Jennifer Lotz

Hubble Science Briefing

Jan. 16, 2014

Exploring the Depths of the UniverseExploring the Depths of the Universe

Hubble is now observing galaxies97% of the way back to the Big Bang,

during the first 500 million years

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Challenge: Can we peer deeper into the Universe than the Hubble Ultra Deep Field before the launch of the James Webb Space Telescope?

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Extragalactic Astronomy 101

1.the speed of light is finite ⇒ distance = look-back time

2.the universe is expanding ⇒ distance = velocity

3.objects moving away from us look redder ⇒ redshift = distance = look-back time

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1. distance = time

8 minutes

3 million years

13 billion years

13.7 billion years

the Sun

Andromeda

distant galaxy

echo of the Big Bang

Earth

We see distant objects as they were in the past because their light takes a long time to reach

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2. distance = velocity• the universe is expanding –

objects farther away are moving away faster

Hubble 1929Distance from our galaxy Velo

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3. velocity = redshiftredshift = distance = time

N. Wright / www.astro.ucla.edu

velocityThe light from objects moving away from us

is shifted redward.

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Galaxy redshifts are primarily due toexpansion of space, not Doppler shift

Expanding universestretches light

to longer wavelengths

ESO animation: http://www.eso.org/public/videos/redshiftv/

Redshift z =stretch factor

minus one

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(4. Astronomer’s unit of brightness)

Astronomers measure brightness in “magnitudes”

Larger magnitudes are fainter(backwards!)

Magnitude = -2.5 log10(brightness)

Faintest star the human eye can see is 6th magnitude

Hubble Ultra Deep Field reaches30th magnitude= a factor of 4 billion times fainterthan what we can see with naked eye

Frontier Fields reaches ~10x fainter than Ultra Deep Field= 40 billion times fainter than human eye can see.

Fain

ter

9Figure from http://sci.esa.int/education/35616-stellar-distances/

visible light

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when the universe was young..

NASA/WMAP Science team

blue = 0.0 Kgreen = 2.7 Kred = 4.0 K380,000 years after the Big Bang

microwaves

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When the universe was young...

blue = 2.7249 Kgreen = 2.7250 Kred = 2.7251 K380,000 years after the Big Bang

NASA/WMAP Science team 12

from the Big Bang to the Milky Way

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The Hubble Deep Field - 1995

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The Hubble Deep Field South- 19981998

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The Hubble Ultra Deep Field -2004The Hubble Ultra Deep Field -2004

new camera on Hubble = new deep fieldnew camera on Hubble = new deep field 16

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• detection of faint galaxies at look-back times < 1 billion years after the Big Bang “cosmic star-formation history” peaked ~ 10 billion years ago

• Galaxies grew in size and mass over this time, and changed their shapes from irregular to smooth

• Most distant supernovae used to measure distance, confirm accelerating universe

• Accreting supermassive black holes are found in galaxies at look-back times as early as 10-12 billion years ago.

Science Highlights from Deep Fields

Hydrogen atom excitation levels

How far away are galaxies?

Hydrogen atoms absorbs ultraviolet light from distant galaxies; this “Lyman break” is used to

estimate their redshift.

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The Hubble Ultra Deep Field -2009/2012

new camera on Hubble = new deep fieldnew camera on Hubble = new deep field19

deep infrared images needed to detect the highest redshift galaxies

The Hubble Ultra Deep Field -2009/2012

Cosm

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Redshift/time since Big Bang

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NASA/HST the Ultra Deep Field

most distant galaxy candidate

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Challenge: Can we peer deeper into the Universe than the Hubble Ultra Deep Field before the launch of the James Webb Space Telescope?

posed to the Hubble Deep Fields Initiative science working group to develop an ambitious new “community” deep fields program

HUDF ACS (optical) = 416 orbitsACS (optical) = 416 orbits

WFC3 (IR) = 163 orbitsWFC3 (IR) = 163 orbits

=579 orbits of HST

Gravitational lensing in action

23Credit: Ann Feild (STScI)

Gravitational Lensing

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Wine Glass Lensing

Phil Marshall

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Challenge: Can we peer deeper into the Universe than the Hubble Ultra Deep Field before the launch of the James Webb Space Telescope?

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Answer: Use Einstein’s theory of general relativity - “gravitational lensing ” - to go intrinsically deeper than the Ultra Deep Field.

The Frontier Fields are being observed by NASA’s Great Observatories - Hubble, Spitzer, and Chandra - over the next 3 years.

Gravitational lensing magnifies and stretches light from distant galaxies behind massive clusters, making them appear brighter and larger. Six very massive clusters of galaxies chosen as the best “zoom lenses”, with input from community.

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Frontier Fields will also observe 6 fields in parallel with the clusters, the second deepest observations of ‘blank’ fields ever obtained.

Simultaneous images are taken with Hubble’s infrared camera WFC3/IR and the optical camera ACS; cameras will swap positions ~6 months later. 29

Deep observations of the Frontier Fields will:

• probe galaxies 10-20x intrinsically fainter than any seen before, particularly those in the first billion years of the Universe

• study the early formation histories of galaxies intrinsically faint enough to be the early progenitors of the Milky Way

• study internal properties of highly-magnified galaxies at high spatial resolutions

• provide a statistical picture of galaxy formation at early times

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Deep observations of the Frontier Fields will:

+ map out dark matter, substructure in clusters

+ use 100s of multiple images as probe of distance, DE

+ search for (lensed) SN, transients in distant universe

+ deep and high-spatial resolution studies of z~1-4 galaxies, (UV escape fraction, sub-kpc structures and star-formation)

+ search for trans-Neptunian objects in solar system

+ give parallaxes of Milky Way stars

+ ???

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Spitzer Frontier Fields

Infrared Spitzer Space Telescope will look at Frontier Fields in 2 filters redder than Hubble can see to depths of ~26.5 magnitude Spitzer crucial for confirming the distant galaxies, measuring their total stellar masses

http://irsa.ipac.caltech.edu/data/SPITZER/Frontier/

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Chandra Frontier Fields

X-ray detect hot cluster gas cluster massand background accreting black holes

archival Chandra data available for all of Frontier Fields;Chandra FOV encompasses both cluster + parallel fields

new observations began this fall

MACS0717.5+3745C. Jones-Forman

MACS0416.1-2403S. Murray

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HST Frontier Fields: Clusters

Avoid dusty, bright regions of sky; visible from south (ALMA) and north (Mauna Kea)

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HST Frontier Fields

Abell 2744 MACSJ0416.1-2403 MACSJ0717.5+3745

MACSJ1149.5+2223. Abell370 Abell S1063

Hubble will observe 2 cluster per year, over 3 years140 orbits per cluster

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Cluster

Parallel ‘Blank’ Field

Abell 2744 - HST Epoch 1 completed November 2013

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Parallel ‘Blank’ Field

Cluster

Abell 2744 - HST Epoch 1 completed November 2013

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Abell 2744Parallel ‘Blank’

Field

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Abell 2744Cluster

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Abell 2744Cluster

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Abell 2744Cluster

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Abell 2744Cluster

a model of the cluster’s ‘optics’ gives us the magnification powermodel credit: J. Richard, CATS team 42

background galaxies are magnified by factors up to ~10-20, providing the deepest yet view of the universe

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background galaxies are magnified by factors up to ~10-20, providing the deepest yet view of the universe

lensed galaxies

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Abell 2744 + parallels are very very deep

Optical ACS images (blue, green, yellow) reach ~29th magnitude (dashed line)

Infrared WFC3/IR images (orange, pink, red, dark-red) >~28.7 magnitude(observed magnitudes, not intrinsic magnitudes)

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Fainter Fainter

Nu

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Nu

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Take observed fluxes x lensing magnifications (average ~1.8x, max ~80x)

⇒ intrinsically faintest Frontier Fields galaxies ~2.5 magnitudes (10x) fainter than Ultra Deep Field (blue dashed line)

Deepest view yet into the distant universe:

HUDF12 HUDF12

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Intrinsically Fainter Observed Fainter

Nu

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• The Frontier Fields is combining the power of natureThe Frontier Fields is combining the power of nature ’’s telescopes - massive s telescopes - massive clusters of galaxies - with HST to provide the intrinsically deepest view of the clusters of galaxies - with HST to provide the intrinsically deepest view of the universe yet. Parallel imaging is providing the second deepest observations of universe yet. Parallel imaging is providing the second deepest observations of ‘‘blank fieldsblank fields’’, and improve our statistical understanding of most distant and , and improve our statistical understanding of most distant and faint galaxies.faint galaxies.

• NASANASA’’s Great Observatories -- Hubble, Spitzer, and Chandra - will observe s Great Observatories -- Hubble, Spitzer, and Chandra - will observe the Frontier Field clusters and parallel fields over the next 3 years. the Frontier Field clusters and parallel fields over the next 3 years.

• The first set of Hubble observations of Abell 2744 are complete, and images The first set of Hubble observations of Abell 2744 are complete, and images have been publicly released. These reveal thousands of distant galaxies, many have been publicly released. These reveal thousands of distant galaxies, many at intrinsic luminosities ~10 times fainter than ever seen before. at intrinsic luminosities ~10 times fainter than ever seen before.

http://www.stsci.edu/hst/campaigns/frontier-fieldshttp://www.stsci.edu/hst/campaigns/frontier-fieldshttp://frontierfields.wordpress.com/http://frontierfields.wordpress.com/

https://www.facebook.com/FrontierFields https://www.facebook.com/FrontierFields

Exploring the Depths of the Universe

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Jennifer Lotz, Matt Mountain,

& the Frontier Fields TeamSpace Telescope Science Institute,Spitzer Science Center

www.stsci.edu/hst/campaigns/frontier-fields

contact: lotz@stsci.edu

Exploring the Depths of the Universe

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