Quasars and Galaxies at the Highest Redshifts

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Quasars and Galaxies at the Highest Redshifts

• Richard McMahon
• Institute of Astronomy
• University of Cambridge, UK

Crafoord Symposium, Stockholm, Sep 2005
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Some Background Information

• Main motivation is that objects at high redshift
  are young due to the light travel time. e.g. we
  can see objects that existed in the Universe
  before the Earth formed.
• Quasars are the most luminous members of the
  Active Galactic Nuclei (AGN) family.
• MBlt -23 AGN light exceeds energy from host
  galaxy stellar light.
• Quasars are intrinsically luminous bright beacons
  that are easier to observe that normal galaxies
  like the Milky Way. Also illuminate intervening
  material. i.e. IGM
• Energy source is accretion of matter onto a
  super-massive black hole (107 to 109 Msol )
• Rees, 1984, ARAA, 22, 471, Black Hole Models
  for Active Galactic Nuclei
• Recent observations have shown that most massive
  galaxies in the local Universe host super-massive
  black holes. The BH mass is correlated with the
  stellar bulge mass implies that the formation and
  evolution of BH and the stellar component in
  galaxies related (Magorrian et al, 1998
  Ferrarese Merrit, 2000 Gebhardt etal, 2000)
• Rees, 1989, RvMA, 2, 1, Is There a Massive Black
  Hole in Every Galaxy?
• Radiative feedback from quasars may play a major
  role in formation and evolution of galaxies.

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Look Back Time
Redshift Look back Time (Gyr) Age of Universe
0 0.0 13.5 Gyr
0.5 5.0 8.5
1.0 7.7 5.7 Gyr
3.0 11.4 2.1 Gyr
6.0 12.5 915 Myr
8.0 12.8 630 Myr
10 13.0 460Myr
30 13.4 97 Myr
100 13.45 16 Myr
1000 13.46 0.42 Myr
?matter, ??, H0 0.3, 0.7, 70
Formation of Solar System 5 Billion year ago
(5Gyr)
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Highest Redshift History
Quasars
Galaxies
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Highest Redshift History
Gunn
Quasars
Galaxies
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The Observational Challenges in surveys for
surveys for high redshift objects

• Experimentally difficult because
• Distant objects are very faint.
• Rest frame UV radiation is red-shifted to regions
  of observed sky spectrum where night-time sky is
  bright.
• Foreground objects are much more numerous so the
  experimental selection technique has to be very
  efficient.
• May be undetectable, in a reasonable amount of
  time using current technology i.e. may need to
  wait or develop the technological solution.

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Basic observational principles in optical surveys
for higher redshift quasars and galaxies

• UV drop-out due to
• Intrinsic or Intervening Neutral Hyrogen Lyman
  limit at 912Å.
• Intervening Lyman-a forest (?lt1216Å)
• Emission line searches based on
  Lyman-?(?rest1216Å) emission from ionized
  Hydrogen.

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3C273 and z3.62 comparison
Evolution of HI 3C273 spectrum from HST/FOC
z0 z3.6 QSO HIRES/Keck spectrum from M. Rauch
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z4 Model Quasar SDSS filter set
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Multi-colour Selection and discovery of zgt4
Quasars (pre-SDSS)
Only two wavebands are needed. In practice this
results in some(50) contamination by M-stars
Cambridge-APM Surveys See Storrie-Lombardi,
Irwin, McMahon and Hook, 2001. n49 zgt4
quasars 15, 000 deg2
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Lyman-? (?rest1216Å)
Quasars at z ? 5
C,N,O,Si .
Lyman-? Forest
z 4.90, Schneider, Schmidt, Gunn, 1991, AJ, 98,
1951
z 5.0, Fan with Guun, Lupton et al. 1999 (SDSS
collaboration)
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z5 quasar with SDSS filters
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z6 quasar with SDSS filter set
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SDSS Surveys for zgt5 Quasars
Fan, et al.

• Color selection of i-drop out quasars
• At zgt5.5, Lya enters z-band ? quasars have red
  i-z colour
• Technical Challenges
• Rarest objects
• One z6 quasar every 500 deg2
• Key contaminant elimination
• Major contaminants are L and T type Brown Dwarfs
  ? additional IR photometry

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zgt5.7 quasars
Fan, Narayanan, Lutpon, Strauss et al.

• Separating z6 quasars and Brown Dwarfs
• Follow-up IR photometry
• quasar z-J 1
• L to T dwarf stars
• z-J gt 2

Zgt5.7 quasar
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SDSS compilation zgt5.7 quasars
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Edited Quasar compilation (pre-SDSS)
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Quasar compilation (now with SDSS)
?
DR3QSO 50, 000 quasars
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Higher Redshift Quasar Surveys

• Need to work in Infra-Red
• Different detector technology
• Sky brightness problem
• Two relevant projects
• UK Infra Red Deep Sky Survey (UKIDSS)
• WFCAM on UKIRT
• Survey started in May 2005
• Pipeline Data processing centre(CambridgeEdinburg
  h)
• VISTA (will be an ESO telescope) (Surveys will
  start in early 2007?)

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The Night Sky Problem
Broad band sky gets brighter as you go to redder
wavelengths
Waveband Central Wavelength (Angstroms) Dark Sky Brightness Redshift Lyman-? (1216Å)
B 4400 22.1 2.6
V 5500 21.3 3.5
R 6000 20.4 3.9
I 7500 19.0 5.2
Z 8900 18.0 6.4
Y 10,300 17.0 7.5
J 12,500 16.0 9.3
H 16,500 14.0 12.6
K 22,000 13.0 16.3
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z6 quasar (SDSS filter set)
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z7 quasar (SDSS filter set)
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z8 quasar (SDSS filter set)
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z6 quasar (SDSS filter set WFCAM)
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z7 UKIDSS/VISTA Filters
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z8 UKIDSS/VISTA Filters
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z9 UKIDSS/VISTA Filters
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z10 UKIDSS/VISTA Filters
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UK Infra Red Telescope (UKIRT) Wide Field Camera
(WFCAM)

• 3.6m telescope
• Mauna Kea, Hawaii
• 4x2048x2048 Hawaii II arrays
• 0.4 arcsec pixels
• 0.21 sq. degs / exposure
• Not contiguous
• Filters
• Z,Y,J,H,K,H2-S(1),Br-g

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UKIRT Wide Field Cameraon Telescope Simulator
WFCAM cryostat
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UKIDSS overview5 elements of UKIDSS(5-7 year
duration)
Sub-Survey Bands Limit (K) Area deg2 nights
Large Area Survey LAS YJHK 18.4 4000 262
Deep Extragalactic Survey DXS JK 21.0 35 118
Ultra Deep Survey UDS JHK 23.0 0.77 296
Galactic Plane Survey GPS JHK 19.0 1800 186
Galactic Clusters Survey GCS JHK 18.7 1600 84
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UKIDSS Science goals
Cool Universe - Y brown dwarfs Obscured
Universe - Galactic plane - reddened
AGN, starbursts, EROs High-redshift Universe -
4000A break zgt1 high redshift galaxy clusters
- Quasars at zgt6.5
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Current Status of WFCAMUKIDSS

• Instrument started commissioning on-sky phase in
  Nov, 2004
• Science Verification started in April 2005
• UKIDSS Survey started in May, 2005
• Instrument taken off telecope in June, 2005
• As planned
• Survey restarted end of Aug, 2005
• Should have 100deg2 of data by end of 2005

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Visible and Infrared Survey Telescope for
Astronomy

• 4-m wide field survey telescope at European
  Southern Observatory (ESO) , Paranal near the VLT
  site.
• Initially Infra Red camera only. (i.e. an IR
  SDSS)
• 75 time for large surveys. (e.g. Southern
  SDSS)
• UK project (consortium of 18 Universities funded
  in 1999)
• Principal Investigator Jim Emerson (QMUL,
  London)
• Now part of UK ESO late joining fee.
• Will become ESO facility on completion of
  construction and commissioning in late 2006.

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The Heart of VISTA the IR focal plane

• 16 IR arrays, each 2048 x 2048 sparse filled
  mosaic
• 0.60 deg2 covered by detectors
• 0.34 arcsec/pix.
• 6 consecutive offset pointings give a
  continuous region
• 1.5deg by 1.0deg i.e. 1.5deg2
• every pixel covered by 2 pointings.

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Comparison of IR camera field sizes
Moon!
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Dome May 05
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Summer 2005
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• Design Reference Programme (epoch 2001 400
  clear nights)
• used for Project Planning
• ESO Survey Call for Proposal is being planned
• Z filter now included

Survey name            Area (deg2) Y J H Ks Clear nights (ex overheads)
(Vega, 5s) (Vega, 5s) (Vega, 5s) (Vega, 5s)

Very deep 15 23.8 22.5 22.0 55
Deep 100 22.8 21.5 21.0 57
Wide (high-gal lat) 3000 22.0 21.2 20.0 19.5 100
Galactic Plane Magellanic Clouds 1500 21.5 20.5 19.5 19.0 45
Sky Atlas 20000 20.2 18.2 150
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Highest Redshift Galaxies
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Searches for higher redshift quasars and galaxies

• UV drop-out technique survey technique due to
• Intrinsic or Intervening Lyman limit 912Å.
• Intervening Lyman-a forest (?lt1216Å)
• Emission line searches based on Lyman-? emission
  from ionized Hydrogen.

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Highest Redshift History
Quasars
Galaxies
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High Redshift Lyman-? emission lines
surveysAstrophysical principles for Success

• Partridge and Peebles, 1967, Are Young Galaxies
  visible?
• Minimum Flux limit
• Previous surveysin the early 1990s were based on
  the simple paradigm of a monolithic collapse.
• expected star formation rates of 50-500 Msol yr-1
  
• i.e. the SCUBA/FIR Population?
• Assume SFR detection limits more appropriate to a
  slowly forming disc or sub-galactic units in a
  halo
• i.e. 1-3 Msol yr-1
• 1.0-2.0 ? 10-17erg s-1 cm-2 at z4
• Minimum Volume
• search a comoving volume within which you expect
  to find the progenitors of around 10 L galaxies.
  (.i.e. Milky Way mass)
• Local density 1.40.2 ? 10-2 h50 Mpc-3 (e.g.
  Loveday etal, 1992)
• minimum is 1000 Mpc3

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Potential Narrow band filter locations
5.7 6.6 6.9
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z5.7 for Lyman-?
z6.6 for Lyman-?
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Basic experimental principle

• Basic principle is to survey regions where the
  sky sky spectrum is darkest in between the
  intense airglow.
• Gaps in the OH airglow picket fence
• Lyman-alpha redshifts of gaps in
  Optical-Silicon CCD regime
• 7400 Å z5.3
• 8120 Å z5.7 used extensively
• 9200 Å z6.6 used extensively
• 9600 Å z6.9 no results yet
• CCDs have poor QE and sky relatively bright

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Summary of known spectroscopically confirmed
zgt6.0 galaxies

• Narrow Band Surveys
• zgt6.0 n13
• from Hu et al. 2002(1), Kodeira et al. 2003(2),
  Rhoads et al 2004(1), Taniguchi et al. 2005(9)
• z(max)6.6
• Other Surveys
• 2 other zgt6 emission line selected galaxies
• Kurk et al, 2004(1) Stern etal, 2005(1)
• Ellis etal, lensed search z7 candidate (no line
  emission photo-z)
• i-drops Nagao et al, 2004(1) Stanway etal,
  2004(1)
• Quasars SDSS n5 (6.0lt zlt6.5)

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?(observed Lyman-?)9190Å ?(rest
Lyman-?)1216Å Redshift6.558
Hu, etal, 2002
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z6.597 galaxy (Taniguchi et al, PASJ, 2005)

• Survey
• Subaru 8.2m
• Suprimecam 34 x 27 0.2/pixel
• 132Å filter centred at 9196Å
• Exposure time 54,000 secs (15hrs)
• Results
• 58 candidates
• 9 spectroscpoically confirmed with z6.6

9235Ang
redshift 6.597
zAB 26.49
i-z gt1.72
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Composite spectrum of z5.7 candidate galaxies
z0.6 unresolved and 4959 line
OIII4959
OIII(5007Å)
z1.2 note resolved doublet
OII(3727Å)
z5.7 note asymmetry
n18 galaxies
Lyman-?(1216Å)
Hu, Cowie, Capak, McMahon, Hayashino, Komiyama,
2004, AJ, 127, 563
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z5.7 Lyman-?(1216Å) emitters
Observed wavelength (Angstroms)
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z1.2 OII3727 doublet emitters
Observed wavelength (Angstroms)
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The Night Sky Problem
Broad band sky gets brighter as you go to redder
wavelengths
Waveband Central Wavelength (Angstroms) Dark Sky Brightness Redshift Lyman-? (1216Å)
B 4400 22.1 2.6
V 5500 21.3 3.5
R 6000 20.4 3.9
I 7500 19.0 5.2
Z 9000 18.0 6.4
J 12,500 16.0 9.3
H 16,500 14.0 12.6
K 21,000 13.0 16.3
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Narrow band searches in the near Infrared

• OH lines contribute 95 of sky background in
  1.0-1.7?m range
• i.e. 20 times the continuum emission.
• Filters need to have widths of 10Å or 0.1 to
  avoid OH lines.
• c.f. 100Å in the optical
• NB. Narrower band means you solve a smaller
  redshift range i.e. volume so wide field is
  needed.
• Some of the technical issues
• Filter design and manufacture
• Field angle shift of central wavelength
• Out of band blocking

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Infrared OH Sky Observations Mahaira etal, 1993,
PASP
GOOD NEWS The 1.0 to 1.8 micron IR sky is very
dark between the OH lines which contain 95 of
broad band background.
THE NOT SO GOOD NEWS The narrowest gaps are
narrower than in the optical filter widths of
0.1 per cent are needed compared with 1 filters
in optical. THIS IS A TECHNICAL CHALLENGE WE
HAVE SOLVED see Ian Parrys talk
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DAZLE Dark Age Z Lyman Explorer McMahon, Parry,
Bland-Hawthorn(AAO), Horton et al
IR narrow band imager with OH discrimination at
R1000 i.e. 0.1 filter FOV 6.9 ? 6.9 arcmin 2048
Rockwell Hawaii-II 0.2/pixel Sensitivity 2.
10-18 erg cm-2 sec-1(5?), 10hrs on VLT i.e. 1
M? yr-1 at z8
Sky emission and absorption spectrum around 1.06
and 1.33 microns showing DAZLE filter pairs for
Lyman ? at z7.7, 9.9 other gaps are at 8.8, 9.2
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DAZLE Digital state

• 3D CAD drawing of DAZLE Final Design on VLT
  UT3(Melipal) Visitor Focus Nasmyth Platform.
• UT3 optical axis is 2.5m above the platform floor
• grey shading shows the DAZLE cold room(-40C)which
  is 2.5m(l) x 1.75m(w) x 3m(h).
• Blue Dewar at top contains the 2048 x 2048 pixel
  IR detector

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Dazle in Cambridge Laboratory(Aug 2005)
Refridgeration Box
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Highest Redshift History
Quasars
Galaxies
60
Quasar compilation (now with SDSS)
?
DR3QSO 50, 000 quasars
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Some Future ground based surveys for higher
redshift Galaxies and Quasars

• zgt7 galaxies
• Dark Ages Z Lyman-? Explorer (DAZLE) on the VLT
  (to start Jan 2006)
• zgt7 quasars
• UKIDSS UK Intra-Red Deep Sky Survey (started May
  2005 5 year survey project)
• UKIRT (Hawaii) WFCAM
• ESO members Public Access from late 2005)
  Worldwide 18month
• VISTA Surveys (to start early 2007)

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FINAL SLIDE