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FORMATION AND EVOLUTION OF GALAXIES FROM INFRARED AND RADIO SURVEYS

FORMATION AND EVOLUTION OF GALAXIES FROM INFRARED AND RADIO SURVEYS. Carlotta Gruppioni (INAF-OABO) Bologna 1 Ottobre 2007. SUMMARY. Advantages of IR and radio IR & radio emission from galaxies Early galaxy evolution results in IR and radio: source counts & luminosity function

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FORMATION AND EVOLUTION OF GALAXIES FROM INFRARED AND RADIO SURVEYS

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  1. FORMATION AND EVOLUTION OF GALAXIES FROM INFRARED AND RADIO SURVEYS Carlotta Gruppioni (INAF-OABO) Bologna 1 Ottobre 2007

  2. SUMMARY • Advantages of IR and radio • IR & radio emission from galaxies • Earlygalaxy evolution results in IR and radio: source counts & luminosity function • Recent results from Spitzer • IR galaxy evolution within the Cosmological context

  3. Observing in the IR ad radio bands

  4. Why InfraRed and Radio? • With MIR/FIR/radio we can approach the history of galaxy formation on the basis of the instantaneous Star-Fromation Rate (SFR), in fact • MIR/FIR and radio are good indicators of recent star-formation (SF), while • NIR is a tracer of evolved stellar populations and is better suited for studying the history of mass assembly

  5. WHY INFRARED? • Infrared explores the hidden Uiverse (obscured by dust) • Infrared provides access to many spectral features (emission and absorption bands of molecules) • Infrared probes the early life of cosmos (early stages optical energy shifted to IR)

  6. Galaxies Emission in the Mid-InfraRed (MIR):5 – 40 μm MIR band • ) Unidentified Infrared Bands(UIBs) at 6.2, 7.7, 8.6, 11.3 and 12.7µmproduced bypolycyclic aromatic hydrocarbons (PAH) heated by stellar photons • ) Warm Dust(Very Small Grains, VSGs, at T > 150 K): originates a rapidly increasingcontinuum(at 10 m)

  7. Galaxy Emission in the Far-InfraRed (FIR): 40-500 μm To the first orderFIRemissionin galaxies is due tothermal radiation from dust grainsheated bystellar photons(component associated to recent SF): LFIR = 4 D2 S() d / [1-e -] + a“cirrus”component(up to50%in theless active spirals) heated by theISM

  8. Radio Emission from Galaxies • ) Synchrotron radiation from relativistic e- accelerated by supernova remnants (SNR) • LNTSN  -( =( -1)/2; N=N0 E- ) • 2) Free-free emission from HII regions • LT Q(H) Te 0.45 -

  9. Thermal radiation sincrothron free-free (Condon 1992, ARA&A, 30, 57)

  10. Stars of mass > 5-8 M (average life  3×107 yr) produce SN II and Ib, whose remnants accelerate the e-. The same stars are also responsible for ionizating the HII regions. Radio observations are tracers of very recent star formation in galaxies. 1) radio non produced by stellar populations older than 108 yr 2) high positional accuracy to identify star-formation regions 3) transparency with respect to intense starbursts

  11. The radio/IR correlation The radio-FIR correlationis locally well assessed, over a wide range of luminosities, from normal spiralstoULIGs:q = log(FIR/3.75 1012 Wm-2)-log(S1.4/Wm-2 Hz-1) where FIR=1.26 10-14(2.58 S60/Jy + S100/Jy) Is the flux between40 and 120 m qmed 2.34, q=0.27 (Yun, Reddy & Condon, 2001, ApJ, 554, 803)

  12. The radio-FIR correlation seems to hold at least up to z=1 (Yun et al. 2001; Elbaz et al. 2002; Gruppioni et al. 2003) 0.1 < z < 0.7 z  0

  13. ISOCAM 15-μm luminosity has been found to correlate with the radio (1.4-GHz) one at least up to z~1(Elbaz et al. 2002; Gruppioni et al. 2003), while the higher sensitivity gained by the Spitzer 24-μm observations has shown that the radio-MIR correlation holds up to z~2(Appleton et al. 2004).

  14. This result is a strong constraint for the evolution of IR and radio star-forming galaxies (and for the Cosmic SFH). • However, the FIR-radio correlationis not understood in detail, neither is the linear relationship between the non-thermal radio emission and the star-formation rate!!!

  15. STAR FORMATION INDICATORS Visibility regions : z ≤0.5 for Hα z ≤ 1.7 for [OII] 0.2 ≤z ≤ 2.3 for UV • Salpeter IMF : 0.1 < M < 100 Mʘ • radio, Condon (1992) • FIR, Kennicutt (1998) SFR(FIR) = L(FIR) / 2.22 ×1036W •optical, Kennicutt (1998) λ(UV)=2800Å λ(Hα)=6562Å λ([OII])=3727Å

  16. Comparison between different SFR indicators Better correlation between SFR(radio) and SFR(FIR) (top) than between SFR(radio) and SFR(Ha) (middle) and SFR(UV) (bottom): Radio and FIR not affected by DUSTlike Hα and UV!!! SFR (FIR) SFR (Hα) SFR (UV) SFR (radio) Cram 1998, ApJ, 507, 155

  17. The IR Universe: from IRAS to ISO and SPITZER • IRAShas explored the local Universe(z < 0.2)in theIR (10 – 200 μm), showing that 30% of the energetic output from galaxies emerges in these bands. • IRAShas discovereda new class of galaxiesemitting the bulk of their energy in the infrared: the majority of them areDUSTY starburst galaxies (+AGN?).

  18. Thanks to IRAS we know that galaxies forming stars at > 20 M/yr radiate the bulk of their luminosity above 5 m: LIGs: 11  log(LIR/L)  12 ULIGs: 12  log(LIR/L) 13 HyLIGs: 13  log(LIR/L) WereLIGs/ULIGsmore numerous in the past?Aredistant LIGs/ULIGssimilar to local ones? What do they teach us about star- and galaxy-formation connections?

  19. From IRAS to ISO… With ISO (0.65-m tel.)deep MIR surveys for distant galaxies have been carried out for the first time (especially in the LW3 ISOCAM filter:12 - 18 µm). With> 1000times better sensitivity than IRAS,ISOCAMhas explored for the first time the Universe atz > 0.5in the Infraredband

  20. Nearly simultaneous discoveries… • from ISOCAMsurveys: excess of faint galaxies in source counts  galaxies were more IR luminous or more numerous in the past • Cosmic IR Background (CIB; Puget et al.96) at least as strong as UV-optical-NIR one • 850-mm SCUBA number counts excess of faint objects: even at large redshifts very large dust emission!

  21. Nature of ISOCAM galaxies Most are star-forming galaxies, often showing irregular/merging morphologies.  AGN <15-20% (Fadda et al. 2002) • from Shallow Surveys (i.e. ELAIS; La Franca, Gruppioni, Matute et al. ’04) : <L15> ~ 1010 L , <z> ~ 0.2 • from Deep Surveys (i.e. IGTES; Elbaz et al. ’99,’01) : <L15> ~ 1011 L , <z>  0.8 • LIG is an important phase in galaxy life: a galaxy might experience several bursts of intense SF < z > = 0.8 HDFN < z > = 0.2 ELAIS-S1

  22. Cosmic Evolution Several authors have produced backwards evolution models to reproduce source counts and redshift distributions of IR (ISO) galaxies and AGN i.e. Devriendt & Guiderdoni ’00; Dole et al. ’00; Chary & Elbaz ’01; Pearson ’01, ’05; Franceschini et al. ’01, ’03; Malkan & Stecker ’01; Xu et al. ’01, ’03;King & Rowan-Robinson ’03; Lagache, Dole & Puget ’03;Pozzi et al. ’04; Gruppioni et al. ‘05

  23. Cosmic Evolution All use a combination of luminosity and density evolution as a function of z and start from the local 15 or 60 µm LF The major output of these models was to showthat LIGs/ULIGs were much more commonin the pastthan they aretoday (i.e.Chary & Elbaz ’01:comoving IR luminositydue to LIGs ~ 70 times larger at z~1 than today) Pozzi et al. ‘04 Lagache et al.’04 Pearson et al. ’01 Franceschini ’01 Franceschini upd.

  24. Luminosity Function: Φ(z,L)(dV/dz)dzdL= number of galaxies in the differential comoving volume element (dV/dz)dz with luminosity between L and L+dL Maximum-likelihood method (Marshall et al. 1983, ApJ, 269, 35): minimize the function S = -2 ∑Ni=1ln Φ(zi,Li) +2∫∫Φ(z,L)Ω(z,L)Θ(z,L)(dV/dz)dz dlogL Search for the best-fitting parameters and simultaneously constrain the evolution by trying to reproduce the observables (source counts and redshift distributions)

  25. GAL Luminosity Function z-distribution normal spiral starburst Two galaxy components: Normal spirals (non-evolving): dot-dashed Starburst (evolving both in luminosity and density: L(z) ~ L(0)x(1+z)3.5 and (z) ~ (0)x(1+z)3.8 up to z=1 (Pozzi, Gruppioni, Oliver et al. 2004)

  26. AGN2 Luminosity Function z-distribution Luminosity Evolution: L(z) ~ L(0)x(1+z)2-2.6 up to z=2 (Matute et al. 2006)

  27. Main ISOresults ISO has shown that galaxy formation could not be understood without accounting for dust extinctionas a major ingredient. The ISOsurveys clearly established that extreme events such as those taking place in local LIGs and ULIGs must have been more common in the past  They can now be considered asa standard phasethat most galaxies experienced during their lifetime!

  28. What happens in the radio? The radio-IR correlation applying to μJy radio sources (up to z ~ 1in the HDFN) suggests that for most systems radio emission is generated by star formation processes. Star formation only begins to dominate at the faintest levels probed by deep radio surveys (<100 μJy): at the faintest fluxes (~40 μJy) star formation processes appear to account for about 2/3 of all radio emission (Garret et al. 2004).

  29. At S>0.1-0.2mJy 60% early-type (radio from AGN) (Gruppioni, Mignoli & Zamorani, 1999, MNRAS, 304, 199) At S>16 Jy80% starbursts (Richards, 2000, ApJ, 533, 611) late-type galaxies at low radio-optical ratios: R < 100 (R=S100.4 (mag-12.5))

  30. Rapid increase of a population of star-forming galaxies at faint radio fluxes Are they the same objects (LIGs) found in deep IR surveys?

  31. Difficult to test, since faint radio sources are very faint also in the optical: Use the results from IR Surveys and test through the radio-IR correlation the fractions of star forming galaxies at different radio flux levels

  32. Using the radio-MIR correlation IR star-forming galaxies contribution to thefaint radio counts (model)and cfr. withdata AGN

  33. Agreement between data and model: • MIRstarburst galaxies rapidly increase around 0.5-1 mJy and contribute >60% at S1.4 GHz < 0.05-0.1 mJy(in agreement withJy works: i.e. Richards 2000, ApJ, 533, 611,finding80%of starbursts atS1.4 GHz > 16 Jy) • Elliptical radio-galaxies/AGN dominate at S1.4 GHz > 0.1 mJy(in agreement withsub-mJy works: i.e. Gruppioni , Mignoli & Zamorani 1999, MNRAS, 304, 199,finding >60% of early-types atS1.4 GHz > 0.2 mJy)

  34. From ISOCAMto Spitzer... SpitzerTelescope is now providing new insight into the IR population of galaxies and AGN In particular with the MIPS 24-m band, which is starting to detect the high-z (z~1.5-3.0) analogs of the 15-m sources

  35. High redshift sources detected by • Spitzer in the mid- and far-IR range • (i.e. 8 μm ≤ λ ≤ 1000 μm) are • characterized by intrinsecally very high • Luminosities(Le Floc’h et al. 2004). • They appear as the distant analogs of the local LIGs/ULIGs • Spitzer will allow us to study the evolution of Star Formation across the Universe up to z~2.

  36. ... What is SPITZER finding in terms of galaxy evolution? FLS 24 µm: Marleau, Fadda, Storrie-Lombardi, et al. 2004 Galaxy evolution models: Franceschini et al. (2001) & Rodighiero et al. (2004): non-evolving normal pop, fast-evolving type-II AGNs & starbursts, evolving type-I AGNs Pozzi et al. (2004) Gruppioni et al. (2005) Lagache, Dole & Puget (2003):non-evolving normal spirals and starbursts with L density evolving with redshift IRAS data points (transformed to 24 μm) (Hacking & Soifer 1991; Sanders et al. 2003) No-evolution model normalized to IRAS counts

  37. Spitzer view on the evolution of star-forming galaxies from z=0 to z~3 (Perez-Gonzalez et al. 2005; Le Floc’h et al. 2005) data

  38. The infraredluminosity function of galaxies at z=1 and z=2 in the GOODS fields (Caputi et al. 2007) • Spitzer 24-µm selected galaxies in the GOODs fields (291 arcmin2) • AGN identified based on X-ray data and IRAC colours • derived rest-frame 8-µm and bolometric IR LF at z=1 and 2 • strong luminosity evolution between z=0 and z=1 (number density increases x250) almost constant between z=1 and z=2

  39. Star-Formation History from Galaxy evolution in the IR ρν(z)=∫0∞ LνΦ(Lν,z)dLν= luminosity density SFR L SFH = SF density vs. z obtained converting luminosity density to SF density

  40. .. up to z~3: SFR goes as (1+z)4to z=0.8 keeps rising with < slope to z=1.2 is almost constant to z=3 Perez-Gonzalez et al. 2005

  41. Bolometric IR luminosity density of galaxies dominated by LIGs at z<2, but ULIGs contribution increases at high-z: at z=2 same as that of LIGs • between z=0 and z=1 the IR Luminosity density increases as (1+z)3.1 • is almost constant between z=1 and z=2 Caputi et al. 2007

  42. Low-LIR systems (< 1011 L) main SF activity at z < 1 ULIGs (LIR > 1012 L) main activity phase at z > 1.5 Perez-Gonzalez et al. 2005 Intermediate LIR peak at 0.7<z<1.5  formation and evolution of galaxies has been a strong function of luminosity TOTAL SFR density LIR<1011 L LIR>1011 L ULIGs Le Floch et al. 2005

  43. Interpretation within the Cosmological Framework The SF results seem to indicate an inversion in the process of dynamical assembly of galaxies compared to the hierarchical expectations.  Possible explanation: to consider energy feedback by a nuclear AGN stopping gas accretion and star-formation in the most massive systems at high-z (Granato et al. 2004; Springel et al. 2005), while leaving it undisturbed in the lower mass galaxies where AGN activity is irrelevant (Franceschini et al. 2006).  Close relationship beween evolutionary history of star-formation and nuclear BH accretion in AGN.

  44. Problems With the present data is not possible a precise match of galaxy build-up and the growth of super-massive BHs: difficult to obtain an accurate census of obscured AGN phenomenon. In fact, even the inclusion of Spitzer data in detailed IR multiwavelength SED-studies is not sufficient to identify the obscured AGN population (Franceschini et al. 2005; Polletta et al. 2006; Gruppioni et al. 2007)  Preliminary results from X-ray surveys (Alexander et al. 2005): AGN and starburst activity occur concomitant in luminous high-z forming galaxies

  45. Does IR Reveal Hidden AGN Activity?(see Houck et al. 2004; 2005; Higdon et al. 2004; etc…) • Obscured AGN are needed: - to reproduce the X-ray background peak(Setti & Woltjer 1989, Comastri et al. 1995 etc. ) - Unified Models: dusty torus around AGN responsible for absorption of X-ray to NIR nuclear radiation - models predict that AGN activity in the past take place in “dusty” environments/systems • Need to separate AGN from stellar activity to: - Have a complete picture of galaxy(-AGN) formation and (co)evolution, since  Luminous Infrared Galaxies (LIGs) represent an active phase of star-formation and/or AGN activity and dominate the luminosity density at z>1 Main weakness of actual data : galaxy/AGN separation

  46. IR Spectra of local ULIGs From Spitzer-IRS (InfraRed Spectrograph): Galaxy SEDs evolve with Luminosity: increasing AGN contribution with increasing L (Charmandaris et al. 2004)

  47. IR colour selection Blue (unobs) Red AGN (unobs and obs) are expected to have warm power-law SEDs at>1 μm(≠ from elliptical/starburst) AGN Red (obs) AGN (both type 1 and 2) can be isolated in NIR/MIR diagrams νSν Blue Red SEVERAL IR colour-selection criteria proposed so far(i.e. Lacy et al. 2005; Stern et al. 2005; Barmby et al. 2006, etc.)  PROBLEMS: Completeness (are all AGN selected?) Reliability (are only AGN selected? How much galaxy “contamination”?) Elliptical Flat/Blue Red Starburst Optical NIR IRAC 3.6 4.5 5.8 8.0 NEEDComplete Multiwavelength Characterization

  48. Type 2 AGN Optical emission from Type 2 AGN can be diluted by the host galaxy • difficult to classify as AGN from optical line diagnostics. • Crucial range: near-/mid-infrared (NIR/MIR) where galaxy SEDs have a dip (2-5 m) and the hot dust heated by the AGN start contributing, filling up the dip. flat dusty torus emission dip

  49. Broad-band SEDs:MIR in excess with respect to expectations for galaxies SED well fitted byevolved stellar population (reproducing opt/NIR) +dusty torus heated by AGN (reproducing MIR/FIR) fit with starburst fit with elliptical+torus

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