Science Briefing10/23/2019

Hubble Constant Discrepancies –

Implications for

Our Expanding Universe

Dr. Wendy Freedman (Univ. of Chicago)

Dr. Charles Lawrence (JPL, Caltech)

Dr. Adam Riess (JHU, STScI)

Facilitator: Dr. Chris Britt (STScI) 1

1. Dr. Wendy Freedman (Univ. of Chicago)Tension in the Hubble Constant

2. Dr. Charles Lawrence (JPL, Caltech)

H0 from the CMB

3. Dr. Adam Riess (JHU, STScI)

The Expansion of the Universe, Faster Than We Thought

4. Q&A

5. Dr. Christopher Britt (STScI)

Education Resources

6. Q & A

Outline of this Science Briefing

2

+NASA's Universe of

Learning Science Briefing

Wendy Freedman

October 23, 2019

Tension in the Hubble Constant

3

Lemaitre

Robertson

Hubble

Oort Baade ***

History

Hubble

Key

Project

4

+ Hubble’s Sister Satellite:

The Spitzer Space Telescope

Image credit: NASA/JPL-Caltech5

The Current Tension in H0

Updated from WLF et al., 2017

The Current Tension in Ho

Distance Ladder CMB

The Current Tension in Ho

W. Freedman

6

The Current Tension in H0

Updated from WLF et al., 2017

The Current Tension in Ho

Distance Ladder CMB

The Current Tension in Ho

W. Freedman

7

The Current Tension in H0

Updated from WLF et al., 2017

The Current Tension in Ho

Distance Ladder CMB

The Current Tension in Ho

W. Freedman

8

The Current Tension in H0

Updated from WLF et al., 2017

The Current Tension in Ho

Distance Ladder CMB

The Current Tension in Ho

W. Freedman

9

The Current Tension in H0

Updated from WLF et al., 2017

The Current Tension in Ho

Distance Ladder CMB

4.4 σ

The Current Tension in Ho

W. Freedman

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+NGC 1448 NGC 1365M101

Credits: NASA, ESA, W. Freedman (University of Chicago),

ESO, and the Digitized Sky Survey

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+NGC 1448 NGC 1365M101

M101

Credits: NASA, ESA, W. Freedman (University of Chicago),

ESO, and the Digitized Sky Survey

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+ A New Determination of the Hubble

Constant

120 CSP SNe Ia24 calibrators

Show TRGB separately

Dis

tan

ce

Velocity

Distant SupernovaeNearby Cepheids and Red Giants Distant Supernovae

Red Giants

Dis

tan

ce

Velocity (redshift)

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+ Ho Values With Time

P18?

WLF et al. (2019, ApJ)14

Recent published H0 Values

15

+

Systematic

Errors

Statistical errors are well

defined

Systematics are the challenge

Independent groups are now

working on this issue from

many different angles

Resolution of this issue should

be forthcoming in next

several years

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+

CMB

Excellent fit of

the standard model (”Lambda Cold Dark Matter – ΛCDM) to current

microwave background

data

Near-term future

measurements promise

to rule --in or out –

current proposals for

new physics

17

+

Theory

Theorists are working

hard to try and come up

with theoretical models

that can explain the early

and late universe

measurements

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10/15/2019, 17*58c8c4c802- 4b76- 49da- b80a- 0 fb8d02c62b7 2,095×1,242 pixels

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H0 from the CMB

C

C. R. Lawrence, JPLNASA Universe of Learning

Science Briefing23 October 2019

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The CMB

• The cosmic microwave background (CMB) is the oldest light in the Universe.

• It was emitted 13.8 billion years ago, about 370,000 years after the Big Bang

• It is the 3000-K glow of the ionized, opaque early Universe, emitted just as the matter cooled enough to form stable, neutral hydrogen and helium, and therefore became transparent.

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10/15/2019, 17*58c8c4c802- 4b76- 49da- b80a- 0fb8d02c62b7 2,095×1,242 pixels

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The Magic of the CMB

• The CMB

can be accurately measured,

and compared to precise theoretical predictions with a rich phenomenology,

in a statistically reliable

and computationally tractable way.

There are very few situations in cosmology, astrophysics, or indeed physics where all of these conditions are met.

It is the intersection of these qualities that makes the CMB such a powerful cosmological probe.

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Superposition of Sound Waves 10/15/2019, 17*58c8c4c802- 4b76- 49da- b80a- 0fb8d02c62b7 2,095×1,242 pixels

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https://www.cosmos.esa.int/documents

Matter Density & Sound Speed

• The statistical properties of the map are fitted amazingly well by a six-parameter

cosmological model.

• The six parameters are:

• The density of “normal” matter

• The density of “dark” matter

• The amplitude and slope of the spectrum of initial fluctuations 10-32 s after the

Big Bang

• The angular scale of the measured fluctuations

• The fraction of CMB photons scattered by reionized matter in their 13.8-

billion-year journey to us

• The density of normal matter determines the speed of sound, …

• …which determines how far sound can travel in 370,000 years, …

• …which we see as the angular scale of the measured fluctuations

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Planck 2018 results. I.

From Matter Density to H0

Distance sound travels in

370,000 years. Depends on

the density of normal matter,

which Planck determines

from the CMB to better than

1%.

We have a physical length,

and the angle subtended by

that length. Can calculate the

distance to where the CMB

photons came from. That

gives H0.

Angle subtended by that distance, which Planck determines

from the CMB to 0.03% !

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We get H0 = 67.4 ± 0.5 km/s/Mpc

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Planck 2018 results. VI.

Comments

• Determination of H0 is not the goal of CMB observations, but rather one of many results that are consequences of the determination of the overall cosmological model.

• Is the model correct? That’s not really the right way to frame the question. The model fits the data extremely well, with uncertainties on five of six parameters less than 1%. Many other models have been tried. None so far fits the data better (by the usual standards of data-fitting).

• Models with additional parameters can be devised that have higher values of H0, but generically when H0

increases, something else goes wrong.

• H0 is tightly constrained by the whole universe.

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The Expansion of the Universe,

Faster Than We Thought

Johns Hopkins University

Space Telescope Science Institute

Review: Verde, Treu, Riess 2019, NatAs,3,891

SH0ES Team: Riess+2019, ApJ, 876, 8527

The Standard Model of Cosmology Emerges: Early 2000’s

Big

Bang

supernovae

spots from Big Bang

Now

Dark Energy

70%

Atoms

(stars,etc),

5%

Standard

Candles

(supernovae)

Big Bang

Afterglow

Late

Universe

side

Early

Universe

side

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SH0ES Project: Improve calibration of H0 w/ Distance Ladder

Anchors:

Milky Way or just Beyond

D~thousands of Lyrs

Geometry

(5 ways) Cepheids (pulsating stars)

Hubble Flow:

Distant Galaxies

D~a few Billion Lyrs

Supernova Ia Redshifts

Cross-calibrate:

In nearby Galaxies

D~50-100 Million Lyrs

Cepheids (pulsating stars)Supernova Ia

(2005)

1

2

3

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Better MeasurementsEra of Precision Cosmology, 2000-present, Improving Measurements

Improved Resolution

of Big Bang afterglow

Same model, refined composition

Factor of 5

improvement

present

expansion rate

(Hubble

constant)

using Hubble

Space

Telescope

from 10% to

2% uncertainty

1970 1980 1990 2000

40

HU

BB

LE

CO

NS

TAN

T

(KM

S-1

MP

C-1

)

80

60

73.5

± 1.4

Km/s/Mpc

Hubble Space Telescope

(Riess et al. 2019)

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Late Universe H0 (KITP 2019) Review by Verde, Treu, Riess (2019)

Nature Astronomy *

Naïve Combo: 73 +/- <1 but

some overlap so…

Late Universe

Prix Fixe Menu

---------------------------

One from 1

+ One from 2

+3

+4

- one peremptory

challenge

*includes 7th lens from Shajib+2019

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Late Universe H0 (KITP 2019)

Late Universe

Prix Fixe Menu

---------------------------

One from 1

+ One from 2

+3

+4

- one peremptory

challenge

32

The Tension Matrix—present difference is 4-6 times the error bars

E

A

R

L

Y

LATE UNIVERSE (Methods)

(Lower )

(Low

er

)

TRGBCepheids

No

SNNo

lens

Mira

s

33

The Expansion Rate Conundrum, Problem or Opportunity?

Big

Bang

How old

is the

universe?

What are we

missing?

Standard

Candles

Big Bang

Afterglow

Late

Universe

side

Early

Universe

side

34

State of the Universe-half full or half empty?

Dark

Energy

?

25%

?

70%

Gas 4%Stars 0.5%

Planets

0.05%

Planets+

Stars+Gas

The Standard Model of Cosmology, ΛCDM

Evidence of A New Feature in the Universe?

Dark matter interactions? Growing dark energy? A new

light particle? An earlier episode of dark energy?

Exciting times! More data needed!

Tensions in the Model!Cosmological “Rashomon”

35

2018: NASA moves to Phase B development for WFIRST2012: NRO gives NASA 2, 2.4m space telescopes…2011: ESA selects Dark Energy as next mission, EUCLID2010: NAS Decadal Survey Picks, WFIRST, JDEM design

WFIRST—Wide Field InfraRed

Survey Telescope

•2.4m, wide angle

•Dark Energy via 3 methods

•Planet finder, surveyor

Space Telescopes Being Designed to Study Dark Energy—2020-2025

The Goal: To measure if dark energy evolving & if General

Relativity (Einstein’s theory) works on large-scales.

Other New Facilities: Gravitational waves, JWST, Survey Telescopes36

• 95% of the Universe is dark and we don’t understand it!

• Understanding it will reveal the fate (origin) of the Universe

• Touches the central pillars of modern physics (QM, GR, String) It’s

a clue and embarrassment (a 10120 error for cosmological constant!).

It is likely to lead to something interesting…

WHY STUDY THE DARK UNIVERSE?

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Early Late

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• Beyond the Headlines:Mystery of Cosmic Expansion Deepens

• Did You Know:The Universe is Expanding

• Did You Know:The Fate of the Universe

• At a Glance: There’s More than One Way to Destroy a Star—Types of Supernova

Additional Resources

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• Activity guide “The Hubble Constant: Playing with Time”

• Soon to be posted on universe-of-learning.org

• Supernova Educator’s Guide: A collection of activities, games, and lessons about supernovae, each tied to National Science Education Standards.

• Big Bang Science Fiction:

Additional Resources

40

• WMAP “Build a Universe”

• Planck mission informal education resources

• Image and video resources for WMAP

• WMAP Science Concept animations

Additional Resources

41

• Cosmology articles on Hubblesite

• WMAP Introduction to Cosmology

Additional Resources

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To ensure we meet the needs of the education community (you!), NASA’s UoL is committed to performing regular evaluations, to determine the effectiveness of Professional Learning

opportunities like the Science Briefings.

If you prefer not to participate in the evaluation process, you can opt out by contacting Kay Ferrari <kay.a.ferrari@jpl.nasa.gov>.

This product is based upon work supported by NASA under award number NNX16AC65A to the Space Telescope Science Institute, working in partnership with Caltech/IPAC, Jet Propulsion Laboratory, Smithsonian Astrophysical Observatory,

and Sonoma State University.

Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Aeronautics and Space Administration.

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