ELT ELT + Space

Assume we can measure flexion from galaxy surveys, giving better estimate of matter density on small angular scales.

 DL → 1.8% at z  2

 DL → 1.4% at z 1 Euclid EELT

40 Cosmological constraints from 3G detectors Zhao et al. (2011) [See also Zhao & Wen in prep.]

~106 NS-NS mergers observed by ET.

Different models for spatial distribution, source evolution; more general DE models

z w(z)  w0  wa 1 z

GW constraints similar to those from BAO, SNIe.

Results only weakly affected by source evolution.

BUT assumes z known for ~1000 sources

Significant ‘multi-messenger’ challenge

Howell et al. MNRAS in press (2018) The Gravitational Wave Spectrum Supernovae Cosmic Strings BH and NS Binaries Relic radiation

Extreme Mass Ratio Inspirals

Supermassive BH Binaries Binaries coalescences Spinning NS

10-16 Hz 10-9 Hz 10-4 Hz 100 Hz 103 Hz Inflation Probe Pulsar timing Space detectors Ground based

Adapted from M. Evans (LIGO G1300662-v4) z 1 LISA offers high-precision luminosity distances from SMBH mergers observed at significant redshift.

BUT weak lensing scatter still a significant issue (even more so than for ground-based as event rate may be much lower…)

Read more at https://www.elisascience.org/

Adapted from Holz & Hughes (2005) z 1 LISA offers high-precision luminosity distances from SMBH mergers observed at significant redshift.

BUT weak lensing scatter still a significant issue (even more so than for ground-based as event rate may be much lower…)

Read more at https://www.elisascience.org/

Adapted from Holz & Hughes (2005) Some coming attractions?.... • Improved tests of GR:

 P-N orders; Compton wavelength  polarisation constraints  speed of gravity – EM arrival, dispersion  EMRI mapping spacetime around SMBHs  joint GW-EM observations of lensed sources • Constraining non-standard cosmologies:

 Hubble diagram of sirens; event rates  Primordial BHs – constrained from spin distribution  Strong lensing by DM haloes: constraints on cores?  ????