Measuring H0 with gravitational
wave binary black holemergers and galaxy surveys
Antonella Palmese
7 October 2019
Cosmic Controversies @ UChicago
In Collaboration with DES, LVC, DESI time-domain:
M. Soares-Santos, J. Annis, Z. Doctor, W. Farr, M. Fishbach, J. Gair, J. Garcia-Bellido, W.
Hartley, D. Holz, O. Lahav, H. Lin, I. Magaña Hernandez, S. BenZvi, O. Graur & more

Introduction

Standard sirens
Motivation

Current measurements
Limits/systematics

Prospects

Standard sirens
Motivation

Current measurements
Limits/systematics

Prospects

Schutz 1986Holz & Hughes 2005
MacLeod & Hogan 2008

Standard Sirens

Nissanke+2010
Del Pozzo 2012

DES galaxies

Soares-Santos+DES 2017

Bright standard sirens• Dark standard sirens / statistical methodDark Standard Sirens - why?
DES galaxies

Factor ~10 more BBH events• Will miss some EM counterparts to BNS(and NSBH?)• Further away - can do more than H0•

Soares-Santos+DES 2017

Dark standard sirens - simulations
BCC galaxy simulations (DeRose et al.
2019, Wechsler et al. in prep.)•Simulated GW events in uniform
comoving volume on a galaxy at z with
H0=70 km/s/Mpc•••

Single events: posterior expected tohave peaks corresponding to large scalestructure along the losPeaks are broadened andblended if d or z uncertainty increases.
Converge to the input value of H0from combining enough events

1posterior•d /d = 2%00.2

d /d = 10%

0.00.2d /d = 10%z = 0.013 (1+z)

30.0
50

55

60

65

7075

H0 (km/s/Mpc)

808590Dark standard sirens - simulations••

BCC galaxy simulations (DeRose et al.
2019, Wechsler et al. in prep.)
Simulated GW events in uniform
comoving volume on a galaxy at z with
H0=70 km/s/Mpc

1d /d = 2%

mofr!
tnev

onee

posterioryrgeolmio• Single events: posterior expected toal
msc
have peaks corresponding to large scale is 0.0oc
D o0.2nstructure along the losisicer• Peaks are broadened and0.0pg5055
60
65707580blended if d or z uncertainty iincreases.
noH0 (km/s/Mpc)
dton• Converge to the inputvalue of H0er eventsfrom combiningaenougheW00.2

d /d = 10%

d /d = 10%z = 0.013 (1+z)

38590

Motivation
DES

Prospects
Current measurements
Limits/systematics

GW170814: the golden event (for DES)•••First BBH event LIGO+Virgo: 90% probability
in 60 sq deg
90%+ covered by DECam-GW follow up
Falls in the DES footprint

Doctor, Kessler,
Herner, AP et al. 2018arxiv:1812.01579

See Alyssa Garcia’s poster
on DES-GW follow up

Credit: D.
Brout

GW170814: the golden event (for DES)
•Define a complete volume
limited galaxy sample down
to 4x108 MSun (77% of totalstellar mass) using Year 3data•~77,000 galaxies•

Assumption: event happened
in one of the observed
galaxies, or that it follows theLSS

DES & LVC 2019 arxiv:1901.01540

GW170814 - Results−1+39.5
H0 = 75.2−32.4 km s Mpc−1

GW170814

First measurement of theHubble constant using aBBH
DES & LVC 2019arxiv:1901.01540

LIGO/Virgo O1+O2−1−1
H0 = 68+14kmsMpc−7• LVC 2019 arxiv:

1908.06060 combines all
O1+O2 events• 7% improvement vs170817• Only contribution 170814
Need for complete/deepgalaxy catalogs

Work in progress with Ignacio Magaña Hernandez & others

Systematics/assumptions/limitations
Galaxies

GW• Analysis can be reduced to a study • Gaussianity of d posteriorof the dn/dz in pixels• Marginalization over M
distribution and rate models• Need for complete/deepgalaxy catalogs: sweet spot
between redshift accuracy/
precision and completeness?

Work in progress with Ignacio Magaña Hernandez & others

Systematics/assumptions/limitations
Galaxies

GW• Analysis can be reduced to a study • Gaussianity of d posteriorof the dn/dz in pixels• Marginalization over M
distribution and rate models• Need for complete/deepgalaxy catalogs: sweet spot
between redshift accuracy/precision and completeness?

Conselice, Bhatawdekar, AP &Hartley 2019, arxiv:1907.05361••

Selection function
Galaxy weights:
Depend on BBH formation channels
Stellar evolution (low Z environments,Belczynski+16 )Dynamical interactions (Portegies+00)
PBH (Hawking 71)
AGN disks (Stone+16)
Central BHs of merging ultra-dwarf galaxies

Standard sirensDES

Current measurements
Identify limits/systematics

Prospects

The Dark Energy Spectroscopic
Instrument (DESI)
14,000 sq. deg. over 5 years
0.7M Ly-𝛼 QSOs
1.7M QSOs:
1.0 < z < 3.5

r = 5.0 Gpc/h

z=4r = 4.0 Gpc/h
z=3r = 3.0 Gpc/h

z=2

18M Emission Line
Galaxies (ELGs):
0.6 < z < 1.6z = 1.5

z = 0.7

4M Luminous Red Galaxies (LRGs)
0.4 < z < 1.0r = 2.0 Gpc/h

z=1

Magnitude limited!
z = 0.5

r = 1.0 Gpc/hz = 0.2r = 0.5 Gpc/h

10M bright galaxies (BGS)r < 19.5 (20), z < 0.4

Milky Way Survey: ~10M stars

Dark time

Bright time

The Dark Energy Spectroscopic
Instrument (DESI)
14,000 sq. deg. over 5 years
0.7M Ly-𝛼 QSOs
1.7M QSOs:
1.0 < z < 3.5

r = 5.0 Gpc/h

z=4r = 4.0 Gpc/h
z=3r = 3.0 Gpc/h

z=2

18M Emission Line
Galaxies (ELGs):
0.6 < z < 1.6z = 1.5z = 0.7

4M Luminous Red Galaxies (LRGs)
0.4 < z < 1.0r = 2.0 Gpc/h

z=1Magnitude limited!
z = 0.5

r = 1.0 Gpc/hz = 0.2

r = 0.5 Gpc/h

10M bright galaxies (BGS)r < 19.5 (20), z < 0.4

Milky Way Survey: ~10M stars

Dark time

Bright time

Bright Standard Sirens with DESI
• DESI can help with quick classification, host galaxy redshifts and peculiar velocities• ~2% measurement in ~2023: enough to solve H0 tension - Chen, Fishbach & Holz
2018

AP+DESI time-domain 2019, arxiv: 1903.04730

Prospects for dark standard sirens•••

5% statistical precision with DES-like data and ~100 GW170814-like events~25% of O3 events (33) well localized and covered by DES+DESI imaging
Science that will come for free with DESI nominal targets
AP et al. 2019, arxiv: 1903.04730

100 event sample

DESI-like

760.02540.03
30.10

0.15

0.20

d /d170814,190701,190814,…

DES-likez /(1 + z)

LSST-like

0.01

H0 /H0 (%)

8DES & LVC 2019 arxiv:1901.01540

Conclusions
Other than transient discovery, synergies between
GW experiments and galaxy surveys enable a newcosmological probeLessons from LVC O2:• First measurement of H0 with BBH+DES galaxies• Identified sources of systematics/limitations
Prospects:• Interesting results already from O3 & O4 with upcomingsurveys (DESI, TAIPAN, LSST…)• StSs may help understanding the Hubble constanttension in the near future• Make an impact on targeting for next surveys (e.g. DESI-II)Conclusions
Thank you!
Blahpalmese@fnal.gov

O3 Dark standard sirens withDES+DESI Imaging
DESI Imaging (+WISE):– Dark Energy Camera Legacy Survey (DECaLS)– Beijing-Arizona Sky Survey (BASS)– Mayall z-band Legacy Survey (MzLS)

Photo-zs perform well down to r~21 (DR7, R. Zhou & J. Newman)
25-30% of O3 events well localized and covered by these programs

Prospects for dark standard sirens•••

5% statistical precision with DES-like data and ~100 GW170814-like events~30% of O3 events (33) well localized and covered by DES+DESI imaging
Science that will come for free with DESI nominal targets
AP et al. 2019, arxiv: 1903.04730

100 event sample

DESI-likeDES-likez /(1 + z)

LSST-like0.01

760.02
5H0 /H0 (%)

840.0330.10

0.150.20

d /d170814,
190701,190814,…

Other science cases: hostgalaxy studies tounderstand origin of GW
sources (e.g. AP+17 1710.06748,
Scelfo+19, 1809.03528)

DES & LVC 2019 arxiv:1901.01540

The Dark Energy Survey (DES)••First/last light: 12-12-12 / 01-08-19
300M galaxies over 5000 sq. deg.

DECam follow-up continues

DECamPremier instrument for GW optical follow up inthe Southern hemisphere
3 sq deg FOV, 570 Mpix optical CCD camera
CTIO Blanco 4-m telescope (Chile)9060

300300Declination

1550.23083.0115.8

45Public data

60

https://des.ncsa.illinois.edu/home
150

1209060
300Right Ascension

3060

90

DR1 (Y3) - 400M objects (r~24)

The Dark Energy Spectroscopic
Instrument (DESI)• 5000-fiber spectrograph on Kitt

Peak Mayall 4m Telescope (AZ)
• 8 deg2 FoV• Stage-IV BAO/RSD DE experiment• 14,000 sq. deg. over 5 years• Starting SV in Feb 2020
• Bright Galaxy Sample: maglimited sample of 10M galaxies (r <19.5, z < 0.4)

DESI timeline
2013

2017

2015

2019

2021

2023

2025

2027

2029

BOSSDESHETDEXHSCPFS Spec

Stage IIIeBOSSCI
DESI Imaging

Science Verification (Feb 2020)
DESI

Stage IVDESI II?

Survey (June 2020-2025)
Commissioning
LSST
EuclidImaging
Spectroscopy

WFIRSTDark standard sirens with DESI BGS
Science that will come for free with DESI nominal targets•

4-5% statistical precision with DES-like data and ~100 GW170814-like events

100 event sample

DESI-like

DES-likez /(1 + z)

LSST-like

0.01

760.02
5

H0 /H0 (%)

840.03
30.10

0.15

0.20

d /d170814,190701,190814,…

Other science cases
include host galaxy studies
to understand origin ofGW sources (e.g.
Scelfo+2019, 1809.03528)

DES & LVC 2019 arxiv:1901.01540

SDSS+eBOSS
Overdensities
Underdensities
160k Ly-𝛼 QSOs
500k QSOs:
z < 3.5

1210
86175k Emission LineGalaxies (ELGs):
0.6 < z < 1.1

42L

kooe(libnolitim s)
k arcba ye
1.5M Luminous Red Galaxies (LRGs)z < 0.7

Prospects for current detectorsDARK ENERGYSURVEY•

Few % measurement in ~2022 from bright sirens: enough to solve H0 tension•Dark sirens from BBH worse. Need more well-localized events•

NSBHs can provide competitive constraints, if rate >1/10 BNS (Vitale & Chen 2019, PRL)

~10% BBH~5% BNS (no EM)
NSBH?

~1% BNS

Chen, Fishbach & Holz
2018, NatureImpact on full cosmology
DARK ENERGYSURVEY•••

Combining upcoming GW H0constraints + future CMB +BAO significantly improves
constraints beyond ΛCDM
Breaks geometricaldegeneracies between
parameters from CMB
Factor 1.6-2.8 improvement
on dynamical DE parameters

ΛCDM + Ωk + Σmν + w0 + wawaΩkΣmν

H0w0waΩkΣmν

H0Di Valentino, Holz, Melchiorri, Renzi 2018