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Mid-Infrared Observation of High Redshift Galaxy Evolution

Mid-Infrared Observation of High Redshift Galaxy Evolution. Alexandra Pope (UMass Amherst) JWST Workshop – STScI Baltimore June 8, 2011. Most star formation activity occurs behind dust . Lagache et al. 2005. Chary & Pope 2011. Bouwens et al. 2009.

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Mid-Infrared Observation of High Redshift Galaxy Evolution

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  1. Mid-Infrared Observation of High Redshift Galaxy Evolution Alexandra Pope (UMass Amherst) JWST Workshop – STScI Baltimore June 8, 2011

  2. Most star formation activity occurs behind dust Lagache et al. 2005 Chary & Pope 2011 Bouwens et al. 2009

  3. Most stellar mass and AGN growth occurs at z~1-3 sub-mm QSOs Squares: optical/near-IR Circles: far-IR/sub-mm Dickinson et al. 2003 Wall et al. 2008

  4. Most of the z~1-3 stellar mass growth occurs in LIRGs (and ULIRGs) Le Floc’h et al. 2005 Total Normal LIRGs ULIRGs

  5. Most of the z~1-3 stellar mass growth occurs in LIRGs (and ULIRGs) Murphy et al. 2011

  6. Ultra-luminous infrared galaxies (ULIRGs) “A rose by any other name would smell as sweet ” z ~ 2 Local DOGs • Complete samples of galaxies down to a given LIR • Not biased by AGN, dust temperature, detection limit, etc. • Mostly major mergers SMGs Bump sources C-thick AGN ? BzKs OFRGs

  7. Ultra-luminous infrared galaxies (ULIRGs) “A rose by any other name would smell as sweet ” z ~ 2 Local DOGs • Complete samples of galaxies down to a given LIR • Not biased by AGN, dust temperature, detection limit, etc. • Mostly major mergers SMGs Bump sources C-thick AGN ? BzKs OFRGs

  8. SubmillimeterGalaxies (SMGs) Pope et al. 2005 • high redshiftz~2 (Chapman et al. 2005, Pope et al. 2005) Borys et al. 2005 • massive Mgas~3·1010M M~1011M(Greve et al. 2005, Borys et al. 2005) Chapman et al. 2005 • high IR luminosities => SFR~1000Myr-1 …assuming no AGN! (Lilly et al. 1999, Chapman et al. 2005,Pope et al. 2006) sub-mm

  9. Spectral energy distribution (SED) ofhigh redshiftsubmillimeter galaxies (SMGs) Herschel • Circa 2011: Well sampled SED forULIRGs z~1-3 • Spectroscopy can provide a probe of the underlying radiation field • Mid-IR spectroscopy is sensitive to dust which is dominating the SFRD MIPS SCUBA Luminosity density (WHz-1) IRS VLA IRAC HST Rest Wavelength (m)

  10. Outstanding issues: Projects for JWST • Resolve the 24μm background – detect warm dust in faint LBGs which contribute significantly to the IR background; SMGs out to z~7 • Detect PAH emissionin lower luminosity galaxies (<1012Lsun) and/or out to z~7 -trace SF and ISM • Resolve PAH emission at z~1-3 (?) • Probe lower luminosity, obscured AGN in (U)LIRGs- High ionization lines Rigby talk • Trace shocks and turbulence in galaxies - Warm H2emission Guillard talk

  11. Outstanding issues: Projects for JWST • Resolve the 24μm background – detect warm dust in faint LBGs which contribute significantly to the IR background; SMGs out to z~7 • Detect PAH emissionin lower luminosity galaxies (<1012Lsun) and/or out to z~7 -trace SF and ISM • Resolve PAH emission at z~1-3 (?) • Probe lower luminosity, obscured AGN in (U)LIRGs- High ionization lines • Trace shocks and turbulence in galaxies - Warm H2 emission Imaging

  12. Deep Spitzer MIPS 24μm surveys Figure from M. Dickinson Spitzer GOODS Legacy Survey

  13. Deep Spitzer MIPS 24μm surveys • Secure detections* account for 70% of the 24μm background (Papovich+04, Chary+04) e.g. Counterparts to submillimeter galaxies (SMGs) out to z~4 (Pope+06) e.g. Detect warm dust in 2/3 of LBGs(Reddy+08) *Reach the confusion limit at ~60μJy (5σ, Dole+2004) Spitzer GOODS Legacy Survey

  14. Deep Spitzer MIPS 24μm surveys • Secure detections* account for 70% of the 24μm background (Papovich+04, Chary+04) e.g. Counterparts to submillimeter galaxies (SMGs) out to z~4 (Pope+06) e.g. Detect warm dust in 2/3* of LBGs(Reddy+08) *Reach the confusion limit at ~60μJy (5σ, Dole+2004) Pope et al. 2006, 2008

  15. Many star forming galaxies still missing from deep 24μm surveys Bouwens et al. 2009 Reddy et al. 2010

  16. Deep JWST MIRI 24μm surveys 7 times the spatial resolution of Spitzer • Resolve >99% of the 24μm background (Dole+2004) e.g. Counterparts to all submillimeter galaxies (SMGs) out to z~7 e.g. Detect warm dust in 100% of LBGs e.g. A few surprises? Simulated JWST image

  17. Outstanding issues: Projects for JWST • Resolve the 24μm background – detect warm dust in faint LBGs which contribute significantly to the IR background; SMGs out to z~7 • Detect PAH emissionin lower luminosity galaxies (<1012Lsun) and/or out to z~7 -trace SF and ISM • Resolve PAH emission at z~1-3 (?) • Probe lower luminosity, obscured AGN in (U)LIRGs- High ionization lines • Trace shocks and turbulence in galaxies - Warm H2 emission Spectroscopy or narrow-band imaging

  18. (ISO) Mid-infrared Spectroscopy Local ULIRGs Genzel et al. 1998 Lutz et al. 1998

  19. Spitzer IRS spectroscopy Detailed studies of local galaxies Smith et al. 2007

  20. Spitzer Mid-IR Spectroscopy Extending out to high redshift The mid-IR spectrum can be decomposed into two main components: 2. AGN:power-law + extinction Starburst: Polycyclic aromatic hydrocarbons (PAH) emission lines + extinction Main lines at 6.2, 7.7, 8.6 and 11.3m Weedman et al. 2006

  21. z~2 SubmillimeterGalaxies (SMGs) • high IR luminosities => SFR~1000Myr-1 …assuming no AGN! Local ULIRGs show increasing AGN contribution with LIR => Does this mean SMGs are AGN dominated ? SMGs SB fraction Log [LIR(L)] Tran et al. 2001

  22. Spitzer Mid-IR Spectroscopy of SMGs Starburst:Polycyclic aromatic hydrocarbons (PAH) + extinction SMG composite spectrum Mid-IR SED of SMGs is starburst dominated : small contribution from AGN (<30% at these wavelengths) Scaled up M82 – not like local ULIRGs (e.g. Arp220) Pope et al. 2008 see also Valiante et al. 2007, Menendez-Delmestre et al. 2009 AGN:power-law + extinction

  23. SMGs are scaled up local starbursts SMGs(Pope et al. 2008) Local BGS ULIRGs(Armus et al. 2007) Local SB(Brandl et al. 2006) Pope et al. 2008

  24. Spitzer-selected ULIRGs Spitzer-selected (U)LIRGs at z=1 and z=2 also show higher PAH EW than local ULIRGS Stronger PAH emission at high redshift (for a given LIR) Fadda et al. 2010

  25. IRS-identified Compton-thick AGN • Strong power-law continuum (f-2) • No X-ray detection! • Compton-thick AGN: NH >> 1024cm-2 See Alexander et al. 2008 for more discussion on IRS identified Compton-thick AGN Pope et al. 2008

  26. What about lower luminosity galaxies? Siana et al. 2008, 2009; see also Rigby et al. 2008, Gonzalez et al. 2010

  27. JWST/MIRI spectra of z~2 LIRGs • Spitzer IRS took spectra of ~200 galaxies at z>1 - the majority of these are ULIRGs, with a few LIRG – learnt a lot of AGN vs SF in the most luminous galaxies • JWST/MIRI will be able to take spectra of all LIRGs and at much higher spectral resolution (R~3000!) Spitzer high resolution (R~600) only possible for local galaxies Armus et al. 2007

  28. Getting more info out of a PAH spectrum Relative PAH strengths tell you about the size distribution and ionized state of the dust grains; compared to large grains you can constrain the strength of the radiation field Draine & Li 2007 Smith et al.2007

  29. Getting more info out of a PAH spectrum Draine & Li 2007 Pope et al. 2008

  30. JWST/MIRI spectra of z>4 galaxies? • Spitzer/IRS saw PAHs out to z~4 • JWST/MIRI will see the 6.2μm PAH out to z~3.5 and the 3.3μm PAH out to z~7 – track down the earliest dust and learn how it formed 24 hr Spitzer IRS spectrum of the z=4 SMG GN20 Riechers et al. in preparation

  31. 3.3μm PAH feature in local galaxiesEW provides a cleaner AGN indicator Imanishi et al. 2010

  32. 3.3μm PAH at high redshift Sajina et al. 2009

  33. What if SMGs are really powered by AGN? • In order to have most of the LIR from the AGN andhave the PAHs survive, you need to have an unusual geometry, e.g. non PAH dust shielding more PAH dust from AGN radiation or just really extended distribution of small grains • Can we resolve this??

  34. What if SMGs are really powered by AGN? • SMGs have sizes of : ~0.6 arcsec ~5kpc (Engel+10, Younger+08) • JWST/MIRI has a resolution of 0.3 arcsec at 10μm – we can try to resolve the 3.3μm PAH emission in galaxies at z<2 • Compare to distribution of large dust grains as traced by ALMA

  35. Warm molecular HydrogenTraces shocks and turbulence Gonzalez et al. 2010

  36. Synergy with Herschel, ALMA and other (sub)mm facilities • We need to plan JWST program that will complement other capabilities and facilities circa 2017/2018: • Herschel will have provided a statistic samples of high redshiftULIRGs • ALMA will be underway “detecting molecular gas in Milky Way like galaxies out to z~3” – but on smaller targeted samples • Large single dish (sub)mm telescopes (LMT, CCAT) can provide statistical samples of LIRGs – only probing the cold dust

  37. Herschel Space Observatory • Deep high(er) resolution far-IR imaging at: 70, 100, 160, 250, 350, 500μm • Accurate LIR and SFR for individual galaxies • Dust properties: Tdust, β, Mdust GOODS Herschel Key Program PI David Elbaz

  38. GOODS Extragalactic Mid-IR Spectral Library • 150 sources in GOODS-N and ECDFS observed with Spitzer/IRS • All data reduced and lines measured in a uniform way • Spectral decomposition to get AGN fraction, LPAH, L8, etc. AGN < 50% AGN > 50%

  39. SED fitting withSpitzer/IRS + Herschel data AGN dominated (mid-IR) SF dominated (mid-IR) Warm dust (100K) Cool dust (~30K)

  40. Composite SEDs Kirkpatrick et al. in prep

  41. Composite SEDs Kirkpatrick et al. in prep

  42. Influence of the AGN on IR colors Kirkpatrick et al. in prep Hatziminaoglou al. 2010

  43. Synergy with ALMA: Constraining ISM conditions Valtchanov et al. 2011

  44. Synergy with ALMA: Constraining ISM conditions X LPAH Valtchanov et al. 2011

  45. Summary • We have learnt a lot from Spitzer – this puts us in a great position to plan innovative projects for JWST • Several key areas where still have a lot to learn about dust in high redshift galaxies: • Directly detect dust in the galaxies which dominate the SFRD • Understand the detailed composition of dust at high redshift which constrains the production mechanisms • Relative heating of dust from starbursts and AGN activity • JWST together with ALMA will be a powerful duo for attacking these problems

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