MIPS Observations of Galaxies, Near and Far

1. MIPS Observations of Galaxies, Near and Far

2. G. H. Rieke (University of Arizona), for Almudena Alonso-Herrero (CSIC) Lei Bai Eric Bell (MPIA) Karina Caputi (IAS) Hervé Dole (IAS) Jennifer Donley Eiichi Egami Chad Engelbracht Karl Gordon Dean Hines Joannah Hinz Emeric LeFloc’h Gerry Neugebauer Casey Papovich Pablo Pérez González Marcia Rieke Jane Rigby Yong Shi Xianzhong Zheng (MPIA)

3. Galaxies Near and Far • Even SimpleGalaxies are Complex! Example of M31 • High-z Star Formation: Relevant Properties from Nearby Galaxies • How doesmetallicity affect galaxy spectral energy distributions? • What powers the far infrared emission in galaxies? • How can we calibrate the star formation rate from infrared measurements? • High-z Star Formation: Relevant Properties from Far-Away Galaxies • How many hidden AGN might be confused with star forming galaxies? • Given confusion limits, how can we get far-infrared properties of high-z galaxies? • If we knew all the answers, we could determine star forming properties at high-z well!! • High-z Star Formation with MIPS • How do the new “Madau” plots look? • Does the star formation vs. redshift match our models? • What happens at low luminosity? • What kinds of galaxies dominate the SFR?

4. M31 Beck et al.

5. M31 Thilker et al.

6. M31 Guélin et al.

7. M31 Devereux

8. M31 MIPS GTO

9. M31 MIPS GTO.

10. M31 2MASS

11. M31 APOD/J. Ware

12. M31 GALEX

13. M31 X-Ray ROSAT

14. Stars, Dust, and Gas in M31 Complexities show that abstracting to an unresolved point is error-prone! (Karl Gordon et al.) Stars blue = UV green = red red = J-band Dust blue = 24mm green = 70mm red = 160mm Gas blue = CO green = HI red = Ha

15. High Redshift Galaxies: Relevant Properties from Nearby Galaxies • Behavior of “Polycyclic Aromatic Hydrocarbon” • features with metallicity • PAHs may dominate Spitzer signals at 24mm out to z ~ 3 • A change with metallicity/redshift would affect interpretation • of high-z results • Dramatic change seen at O/H ~ 25% solar • What powers the far infrared emission in galaxies? • Is it powered by the youngest stars? Interstellar radiation field? • Close correspondence on all scales of Ha, 24 & 70mm • 160mm has different distribution, power source less clear (ISRF?) • Calibration of star formation rate vs. infrared emission • Find close correlation between extinction-corrected Paschen a • and 12mm, 24mm, and total far infrared

16. Behavior of “Polycyclic Aromatic Hydrocarbon” features with metallicity

17. Individually Detected ULIRGS have SEDs Like Local Ones Eiichi Egami et al. “PAH” features dominate rest frame SED, ~ 7 to ~ 9mm. Hence, dominates Spitzer 24mm signals for 1 < z < 3 PAH missing in AGN

18. Behavior of PAH Features with Metallicity Chad Engelbracht et al. • IRAC and MIPS colors can be combined to identify PAH emission • Subtract “stars” @ 3.6mm off 4.5mm, ratio to 8mm and compare with 8/24mm • SED models including PAH feature agree with locus of galaxies with • spectroscopically • confirmed • features

19. Behavior of PAH Features with Metallicity • IRAC and MIPS colors can be combined to identify PAH emission • Subtract “stars” @ 3.6mm off 4.5mm, ratio to 8mm and compare with 8/24mm • SED models including PAH feature agree with locus of galaxies with • spectroscopically • confirmed • features • Galaxies without • PAH features • occupy a • different region

20. Behavior of PAH Features with Metallicity • IRAC and MIPS colors can be combined to identify PAH emission • Subtract “stars” @ 3.6mm off 4.5mm, ratio to 8mm and compare with 8/24mm • SED models including PAH feature agree with locus of galaxies with • spectroscopically • confirmed • features • Galaxies without • PAH features • occupy a • different region • Other galaxies • divide into two • areas, similar to • those with • spectral data

21. PAH Feature Disappears Abruptly at ~ 25% Solar Metallicity • Use photometric technique to separate PAH SEDs from non-PAH ones • Plot metallicity vs. 8/24mm • Separation in 8/24 predicted from previous plot • Find non-PAH SEDs lie below 25% solar O/H • (or 12 + log (O/H) < 8.2) • Probably not an • issue to z ~ 3 • for the highly • luminous galaxies • that can be • reached with • Spitzer

22. (This figure differs from the similar one shown by Jessica Rosenberg because it goes to much lower metallicity) Caution: individual “low metallicity” galaxies may have regions of higher metallicity due to localized star formation! SBS0335

23. What powers the far infrared?

24. What powers the far infrared? M33 before Joannah Hinz et al. Detailed image comparison shows that compact 24 & 70mm emission is entirely from HII regions.

25. Low pass filtering isolates the extended emission M33 after

26. M33 after Extended 24mm and 70mm are virtually identical to extended Ha.

27. M33 after Extended 24mm and 70mm are virtually identical to extended Ha. 160mm is distinctly different

28. 160mm is a good match to filled aperture radio M33 160mm Effelsberg 17cm

29. Extended PAH and 160mm are morphologically similar to extended non-thermal radio; powered by diffuse interstellar radiation field from modest-age stars (recall Dopita talk) 8-3mm M33 J. Hinz

30. Low Surface Brightness Galaxy UGC 10445 Has Extended Cold Halo at 160mm (Joannah Hinz et al.) a. 3.6mm b. 4.5mm c. 5.8mm d. 8mm e. 24mm f. 70mm g. 160mm

31. Radial Profiles Clearly Show the Low Temperature Halo • Lower two frames show the • observed radial • profiles at 24 and 70mm • Upper frame shows 160mm • profile, plus 3.6 and • 24mm ones convolved to • the 160mm resolution • The 160mm “halo” extends • well beyond the galaxy • as defined at the two • other wavelengths • It is not yet understood • what is warming the • dust so far from the • galaxy

32. Calibration of star formation rate vs. infrared emission

33. Correcting from 24mm to Far Infrared/Total Infrared Can Introduce Significant Errors in Star Formation Rates Based on FIR/TIR Based on nearby galaxy SEDs, there are large uncertainties in extrapolating an observed 24mm flux density to either a 70mm one, or to total infrared output. From Danny Dale et al.

34. However, Accurate SFRs Can Be Determined from Mid-IR Alone Extinction-corrected Paschen a correlates very closely with 24mm flux density in M51 (Daniela Calzetti et al.) Recall the behavior in M33, where we found that Ha and 24mm flux density have identical distributions over the galaxy.

35. Accurate SFRs Can Be Determined from Mid-IR Alone • A tight correlation is also seen between extinction-corrected • Paschen a and 12mm (from IRAS) flux density for normal galaxies • and LIRGs (at least up to 5 X 1011 Lsun). • The correlation is of similar quality to that with total IR and the • dispersion is small. (from Almudena Alonso-Herrero et al.)

36. High Redshift Galaxies: Relevant Properties from Far-Away Galaxies • How many hidden AGN might be confused with • star-forming galaxies? • Sample of 27 galaxies in 2Msec region of CDFN selected as • AGN from radio/24mm properties - independent of X-rays • 16 of the 27 are not cataloged as X-ray sources • 5 - 7 are not detected even at 2-s level • Sample of ~ 100 power law galaxies in CDFS has ~ 40% • not detected in X-ray • Given confusion limits, how can we get far-infrared • properties of high-z galaxies? • How can one associate 70 & 160mm sources with 24mm ones? • 70 & 160mm identifications of 24mm sources account • for > 75% of total 70 & 160mm infrared background • Validates using 24mm sources to locate 70 & 160mm ones

37. How many hidden AGN might be confused with star-forming galaxies?

38. Identification of X-Ray-Free AGN Jennifer Donley et al. • Galaxies too bright in radio for star-forming IR/Radio ratio have AGN • Allows identification of AGN sample without using X-ray selection Star-forming galaxies and radio-quiet AGN

39. Identification of X-Ray-Free AGN Jennifer Donley et al. • Galaxies too bright in radio for star-forming IR/Radio ratio have AGN • Allows identification of AGN sample without using X-ray selection Radio-loud and radio-intermediate AGN

40. Of 27 AGN selected this • way with > 1 Ms Chandra • exposure, 16 are not • listed in CDFN catalog • 9 more are detected at the • 2 to 5-s level • 5 are not detected, even • with stacking to achieve • exposure of > 7Ms • 2 more are undetected but • may be confused • SEDs of X-ray faint objects • (left) are indistinguishable • from X-ray bright ones • (right) • All are dominated by stars, • Half are detected at 24mm

41. Of 27 AGN selected this • way with > 1 Ms Chandra • exposure, 16 are not • listed in CDFN catalog • 9 more are detected at the • 2 to 5-s level • 5 are not detected, even • with stacking to achieve • exposure of > 7Ms • 2 more are undetected but • may be confused • SEDs of X-ray faint objects • (left) are indistinguishable • from X-ray bright ones • (right) • All are dominated by stars, • Half are detected at 24mm • In CDFS, ~ 100 sources • detected at 24mm and • with power law SEDs in • IRAC bands • 40% are not detected in • X-ray (even in center of • Chandra field) (Almudena • Alonso-Herrero et al.)

42. Given confusion limits, how can we get far-infrared • properties of high-z galaxies?

44. Stacking on 24mm positions yields strong detections at 70 and 160mm

45. Stacking on 24mm positions yields strong detections at 70 and 160mm

46. With stacking, most of the far infrared background is resolved

47. S(24mm) 24mm 70mm 160mm > 80mJy 70% 75% 63% > 30mJy* >77% >84% >74% * 24mm detection is very incomplete at this flux density Using 24mm Detections to Probe Far Infrared Galaxy Properties • Stacking on the 24mm positions yields a detection in an average • sense accounting for ~75% of the cosmic background in both • far infrared bands • Validates using 24mm sources to locate 70 & 160mm ones • (although a few objects have very large 70/24 flux ratios)

48. High-z Star Formation with MIPS • How do the new “Madau” plots look? • No surprises, error range is coming down • Does the star formation vs. redshift match our models? • No! • What happens at low luminosity? • Luminosity function is similar to local one • What kinds of galaxies dominate the star formation? • To z ~ 1.5, dominated by LIRGs • For z > 1.5, ULIRGs important, SEDs similar to local ones • (with significant contamination from AGNs) • z ~ 1 LIRGs have similar morphology to local ones, • z ~ 1 LIRGs also have similar morphology to z ~ 1 IR-inactive ones • Suggests LIRG-level activity accompanies a certain level of asymmetry • This asymmetry is common at z ~ 1 (and rare locally), consistent with • LIRG-level star formation episodes also being common there

49. How do the new “Madau” plots look?

50. Evolution of Comoving IR Energy Density Emeric leFloc’h et al. Green is total, blue is galaxies below 1011 Lsun, yellow is LIRGs (1011 < L < 1012) and red is ULIRGs (1012 < L). Solid line evolves as (1+z)3.9 Dashed line is UV without extinction correction, dotted line is IR+UV