1. 45 years of developments around the CIB 1967-2012 Jean-Loup Puget Institut d’Astrophysique Spatiale CNRS, Université Paris Sud 29/10/2015 - from CIB to CIB anisotropies - early interest and predictions for the Cosmic Backgrounds - the search for the CIB -evolution of the ideas the technology the data analysis leading to the observations - what to we hope to learn today Herschel, Planck, SPT, ACT,…

2. Cosmic backgrounds: CMB, CIB, Gamma,… UV redshifted in near IR cosmic background –following the observation of the CMB (1965), work developed on the cosmic backgrounds at other frequencies –one key “astrophysical cosmology” question was “where is integrated radiation from the nucleosynthesis of the heavy elements we see today” –Partridge and Peebles 1967 “Are young galaxies visible ?” (ApJ 148,377), young galaxies 700 times more luminous than the milky way, z =10-30 Sciama and Rees 1967 (ApJ 147, 868) heavy elements detectable or not in the E.G.M mid IR line cosmic background FIR cosmic background 29/10/2015

3. Growing interest for a FIR redshifted in submm cosmic background (1/2) –F. Low The Infrared-Galaxy Phenomenon 1970 (ApJ 159, L173) –50-300 µm observations of the Galactic center and NGC1068 and M82 (2 10 12 and 6 10 11 L o ) by Franck Low and H. Aumann 1970, ( ApJ 162, L79) –in 1972 the Fundamental panel of ESRO (not yet ESA !) asked me a report on what can space observations bring to cosmology and fundamental physics and I stressed the potential measurements of the cosmic backgrounds –the driving questions were two fold: the opacity of the universe to ultra high energy particles and photons learning about the early stages of galaxy formation and the history of nucleosynthesis 29/10/2015

4. predictions from a report to ESRO (1972) windows in foregrounds 29/10/2015 Puget J.L. 1972, report to the fundamental physics panel of ESRO CMB EBL / CIB Zodi CIRES project

5. Growing interest for a FIR-submm CB (2/2) –Setti and Woltjer: Infrared Background and Universal Cosmic Rays 1971 (Nature Phys Sc 231, 57) – J.L. Puget, F.W. Stecker, J. Bredekamp : Photonuclear interactions of ultrahigh energy cosmic rays and their astrophysical consequences1976, (ApJ 205, 638), F.W. Stecker, J.L. Puget, G. Fazio Cosmic far infrared background at high galactic lattitudes 1977, (ApJ let 214, L 1) the relative contribution to FIR luminosity from galactic nuclei vs star formation remained unclear for 20 years 29/10/2015 1994 1996

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7. predictions of the anisotropies of the CIB Not only the SED of the CIB but its angular power spectrum was predicted to be a powerful tool to explore the star formation history in the universe R. Bond, B. Carr and C. Hogan 1986 (ApJ 306, 428), 1991 (MNRAS), D. Scott and M. White (A &A 346,1), Z. Haiman and L. Knox 2000 (ApJ) This is still to come ! In the 80s it was not clear what was the best strategy to search the CIB for two reasons: -what fraction of the UV stellar energy was absorbed by dust and re-emitted in the FIR ? (near IR or FIR CIB ?) -COBE-DIRBE was aiming at both -in the e.m. spectrum where are the best extragalactic “windows” between the foregrounds ? -solar system : zodi cloud scattering solar radiation, zodi emission -interstellar dust emission in the FIR 29/10/2015

8. high latitude sky emission 21 Sept 2010 - Orsay Hervé Dole, IAS - HDR - la nuit n'est pas noire 8 Leinert et al., 1997, A&ASS

9. integrated emission of galaxies: visible vs infrared output the heavy elements (and associated dust) abundance in the universe is increasing with time a naïve view would thus predict a decreasing FIR/visible ratio with redshift a few galaxies had been shown to have a large ratio but the bulk of the galaxies were expected to have rather small one (a few percent) some marginal measurements (rocket from M. Harwit’s group and balloon observations by Frank Low near the galactic center and Olthof and van Duinen along the galactic ridge of the Milky Way had shown signs of the strong diffuse FIR emission which were not well accepted 29/10/2015

10. FIR diffuse galactic emission was measured in a balloon experiment (AGLAE) using 2K cooled bolometers with NEP of 2 10 -14 W/ rt Hz - 40% of the luminosity of our galaxy comes out in FIR - IRAS showed that 1/3 of the energy output of galaxies in the local universe comes out in the FIR (Soifer,Neugebauer,Houck 1987,ARAA 25,187) -IRAS also found a class of luminous star burst IR dominated galaxies (IRAS 10214 was at the time the second most luminous object in the universe) 29/10/2015 Serra, et al, 1978, (ApJ 222, L21, ), 1979 Serra et al (A&A 50,247 ), Gispert, et al 1982, (A&A 106,293 ) Caux et al 1984 ( A&A 137,1)

11. SED and luminosity function of infrared galaxies the mid infrared emission from the ISM in our galaxy and in other galaxies was interpreted as due to out of equilibrium emission by very small grains and PAHs (Puget, Leger 1989 ARAA, 27,161) the PAHs molecules emit mostly at 6-9 and 12-15 µm ISO detected a large number of galaxies at 15 µm with a peak around 1 mJy which could only be due to the redshifted 6-9 µm emission of a strongly evolving population of luminous galaxies (10 11 L o ) at z about 1 this was implying a surprising result that the IR/visible output ratio was incresing with redshift Lagache et al 2003 (MNRAS, 338,555 ), Lagache, Puget, Dole 2005 (ARAA 43 727) later SPITZER was shown to be affected by a similar phenomenon at 24 µm (E. Le Floc’h, H. Dole) 29/10/2015

12. High |b| average: T d =17.5 K,  N H ) 250  m =10 -25 cm 2 (Boulanger et al 1996 A&A 312, 256) Interstellar Cirrus spectrum for a column density of N H =10 20 cm -2 IRAS/COBE/ISO IRAS DIRBE FIRAS ISO CIB 29/10/2015

13. –Detect LIRGs and ULIRGs up to z~3  PAH features passing through the filter First results: -SWIRE, Guaranteed time obs., FLS - L= 5 10 11 -10 14 L  @ z=1-3 - z med ~1 (~30% z>1.5) -Starburst. At high z, SFR>500M  /yr (e.g. Lonsdale et al. 04, Le Floc’h et al. 04, Yan et al. 04, 05, Bell et al. 05) Galaxies at z>1 : SPITZER (24  m) Caputi et al. 2005 29/10/2015

14. 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 S 24 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 29/10/2015

15. star formation history and CIB: implications of this evolution of our understanding of galaxy evolution normal galaxies emit typically one half of their energy in the mid and FIR (large dust grains + VSG-PAHs) the FIR/visible ratio increases from z=0 to 1 the L * of the galaxies dominating the integrated emission increases with redshift (by one order of magnitude from 0 to 1) the visible light traces the old low mass stars, the FIR traces the UV of the massive stars absorbed by dust thus the star formation rate the FIR and submm CIB traces the star formation rate and should peak around 150 µm and the best wavelength to detect it is near the minimum between the ISM emission and the CMB (300 µm). the near IR CIB could trace the very early galaxies near reionization (Ly alpha at z=10-15) which could be detected near the minimum between the zodi scattering and emission (2-3 µm) 29/10/2015

16. the detection of the CIB with FIRAS detecting an isotropic background is notoriously difficult; astronomers like to do differential measurements not absolute ones although on COBE the DIRBE experiment was planned for the detection of the CIB and the FIRAS was planned to measure the CMB and its main foreground spectra (ISM dust) it seemed in the mid 90s the best instrument for the detection for the CIB absolute measurements means black bodies filling the beam to calibrate and excellent control of straylight from far side lobes 29/10/2015

17. the problem was not the sensitivity of FIRAS but the component separation problem, remember that the first CMB spectrum with 10 4 signal to noise shown at the ASS in Washington was with 7 minutes of data ! the NEP of the 4 bolometers was about 10 -14 W/rt Hz but FIRAS was a double difference polarizing FTS spectrometer with a very large throughput two schools of thinking were opposed on this question: –use of the COBE data alone because the astrophysical data were not controlled well enough –use of a tracer of the diffuse ISM at high latitude (HI 21 cm survey with very good correction for far side lobes contribution: the Burton & Hartmann Dwingeloo survey) -for the near IR the main problems were the faint stars and the zodiacam scattering and emission - 29/10/2015

18. The dust/gas correlation at high Galactic latitude, F. Boulanger et al 1996, (A&A 312, 256). Tentative detection of a cosmic far-infrared back-ground with COBE, J.L. Puget et al : 1996, (A&A 308, L5), Fixsen et al 1998 (ApJ 508 523) 29/10/2015

19. CIB: Les fluctuations Distribution spectrale des galaxies IR: Redshift: différentes contributions aux différentes => Décorrélation des fluctuations d’une à une autre z= 0.1, 0.5, 1, 3, 5, 10 29/10/2015

20. modèle: CIB SED et contributions 29/10/2015 Béthermin et al., 2011, to be submitted H. Dole

21. Zodiacal scattered and emitted spectrum Interstellar at high latitude COBE DIRBE and FIRAS residuals after foregrounds removal 29/10/2015

22. quelles galaxies contribuent à l’EBL ? 29/10/2015 Lagache, Puget, Dole, 2005, ARAA x3 spectre de galaxie infrarouge redshifté

23. From M. Griffin Stacking w/ S 24 >0uJy Cosmic Infrared Background 29/10/2015 Dole et al 2006, A&A 451, 417

24. Extragalactic Background Light COBCIB COB/CIB ~1.0 COB~ 20 to 35 CIB~ 24 to 27 Dole et al., 2006, A&A, 451, 417 29/10/2015

26. The 6 fields studied by Planck for CIB note that Planck HFI has 52 bolometers with NEP 10 -17 W/rt Hz 29/10/2015

28. evolution of galaxies: luminosity function vs mass function The luminosity function shows rapidly increasing L * with redshift (Bettermin, 2010) at z> 0.5 the FIR luminosity per comoving volume becomes larger than the optical-UV one the FIR traces the star formation not the stellar mass already formed so far up to z around 3 the FIR still dominates the radiation output 29/10/2015

29. Open questions what is the redshift at which the FIR per comoving volume start to decrease sharply ? Why the star formation rate is not high within the baryonic matter in collased DM halos of 10 9 M o near the reionization redshift ? says differently why Kennicut’s law breaks down at high z ? these questions are difficult to answer because summ observations lack sensitivity and resolution to find the very distant FIR galaxies (except ALMA !) the CIB anisotropies might give us the answers before these ALMA deep surveys are carried out: Planck, ACT, SPT,…. 29/10/2015

31. CIB opacity to TeV gamma rays Photon-photon interaction can produce pairs if E.  > 2 (m e c 2 ) 2 1 TeV  1eV or 1 µm Flares have been observed in 6 Blazars by HESS. The analysis of the absorption in their spectra gives constraints on the CB in the optical and IR Can be done to get an absolute upper limit on the CB at a given frequency or assume a shape and give a limit on its normalization. This method is very useful when deep counts are already available. The Gamma rays give a tool to check if there is or not a missed component 29/10/2015

32. modèle: CIB SED et contributions 29/10/2015 Béthermin et al., 2011, to be submitted