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Report on work done for NIO GSMT book. Simon Morris With Cedric Lacey, Robert Content, Marc Dubbledam. Simulated NGST Image (Im 2001) 2’x2’ 10 hr exposure. High z Lyman Emitters. Ellis et al. z=5.6 lensed Lyman Alpha emitters Brighter object observed I=26, lensed by factor ~33. - PowerPoint PPT Presentation
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University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Report on work done for NIO GSMT book
Simon Morris
With Cedric Lacey,
Robert Content, Marc Dubbledam
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Simulated NGST Image
(Im 2001)
2’x2’
10 hr exposure
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
High z Lyman Emitters
Ellis et al. z=5.6 lensed Lyman Alpha emittersBrighter object observed I=26, lensed by factor ~33
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
‘Natural Seeing’ •Exposure 4x8 hours (~105 seconds), sky I=19.9• 27% sky-to-hard-disk throughput• 50% of object flux in 0.6x0.6 arcsec box• All of line flux in 2 spectral pixels (1.7 nm)• 5 Detection for 3x10-19 ergs cm-2 s-1
• Z=6 (Observed =851.2 nm) gives 1x1041 ergs s-1 luminosity
ELT MEIFU Emission Line Sensitivity Calculation
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
AO corrected and ‘diffraction limited’ • Assumption as in previous slide, except:• 50% of object flux in 0.2x0.2 arcsec box• 5 Detection for 1x10-19 ergs cm-2 s-1
• Z=6 (Observed =851.2 nm) gives 3x1040 ergs s-1 luminosity• 50% of object flux in 0.006x0.006 arcsec box (50% EE diameter for 30m Airy Pattern at 790 nm)• N.B. this also implies a different plate scale to sample this properly.• 5 Detection for 3x10-21 ergs cm-2 s-1
• Z=6 (Observed =851.2 nm) gives 1x1039 ergs s-1 luminosity
Emission Line Sensitivity Calculation
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Semi-analytic surface density prediction
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Semi-analytic continuum mag prediction
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Spatial Correlation Function in co-moving coordinates for Lyman emitters.
Assumed constant fixed escape fraction.
Single flux range
Points = Lyman emittersLines = Dark Matter
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Fluorescent Lyman Alpha Emitters• Can we detect neutral hydrogen clouds excited by the general UV background?• Gould and Weinberg 1996, ApJ, 468• Bunker, Marleau and Graham 1998, AJ, 116, 2086
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Re-Calculate above using most recent estimates for the UV background• Calculations done in mathCAD, electronic version of this (and also the sensitivity calculation) will be included in the final delivery.• Algorithm:
• Assume ‘consensus’ cosmology• Use Haardt and Madau (1996) functional form for UV background strength and shape as function of z, but with latest version for parameters (Haardt, Private Comunication, CUBA code)• Use Power law approx. to hydrogen photoionisation cross section (simplifies code, but not necessary)• Consider clouds both optically thin and optically thick to UV background as separate cases using Gould and Weinberg formalism• Calculate cloud luminosities given a characteristic size• Convert these to fluxes and surface brightnesses given the redshift• Given known number of absorbers as a function of column density and redshift, and assuming the same characteristic size, calculate volume density of clouds expected satisfying given flux and surface brightness limits.
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
0 1 2 3 4 5 6 722
20
18
16
14
logFthick Rchar zp erg cm
2 s1
logFthin Nchar Rchar zp
erg cm2 s
1
zp
0 1 2 3 4 5 6 722
21
20
19
18
17
logSBthick Rchar zp
erg cm2 s
1 arcsec2
logSBthin Nchar Rchar zp erg cm
2 s1 arcsec
2
logSBBunker zp
erg cm2 s
1 arcsec2
zp
Ly Flux
Ly SurfaceBrightness
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
0 1 2 3 4 5 6 70
10
20
30
Rchar
dA zp arcsec
zp
0 2 4 6 83
2.8
2.6
2.4
2.2
2
log Nthick zp Rchar
Mpc3
zp
Angular Size(Rchar=50 kpc)
Volume Density of optically thick absorber/emitters
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Log(SFR M/yr)
Log
(N
umbe
r M
pc-3) LBG,
80% complete?
Ly emitters, 25% complete?
What are we selecting?
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
GSMT
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
MEIFU Mechanical design for fixed Cassegrain
GSMT focus
University of Durham Astronomical Instrumentation Group
ELT Science Case, Oxford, 28.04.03
Ballpark Mass Budget(no lightweighing)
Fused Silica glass ~ 2.2 g/cm3
Single Spectrograph glass mass ~ 400 kg 1000 kg per spectrograph 24,000 kg for all spectrographs 16,000 kg for remaining structure 40,000 kg for whole instrument