Massimo Stiavelli Space Telescope Science Institute
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Transcript of Massimo Stiavelli Space Telescope Science Institute
Massimo StiavelliSpace Telescope Science Institute
The Making of the Hubble Ultra Deep Field
Hubble Science BriefingOctober 4, 2012
Bold methods and new technologyBold methods and new technology
- What happens if you point the most powerful camera at the same point in the sky for an unprecedented length of time?
The Wide Field Planetary Camera 2 (WFPC2)
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The Hubble Deep FieldThe Hubble Deep Field
- This is exactly what Bob Williams, then STScI Director, decided to do in 1994.
- The resulting image, known as the Hubble Deep Field, was the deepest picture of the Universe for many years.
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A new instrument…A new instrument…
- A new camera was installed on Hubble in March 2002: the Advanced Camera for Surveys.
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…is a new opportunity…is a new opportunity
- The new STScI Director, Steve Beckwith, decided to use the new, more powerful camera and point it for twice as long as the HDF on a fixed spot in the sky
- The Hubble Ultra The Hubble Ultra Deep Field (HUDF) Deep Field (HUDF) was bornwas born
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More than just fishingMore than just fishing- The HUDF was doing more than just
looking for the unknown- The Sloan Digital Sky Survey (SDSS) had
identified the most distant quasars known, formed about 1 Gyrs after the Big Bang
- Spectra of these objects, taken with Keck and other telescopes, were showing tantalizing clues…
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Reionization of the UniverseReionization of the Universe
- Spectra of the most distant QSOs (quasi-stellar objects) told us that there was some neutral hydrogen in their vicinity
- This is not seen for less distant QSOs
- Galaxies must ionize all hydrogen about 1 Gyrs after the Big Bang
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Could Hubble see them?Could Hubble see them?
- The question then was whether Hubble could see the galaxies responsible for reionization.
- This was the science motivation for the HUDF
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How do you create a deep field?How do you create a deep field?
- Select a carefully chosen random location in the sky
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Field Location OptionsField Location Options
UDFUDF
Hubble Ultra Deep FieldHubble Ultra Deep Field1212
Yes, mostlyYes, mostly
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What about earlier times?What about earlier times?- The galaxies found in the HUDF are the
most distant that can be found in the optical portion of the electromagnetic spectrum; for more distant objects you must search the infrared portion.
- The existing infrared camera (NICMOS) on Hubble gave some hints, but was not powerful enough to do the job.
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- Earlier than 1 Gyrs after the Big Bang, galaxies are faint and relatively rare. We need a sensitive IR instrument: the IR channel of the Wide Field Camera 3 (WFC3).
Need infrared!Need infrared!
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More galaxiesMore galaxies
- WFC3 gave us samples of galaxies all the way to about 650 Myrs after the Big Bang.
- As we go back in time, galaxies become rarer and fainter
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eXtreme Deep Field (XDF)eXtreme Deep Field (XDF)- Galaxies from 650 Myrs to 500 Myrs are
elusive, but possibly within the reach of Hubble.
- To study them one needs very long integrations, on the order of many hundreds of hours
- The XDF is the latest and deepest attempt at studying these objects.
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eXtreme Deep eXtreme Deep FieldField(XDF)(XDF)
Garth D. Illingworth Webinar September 20121818
Moon
XDF
1919Garth D. Illingworth Webinar September 2012
2020Garth D. Illingworth Webinar September 2012
2121Garth D. Illingworth Webinar September 2012
2222Garth D. Illingworth Webinar September 2012
2323Garth D. Illingworth Webinar September 2012
2424Hubble eXtreme Deep FieldHubble eXtreme Deep Field
How XDF lets How XDF lets usus see the early see the early universe universe
Galaxies earlier than 800 Myr after the Big Bang can only be seen in infrared light (“redder” than visible light)
We need We need near-infrared near-infrared
images to images to see them!see them!
observed wavelength [microns]
Galaxy Light
HUDFXDF
2525Garth D. Illingworth (Galaxy Light) Webinar September 2012
Credit: STScI
previous imageHUDF
new imageXDF
XDF reveals galaxies unseen in XDF reveals galaxies unseen in our deepest visible-light HUDF our deepest visible-light HUDF
imagesimages
2626Garth D. Illingworth Webinar September 2012
A red galaxy is not necessarily in A red galaxy is not necessarily in the very early universethe very early universe
Red galaxy colors can also be a sign for old stars, or for a lot of dust, which absorbs blue light
These two galaxies are at a distance of about half the age of the universe
This galaxy is about 13 billion light years away
2727Garth D. Illingworth Webinar September 2012
Even more distant galaxiesEven more distant galaxiesEven more distant galaxiesEven more distant galaxies
- A redshift 10 galaxy
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Why are the early times so important?Why are the early times so important?
Years: 0.3 8 16 32
For both humans and galaxies the pace of development is not uniform: more things happen early on 2929
Changing how astronomy is doneChanging how astronomy is done
- The HDF image and the source catalogs were made public.
- Astronomers started using other telescopes to study specific objects, measure redshifts, obtain radio or X-ray data.
- Most of these data were also made public.
From American Physical Society Newsletter May 1997 3030
PapersPapers- The HDF and HUDF surveys led to 1,584 research
papers, of which only 89 were published by the team.
• The vast majority (94%) of these science papers were published by other scientists
- The HDF was the first case in astronomy of highly valuable data made public, and it encouraged open cooperation.
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CDF-S* region is rich in data (HST, Spitzer, Chandra, etc)[*Chandra Deep Field South]
CDF-S* region is rich in data (HST, Spitzer, Chandra, etc)[*Chandra Deep Field South]
1999-2000 Chandra CDF-S 2002-2003 ACS GOODS2003 ACS HUDF2003 NICMOS HUDF 2004 Spitzer GOODS 2003-2007 NICMOS2005 HUDF05 2009 ERS2009-2010 HUDF092010-2011 Chandra 4Ms 2010-2012 CANDELS2012-2013 Ellis
All these data were available within 3 months.
CDF-South
~22’ x 22’3232
Garth D. Illingworth STScI May 2010 Workshop
No more lonely hearts of the cosmosNo more lonely hearts of the cosmos
- The old-style way of doing research in small research group is being replaced by participation in large groups.
- In the past astronomers tended to focus on a few specific objects Now we focus on large samples
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Non-hierarchical scienceNon-hierarchical science
- In a large collaboration working on a large sample, the difference between team members and non-team members starts to fade.
- This opens up possibilities for unaffiliated astronomers, and also for the interested public.
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Galaxy Zoo: HubbleGalaxy Zoo: Hubble
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JWSTJWST
Ultimately, in order to see more and fainter objects at these redshifts we need a telescope designed for infrared imaging:
the James Webb Space Telescope
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6.5m James Webb Space Telescope6.5m James Webb Space Telescope3838
Full-scale modelFull-scale model
The Hubble UDF (F105W, F105W, F160W)
Simulated JWST
JWST improvements over Hubble’s resolution
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JWST improvements over Hubble’s resolution
The Hubble UDF (F105W, F105W, F160W)
Simulated JWST
4103/07/2010
HST/ACSViz
HST/NICMOS J H
JWST/NIRCamViz
(simulated)
JWST/NIRCamJ H
(simulated)
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JWST-Spitzer image comparisonJWST-Spitzer image comparison
Spitzer, 1500 min. per band
(GOODS collaboration)
1’x1’ region in the HUDF – 3.5 to 5.8 m
JWST, 16 min. per band (simulated)(simulation by S. Casertano)
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Hubble & James Webb to same scaleHubble & James Webb to same scaleHubble & James Webb to same scaleHubble & James Webb to same scale
JWST is 7 tons and fits inside an Ariane V shroudThis is made possible by:
• Ultra-lightweight optics (~20 kg/m2)• Deployed, segmented primary mirror• Multi-layered, deployed sunshade• L2 Orbit allowing open design/passive cooling
Astronaut
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JWST Launch ConfigurationJWST Launch Configuration
LongFairing17m
Upper stage
H155 Core stage
P230 SolidPropellantbooster
Stowed Configuration
JWST is folded into stowed position to fit into the payload fairing of the Ariane V launch vehicle
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ConclusionsConclusions
WFC3-IR has allowed us to begin studying galaxies up to 650 million years from the Big Bang.
Progress on these objects is going to be slow because they are too faint for any existing telescope, save for major efforts like the XDF.
The James Webb Space Telescope has the sensitivity required to study these objects and even earlier ones.
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