Science Briefing 10/23/2019

Hubble Constant Discrepancies – Dr. Wendy Freedman (Univ. of Chicago) Dr. Charles Lawrence (JPL, Caltech) Implications for Dr. Adam Riess (JHU, STScI)

Our Expanding Universe Facilitator: Dr. Chris Britt (STScI) 1 Outline of this Science Briefing

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

2 + NASA's Universe of Learning Science Briefing

Wendy Freedman

Tension in the Hubble Constant

October 23, 2019

3 Lemaitre Hubble Robertson History

Oort Baade *** Hubble Key Project

4 + Hubble’s Sister Satellite: The Spitzer Space Telescope

Image credit: NASA/JPL-Caltech 5 The Current Tension in H0 The Current Tension in Ho The Current Tension in Ho Distance Ladder CMB

Updated from WLF et al., 2017 6 W. Freedman The Current Tension in H0 The Current Tension in Ho The Current Tension in Ho Distance Ladder CMB

Updated from WLF et al., 2017 7 W. Freedman The Current Tension in H0 The Current Tension in Ho The Current Tension in Ho Distance Ladder CMB

Updated from WLF et al., 2017 8 W. Freedman The Current Tension in H0 The Current Tension in Ho The Current Tension in Ho Distance Ladder CMB

Updated from WLF et al., 2017 9 W. Freedman The Current Tension in H0 The Current Tension in Ho The Current Tension in Ho Distance Ladder CMB

4.4 σ

Updated from WLF et al., 2017 10 W. Freedman + M101 NGC 1448 NGC 1365

Credits: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey 11 M101 NGC 1448 NGC 1365 + M101

Credits: NASA, ESA, W. Freedman (University of Chicago), ESO, and the Digitized Sky Survey 12 + A New Determination of the Hubble Constant

Distant Supernovae DistantNearby Supernovae Cepheids and Red Giants

Red Giants Distance 120 CSP SNe Ia Distance 24 calibrators

Velocity

Velocity (redshift)

13 Show TRGB separately + Ho Values With Time

P18?

WLF et al. (2019, ApJ) 14 Recent published H0 Values

15 +

 Statistical errors are well defined

 Systematics are the challenge Systematic Errors  Independent groups are now working on this issue from many different angles

 Resolution of this issue should be forthcoming in next several years

16 +  Excellent fit of the standard model ( ”Lambda Cold Dark Matter – ΛCDM) to current CMB microwave background data

 Near-term future measurements promise to rule --in or out – current proposals for new physics

17 +

Theorists are working Theory hard to try and come up with theoretical models that can explain the early and late universe measurements

18 c8c4 c802- 4b76- 49da- b8 0a- 0fb8 d02c62b7 2,095×1,24 2 pixels 10/15/2019, 17*58

H0 from the CMB

C. R. Lawrence, JPL 23 October 2019 NASA Universe of Learning Science Briefing 19

https://www.cosmos.esa.int/documents/387566/4 25793/2015_SMICA_CMB/c8c4 c802- 4b76- 4 9da- b80a- 0fb8d02c62b7?t=14 23083319437 Page 1 of 1 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.

c8c4c8 02- 4 b76- 4 9da- b80a- 0fb8d02c62b7 2,095×1,242 pixels 10/15/2019, 17*58

https://www.cosmos.esa.int/documents/387566/425793/2015_SMICA_CMB/c8 c4c802- 4 b76- 49da- b80a- 0fb8d02c62b7?t=142308 33194 37 Page 1 of 1 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.

21 c8c4c8 02- 4 b76- 4 9da- b80a- 0fb8d02Superpositionc62b7 2,095×1,242 pixels of Sound Waves 10/15/2019, 17*58

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

https://www.cosmos.esa.int/documents/387566/425793/2015_SMICA_CMB/c8 c4c802- 4 b76- 49da- b80a- 0fb8d02c62b7?t=142308 33194 37 Page 1 of 1

22 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 Planck 2018 results. I. • 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

23 From Matter Density to H0

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. Distance sound travels in 370,000 years. Depends on the density of normal matter, which Planck determines from the CMB to better than 1%.

Angle subtended by that distance, which Planck determines from the CMB to 0.03% !

24 We get H0 = 67.4 ± 0.5 km/s/Mpc

Planck 2018 results. VI.

25 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.

26 Johns Hopkins University Space Telescope Science Institute

The Expansion of the Universe, Faster Than We Thought

Review: Verde, Treu, Riess 2019, NatAs,3,891 27 SH0ES Team: Riess+2019, ApJ, 876, 85 The Standard Model of Cosmology Emerges: Early 2000’s

Big Bang Afterglow Standard Candles supernovae (supernovae) spots from Big Bang

Atoms Dark Energy (stars,etc), 70% 5% Early Late Universe Universe side side

Big Now Bang

28 SH0ES Project: Improve calibration of H0 w/ Distance Ladder (2005)

Redshifts 3 Supernova Ia Hubble Flow: Distant Galaxies D~a few Billion Lyrs

2 Supernova Ia Cepheids (pulsating stars) Cross-calibrate: In nearby Galaxies D~50-100 Million Lyrs

Geometry 1 (5 ways) Cepheids (pulsating stars) Anchors: Milky Way or just Beyond 29 D~thousands of Lyrs Era of PrecisionBetter Cosmology, Measurements 2000-present, Improving Measurements

Improved Resolution Hubble Space Telescope

80 (Riess et al. 2019) )

of Big Bang afterglow 1 73.5 - ± 1.4

60 MPC

1 Km/s/Mpc -

40 (KM S

HUBBLE HUBBLE CONSTANT 1970 1980 1990 2000

Factor of 5 improvement present expansion rate (Hubble constant) using Hubble Space Telescope from 10% to Same model, refined composition 2% uncertainty 30 Late Universe H (KITP 2019) Review by Verde, Treu, Riess (2019) 0 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

31 *includes 7th lens from Shajib+2019 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

Miras No No lens SN Cepheids TRGB (Lower )

E A (Lower

R 

L ) Y

LATE UNIVERSE (Methods) 33 The Expansion Rate Conundrum, Problem or Opportunity?

Standard Big Bang Candles Afterglow

Early Universe Late side Universe side How old Big is the Bang universe?

What are we 34 missing? State of the Universe-half full or half empty?

The Standard Model of Cosmology, ΛCDM Tensions in the Model! Cosmological “Rashomon”

? Planets Planets+ 0.05% Stars+Gas 25%

Dark Energy ? 70% Stars 0.5% Gas 4%

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

2018: NASA moves to Phase B development for WFIRST 2012: NRO gives NASA 2, 2.4m space telescopes… 2011: ESA selects Dark Energy as next mission, EUCLID 2010: 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

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 Telescopes 36 WHY STUDY THE DARK UNIVERSE?

• 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…

37 Early Late

38 Additional Resources

• 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

39 Additional Resources

• 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:

40 Additional Resources

• WMAP “Build a Universe”

• Planck mission informal education resources

• Image and video resources for WMAP

• WMAP Science Concept animations

41 Additional Resources

• Cosmology articles on Hubblesite

• WMAP Introduction to Cosmology

42 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 .

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.