Mission Critical Risk-Taking:
The Hubble Deep Field
Robert Williams
Space Telescope Inst/Johns Hopkins U.
GlobForeA)SM1	
  
Kapteyn	
  1922	
  
Hubble	
  1929	
  
Kepler	
  1596	
  
Concepts of the Universe
Digges	
  1576	
  
Kravtsov & Wechsler 2010, U. Chicago
.	
  	
  	
  	
  .	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  	
  .	
  
Springel 2013 Max-Planck-Institut
HSTLaunch	
  
April	
  1990	
  
HSTSchema8c	
  
Mirror:	
  2.4m	
  diameter	
  
Mass:	
  	
  11,000	
  	
  Kg	
  
Length:	
  	
  13	
  meters	
  
Developm...
HST	
  over	
  Earth	
  
R136Blurred	
  
CartoonFirstPics	
  
CartoonFirstPics	
  
Cartoon2	
  
OTA	
  Components	
  
WFPC2Tank	
  
GlobForeA)SM1	
  
What the Longest Exposures from the
Hubble Space Telescope Will Reveal
JOHN N. BAHCALL, PURAGRA GUHATHAiKURTA,DONALD P. SC...
3C324
Distance=8 Billion light yrs
Nearby Galaxies
Nearby Galaxies
(Present epoch)
Distant Galaxies
(8 Byr ago)
HDF Spiral Galaxy NGC 3370
HDF
Palomar Hubble Telescope
Hubble Deep Field
?
Palomar Hubble Telescope
Hubble Deep Field
10″
Hubble Deep Field − North
HST • WFPC2
December 1995
HDF
10″
Hubble Deep Field − North
HST • WFPC2
December 1995
from	
  
Hubble	
  Deep	
  Field	
  
WFPC2Dark	
  
HUDF	
  
Black Hole
Stars Orbiting Center of the Milky Way Galaxy
UniverseHistory	
  
HDF
10″
Hubble Deep Field − North
HST • WFPC2
December 1995
History	
  of	
  Universe	
  
History	
  of	
  the	
  Universe	
  
StoreyonArm	
  
HDF
Mission Critical Risk Taking: The Hubble Deep Field by Robert Williams
Mission Critical Risk Taking: The Hubble Deep Field by Robert Williams
Mission Critical Risk Taking: The Hubble Deep Field by Robert Williams
Mission Critical Risk Taking: The Hubble Deep Field by Robert Williams
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Mission Critical Risk Taking: The Hubble Deep Field by Robert Williams

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MivaCon 2014: Mission Critical Risk Taking: The Hubble Deep Field

Presented by Robert Williams, Space Telescope Inst., Johns Hopkins University

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Mission Critical Risk Taking: The Hubble Deep Field by Robert Williams

  1. 1. Mission Critical Risk-Taking: The Hubble Deep Field Robert Williams Space Telescope Inst/Johns Hopkins U.
  2. 2. GlobForeA)SM1   Kapteyn  1922   Hubble  1929   Kepler  1596   Concepts of the Universe Digges  1576  
  3. 3. Kravtsov & Wechsler 2010, U. Chicago
  4. 4. .        .                          .   Springel 2013 Max-Planck-Institut
  5. 5. HSTLaunch   April  1990  
  6. 6. HSTSchema8c   Mirror:  2.4m  diameter   Mass:    11,000    Kg   Length:    13  meters   Development  Cost:    $2.5    billion   Opera8ons  24  yrs:    $5.5  billion  
  7. 7. HST  over  Earth  
  8. 8. R136Blurred  
  9. 9. CartoonFirstPics  
  10. 10. CartoonFirstPics  
  11. 11. Cartoon2  
  12. 12. OTA  Components  
  13. 13. WFPC2Tank  
  14. 14. GlobForeA)SM1  
  15. 15. What the Longest Exposures from the Hubble Space Telescope Will Reveal JOHN N. BAHCALL, PURAGRA GUHATHAiKURTA,DONALD P. SCHNEIDER Detailed simulations are presented of the longest expo- sures on representative fields that will be obtained with the Hubble Space Telescope, as well as predictions for the numbers and types of objects that will be recorded with exposures of different durations. The Hubble Space Tele- scope will reveal the shapes, sizes, and content of faint, distant galaxies and could discover a new population of Galactic stars. T HE HUBBLESPACETELESCOPE(HST) IS SCHEDULEDTO be launchedsoon andthefirstscientificobservationsshould be availablewithin severalmonths. Many authorshave discussedthe qualitativeadvancesthatmaybe anticipatedwith an orbitingspacetelescopeinsuchdiverseareasasastrometry,interstel- larmatter,stellarevolution,galacticstructureandevolution,quasar research,andcosmology(1,2). Formostobservations,theHSTwill be pointedat individualobjectsor fieldsof specialinterest.We discussthe specificset of observationsin whichthe telescopewill takepicturesof randomfields(devoidof objectsknowna priorito beof specialinterest)inorderto determinethestatisticalcharacteris- ticsof faintgalaxiesandstars. In this articlewe presentquantitativepredictionsof what the HST imagesof these representativefieldswill show basedupon whatwe knowfromground-basedtelescopes.The comparisonof the HST observationswith these predictionswill constitutean objectivemeasureof what HST discoversaboutthe propertiesof faintgalaxiesand stars.Our workinghypothesis,which will be testedbyHSTobservations,isthateverythingin theHST universe haspreviouslybeenrevealedby ground-basedobservations.Using V = 19.5 (near-infraredmagnitude I - 18.5); there are approxi- mately0.1 stars(or galaxies) arcmin-2 mag- I at this magnitude. By V = 22.5, the galaxies outnumber the stars by a factor of 10, and there are about 2.5 galaxies arc min-2 mag'l. At V = 25, the expected number of stars (-0.35 arc min-2 mag-1) is only 1% of the number of galaxies. The limiting flux level reached by long exposures on stars or faint, distant galaxies scales approximately proportional to the inverse square root of the observing time. We do not expect HST to reveal a new population of galaxies. Ground-basedobservations can detect galaxiesto avisualmagnitude limit of about V = 27 (3). This is also the approximate detection limit for relativelycompact objects (radius -0".2) with HST in the longest plannedexposures by guaranteedtime observers(GTOs) (4, 5). For a given luminosity, the more compact the object the easierit is to detect. To escape detection from the ground but still be observed with HST, the faintest galaxies (V > 27) must have angular radii of less than -0".2; this seems an unlikely possibility (see our discussion below of Fig. 4). In agreementwith previous authors,our analysissuggests that the major contribution of HST for galaxy researchwill be in revealing the shapes, sizes, and content of previously unresolved galaxies. Table1. Thenumberdensityof faintgalaxiesandstars.Thecalculatedtotal numberofobjectspersquarearcminuteathighGalacticlatitudeswithvisual magnitudes,V, and near-infraredmagnitudes,I, less than the specified brightness,m.Alsoshownarethecalculatednumberof starspersquarearc minute. For specificity,the luminosityfunctionsof faint spheroidand disk starsare assumedconstantbetweenMv = 12 and Mv = 16.5 No browndwarfsareincluded.The V galaxycountsareassumedto followa powerlawbeyondV = 26, andtheI countsareVmagnitude-limitedwith Vmax= 28 and30 for galaxiesandstars,respectively.The numbersgiven herereferto the inputdatato thesimulationsandnot to thenumbersthat wouldbe detected,whichdependuponexposuretime,detectorefficiency, Bahcall  et  al.  
  16. 16. 3C324 Distance=8 Billion light yrs
  17. 17. Nearby Galaxies Nearby Galaxies (Present epoch) Distant Galaxies (8 Byr ago)
  18. 18. HDF Spiral Galaxy NGC 3370
  19. 19. HDF
  20. 20. Palomar Hubble Telescope Hubble Deep Field ?
  21. 21. Palomar Hubble Telescope Hubble Deep Field 10″ Hubble Deep Field − North HST • WFPC2 December 1995
  22. 22. HDF 10″ Hubble Deep Field − North HST • WFPC2 December 1995
  23. 23. from   Hubble  Deep  Field  
  24. 24. WFPC2Dark  
  25. 25. HUDF   Black Hole Stars Orbiting Center of the Milky Way Galaxy
  26. 26. UniverseHistory  
  27. 27. HDF 10″ Hubble Deep Field − North HST • WFPC2 December 1995
  28. 28. History  of  Universe   History  of  the  Universe  
  29. 29. StoreyonArm  
  30. 30. HDF

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