20 Mars 2006 Visions en Astronomie Infrarouge
INSTRUMENTAL PROSPECTS IN INFRARED AND SUBMILLIMETER ASTRONOMY
Jean-Loup Puget Institut d'Astrophysique Spatiale, Université Paris Sud,
Orsay
20 Mars 2006 Visions en Astronomie Infrarouge
Specificities of thermal infrared astronomy
• the earth atmosphere is opaque from 13 µm to 350 µm (and still mostly opaque up 800 µm)
• thermal emission of the atmosphere and of the telescope is a severe limitation to sensitivity increasing very steeply beyond 2 µm
• in the range 10 µm to 1mm the diffraction limit is from 20 to 2000 times what it is in the V band: CONFUSION limits the sensitivity
• detector array technology progress have been slower than in the optical and near infrared (although major progress were made on individual detectors and related technology like cryogenic systems)
20 Mars 2006 Visions en Astronomie Infrarouge
how to overcome these limitations• observing from space allow your telescope:
– to be above the atmosphere– to be cooled
• uses large telescopes and interferometers• near and thermal IR adaptive optics and
interferometry• on the long wavelengths side
– in atmospheric windows– in very high altitude sites (JCMT, CSO, IRAM,
ALMA)
• the far infrared remains the most difficult; space interferomers still require a lot of developments and will not be available before a long time
20 Mars 2006 Visions en Astronomie Infrarouge(D. Scott)
Cosmic background from radio to gamma rays
CMB
CIB
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
The HDF seen by ISO (7 and 15 m)
ISOCAM team
Orange: 15 mGreen: 7 m
20 Mars 2006 Visions en Astronomie Infrarouge
Fast progress in mid IR detectors and cryogenic telescopes: SPITZER
• the Si-As BIB arrays used in MIPS allow to get– deep surveys comparable to optical ones– spectra of galaxies at redshifts beyond 3 with an 85
cm telescope !
• very efficient He cryostat in space have been built through very efficient passive cooling
• large telescopes (2 to 3.5 m) for Herschel-Planck can be cooled down below 50 K also with passive cooling
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
Typical galaxy spectrum
20 Mars 2006 Visions en Astronomie Infrarouge
Source Counts
Lagache, Dole, Puget, 2003, MNRAS
20 Mars 2006 Visions en Astronomie Infrarouge
z < 0.3
z < 2
z < 1.3
z < 1
z < 0.8
Predictions for Redshifts
Lagache, Dole, Puget et al, 2004, ApJS, 154
For S24 < 0.2 mJy: ~30% of z > 2 galaxies
bimodal contribution:
• 0.3 < z < 1 (11 to 13 µm features) peaks at 0.5 mJy
•1.6 < z < 2.5 (6 to 9 µm features) peaks at 0.2 mJy
•min contribution 1.1 < z < 1.6
20 Mars 2006 Visions en Astronomie Infrarouge
PAH at z~2
Normalized Redshift Distribution in GOODS CDFS :
-Ks sample of ~3000 sources (black)
-MIPS 24um sample (red), identified at 94% in Ks: ~730 sources:
-36% spectroscopic-21% COMBO-17-43% photo-z
-~30% of Spitzer sources are at z>1.5
8.6 m PAH Redshiftedat z~2 and Observed at
24 m !
K. Caputi et al., 2005b, submitted
20 Mars 2006 Visions en Astronomie Infrarouge Lutz et al, 2005, ApJ
PAHs at z~2.8
-2 Submm Galaxies at z~2.8 observed w/ IRS -~2hrs of integration-6.2 & 7.7 (& 8.6) PAHs-Luminosities: 1.3 to 2 1013Lo-SFR>2000Mo/yr
6.2@23
7.7@29
M82+linear AGN continuum
8.6@33
20 Mars 2006 Visions en Astronomie Infrarouge
ISO 170 m surveys
The FIRBACK survey
20 Mars 2006 Visions en Astronomie Infrarouge
Confusion
• two types: if you detect sources S>Smin • keep the probability to have not separable sources
directly linked to N(S>Smin)
• keep good signal to noise in you beam due to fluctuations of the weaker sources
• the far infrared and submillimeter is a special case: the second criteria is often coming from sources much weaker than Smin
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
•Deep cosmological surveys reveal 8 104 in K band (K<21.5)
•MIPS-24µm reveal about 2 104 galaxies per sq deg
•10 per Herschel beam at 550 µm
•250 gal per PLANCK beam !
Stacking 24 µm sources in long wavelengths maps
•possible if you have excellent/stable pointing and effective PSF
•limited by number of sources and clustering of sources (cannot do stacking when your angular resolution gets smaller than the correlation scale of the source population you study)
20 Mars 2006 Visions en Astronomie Infrarouge
Stacking Analysis 160Not physicallyrelevant but illustrative:
80<S24<83Jy
330 sourcesCDFS
[z>1.5 ?]
Dole, Lagache, Puget, 2005, astro-ph/0503017
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
beat the confusion: future steps in the stacking game
• if you can get photometric redshifts for your mid infrared sources such that– galaxies in a redshift and mid IR flux band (typically dz/z~10-
20%) have a long wavelength distribution symetrical with respect to the mean you get from stacking
– a large enough number of sources per long wavelength beam such that statistical fluctuations are getting small enough
• you can then remove these galaxies from the long wavelength maps and be left with a CIB containing only the structures associated with the redshift >2.5
• for example in a Planck map at 550 µm with 250 24 µm galaxies per beam, the error in the removal is the dispersion of the colors divided by about 15
20 Mars 2006 Visions en Astronomie Infrarouge
Instrumentation: other coming steps • at millimeter and submillimeter wavelengths
detectors close to quantum limits are being built – for Herschel
– Planck
• arrays in the far infrared are still being developped– Si detectors are very successful up to 35 µm
– Ge photoconductors have met many problems
– bolometer arrays will fly on Herschel-PACS
– arrays of TES (transition edge supra-conductor detectors) multiplexed, planar antenna detection
20 Mars 2006 Visions en Astronomie Infrarouge
Polarization sensitive bolometersAndrew Lange, Jamie Bock,Caltech-JPL
20 Mars 2006 Visions en Astronomie Infrarouge
Performances
JPL data 143 217 353 545 857 P100 P143 P217 P353
# in focal plane
4 4 4 4 4 8 8 8 8
req ms 6,3 4,4 4,4 4,4 4,4 8,4 6,3 4,4 4,4
average ms 5,2 2,5 2,3 1,2 1,9 10,3 4,5 3,2 4,2
Avg dark NEP
aW/rt Hz
11,3 13,6 11,4 29,8 30,4 9,1 10,3 14,0 12,6
NEP/BLIP 0,81 0,80 0,54 0,48 0,21 0,99 1,03 1,27 0,84
NET goal K rt s 60 92 280 13,4 8,7 102 83 134 404
Avg NET K rt s 45 70 228 8,4 5,3 82 68 111 470
(min,max) 43 50 67 751
95
258
8,0 9,4 5,0 5,8 6910
062 76 99
123
402
568
UWC data
xpol resp. 3,52% 5,96% 2,21% 5,48%
(min,max) 1,9%
5,2%
3,6%
8,9%
2,5%
3,4%
4,2%
7,0%
optical eff. 35% 32% 26% 29% 19% 32% 40% 34% 23%
(min,max) 35
%36
%31
%33%
24%
28%
27%
30%
16%
21%
25%
37%
34%
44%
31%
36%
21%
24%
Planck bolometers performances:
dark NEP below the photon noise at mm wavelengths
20 Mars 2006 Visions en Astronomie Infrarouge
Stabilisation PID2 N - thermometer PID2 N
8 nK Hz-1/2
(+0.014)
30
space qualified dilution cooler (Alain Benoit CRTBT)
20 Mars 2006 Visions en Astronomie Infrarouge
integrating sphere
CS2
CS1
mirror
polariser + crosstalk sourceson rocker
HFI CQM
20 Mars 2006 Visions en Astronomie Infrarouge
CMB spectra: temperature, E and B polarization3 observables : T, E,
B
B polarization power spectrum is
5 orders of magnitude weaker
than T for tensor/scalar
=0.1 !
E > 0
E < 0
B > 0B < 0
WMAP
PLANCK
dedicated polarization mission
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
• Observatories– ISOCAM 15 µm 6 arc sec (32*32 array)– ISOPHOT 160 µm 90 arc sec (4 individual pixels)– SPITZER-MIPS
• 24 µm 5.6 arcsec (128*128 array)• 160 µm (2*20 array)
– JCMT-SCUBA 850 µm – IRAM PdB – HERSCHEL 550 µm
• All sky Surveys– IRAS 1.5 arcmin/0.5 Jy at 100 µm, 30 arcsec/0.5Jy at 12 µm – COBE 40 arc minutes – ASTRO-F – PLANCK 550 µm, 5 arc minutes
20 Mars 2006 Visions en Astronomie Infrarouge
redshift ranges contributing to the CIB
Wavelength (µm) z 50% z 20% - z 80%
15 0.8 0.5 – 1.5
70 0.8 0.5 – 1.6
24 1.4 0.6 – 2.2
160 1.35 0.6 – 2.3
350 2 0.9 – 3
850 2.8 1.8 – 4
2000 3.5 2 – 5.5
20 Mars 2006 Visions en Astronomie Infrarouge
20 Mars 2006 Visions en Astronomie Infrarouge
CIB SED
Lagache, Dole, Puget, 2003, MNRASlong wavelengths emissivity 1.5 to 2
20 Mars 2006 Visions en Astronomie Infrarouge
PAHs at z~1.8 to 2.6
Yan et al, 2005, ApJ in press
-8 24 m galaxies targetted w/ IRS (52 total)
-6 MIR features detections: 1.8 < z < 2.6
-6.2 & 7.7, 8.6, 11.3 PAHs (+Si abs)
-Luminosities: 0.6 to 4 1013Lo
20 Mars 2006 Visions en Astronomie Infrarouge
Cosmic Infrared Background• 24 m
– Down to 60 Jy– 75% resolved– By integration of the source counts, CIB@24 is
2.7 +1.1-0.7 nWm-2sr-1
• 70 m– Down to 15 mJy– ~23% resolved
• 160 m– Down to 45 mJy– ~7% resolved
• References– Papovich et al., 2004– Dole et al., 2004
20 Mars 2006 Visions en Astronomie InfrarougePapovich, Dole et al, 2004, ApJS
24 m
Differential Source Counts
Dole et al, 2004a, ApJS
20 Mars 2006 Visions en Astronomie Infrarouge
Planck planned capabilities
20 Mars 2006 Visions en Astronomie Infrarouge
One year mission CMB performances
100 143 217 353 545 857
beam sizearcmi
n 9,5 7,1 5 5 5 5
n pixels 1,65E+06 2,95E+06 5,94E+06 5,94E+06 5,94E+06 5,94E+06
system sensitivity to T
K rt s 28,8 16,4 26,1 93,9 4,2 2,6
system sensitivity to Q,U
K rt s 43,8 38,1 58,9 262
avg time/pixel s 19,2 10,7 5,3 5,3 5,3 5,3
T/pixel K 6,6 5,0 11 40 273 11987
T/T/pixel 10-6 2,4 1,9 4,2 15,0 101 4423
T/T/pixel bluebook 10-6 2,5 2,2 4,8 14,7 147 6700
(Q,U)/pixel K 10,0 11,6 25,6 114
(Q,U)/T/pixel 10-6 3,7 4,3 9,4 41,9
(Q,U)/T/pixel bluebook 10-6 4 4,2 9,8 29,8
20 Mars 2006 Visions en Astronomie Infrarouge
Comparison CIB in optical/IR
• Energy in the extragalactic background : < 6 m: 2 4.2 10 -8 W m-2 sr-1
> 6 m: 4 - 5.2 10 -8 W m-2 sr-1
=> E(Far-IR) / E(opt) ~1 – 1.25• Local Universe:
– E(Far-IR) / E(opt) = 0.4 !!!• Conclusion:
– Strong increase of the IR ouput energy with z• Questions:
– stars or massive black holes as the main energy source– role of IR galaxies in the building of galaxies as we see them today– does the emerging picture fits or not in the standard model of
hierarchical structure formation
20 Mars 2006 Visions en Astronomie Infrarouge
Updated 2004 LDP Model
Lagache, Dole, Puget, et al, 2004, ApJS
7.5% 3%