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SFR and COSMOS

SFR and COSMOS. Bahram Mobasher + the COSMOS Team. COSMOS offers:. Extensive multi-waveband surveys from radio to X-ray Large area coverage ( 2 sq. deg.) HST/ACS morphologies (B/D, Sersic, concentration, asymmetry, clumpiness)

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SFR and COSMOS

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  1. SFR and COSMOS Bahram Mobasher + the COSMOS Team

  2. COSMOS offers: • Extensive multi-waveband surveys from radio to X-ray • Large area coverage ( 2 sq. deg.) • HST/ACS morphologies (B/D, Sersic, concentration, asymmetry, clumpiness) • Accurate photometric/spectroscopic redshifts and spectral types (from early-type to starburst) • Galaxy masses

  3. How COSMOS can help to understand: Physics of star fromation activity Nature of star forming galaxies Main parameters affecting the SFR

  4. Star Formation Rate • How different star formation diagnostics are compared ? • What is the role of galaxy mergers on SF activity ? • How the SFR changes with redshift for different morphologies of galaxies ? • Are dusty galaxies more actively star forming ? • How SFR depends on galaxy environment ?

  5. Low-zQ1:How are Different SF Diagnostics Compared ?

  6. UV (GALEX); U (CFHT); Ha (VLT); IRAC (Spitzer); MIPS(Spitzer); radio (VLA)

  7. UV Luminosity (GALEX) • Produced by young massive stars • Is directly proportional to SFR • Highly affected by dust extinction • Old population also contribute to the UV flux

  8. Ha Line (VLT/VIMOS) • Emission line produced by star-forming regions • Less affected by dust extinction • Can be used at high redshifts • Is directly correlated to SF activity

  9. Mid/Far-IR Luminosity (IRAC/MIPS) • FIR radiation is produced by absorption and re-emission of the UV light by dust • Mid-IR emission is produced by PAH features • Far-IR surveys provide an easy way to select unbiased samples of SF galaxies • Need to calibrate PAH features as a measure of SFR

  10. Radio Luminosity (VLA) • Produced by synchrotron radiation generated by electrons from Type II SNe • Indirectly is proportional to SFR • Not affected by dust extinction

  11. Q2: How the SFR is Affected by Galaxy Interaction/mergers ?Q3: How does this change in different environments and with redshift?

  12. Concentration • Most z<=1 optically selected starbursts have concentration indices which are significantly smaller than most early types • C>0.3 : 12 % SB, 18% Late, 73% E/Sa • Komogorov-Smirnov ( K-S) test • - SB vs Early type : 7e-7 (> 99.9%) • SB vs Late-type : 0.53 • Large C & galfit Sersic n=3-4 correlate AGN fraction : CDF-S X-ray catalog : 2% of SB host AGN vs >25% of Early types

  13. Asymmetry in rest frame B • 55 % of z<=1 optically selected starbursts have high AB (>0.3) compared to lower fractions in late (20% ) and early (12%). • K-S test on AB • - SB vs Early type : 1e-10 • - SB vs Late-type : 3e-4 AB Large AB : highly asymmetric distribution of massive SF (no m=2 symmetry) - Externally triggered : tidal interactions, mergers

  14. Q4: How Disk-Size Relation changes with environment and redshift ?

  15. Ravindranath et al. 2003 • Sersic indices n<2 • Rest-frame MB <-19.5 • Photometric redshifts

  16. Disk galaxy evolution from GOODSRavindranath et al. 2003 Number-densities are relatively constant to z~1 Tendency for smaller sizes at z~1 (30% smaller) after correcting for measurement bias

  17. Intermediate Redshift:Q5: How the Total SFRs Change with Redshift ?Q6: How the SFR for Different Types of Galaxies change with Redshift ?

  18. Rest-frame 2800 A:U: 0.30 < z < 0.42B: 0.52 < z < 0.68V: 0.88 < z < 1.04R: 1.13 < z < 1.37I: 1.62 < z < 1.87z: 2.11 < z < 2.33

  19. COSMOS-GOODS-GALEX

  20. Q7: What is the Effect of Environment on the SFR ?Q8: How the Environmental Effect Change with Redshift ?

  21. Median SFRs: 0.71 (F) 0.76 (C)0.30 < z < 0.42

  22. Median SFRs: 0.84 (F) 0.95 (C) 0.52 < z < 0.68

  23. Median SFRs: 2.45 (F) 2.75 (C)0.88 < z < 1.04

  24. SFR in Different Environments Field LSS Msun/yr 0.3 < z < 0.42 0.71 0.75 0.52 < z < 0.68 0.84 0.94 0.88 < z < 1.04 2.49 2.78

  25. Q9: What is the LF of Star-forming Galaxies ?Q10: How the LF for Star-forming Galaxies Change with Redshift ?Q11: What is the Type-dependence of the LF ?

  26. LF Parameters for a=-1.2 M*28000.30 < z < 0.42 -18.290.52 < z < 0.68 -18.96 0.88 < z < 1.04 –19.18 1.13 < z < 1.37 –19.311.62 < z < 1.87 –20.062.11 < z < 2.33 –20.38

  27. Type-dependent 2800 A LF parameters M*a (2800A) Total -18.96 -1.20 Early-type -19.19 -1.12 Late-Type -18.78 -0.95 Starburst -18.71 -1.55

  28. High-zQ12: What is the SFR and Stellar Mass Associated with LBGs and LAEs at 4.5 < z < 6.5 ?

  29. rest-optical & -IR at z=5.8 • SST IRAC detections of z~6 galaxies => stellar population & dust fitting possible ch1, 3.6mm lrest=5300A ch2, 4.5mm lrest=6600A Dickinson et al in prep

  30. LBG at z=5.83Bviz (ACS) JHK (ISAAC) IRAC

  31. LAE at z=5.7Bviz (ACS) JHK (ISAAC) IRAC

  32. LAE LBG z 5.7 (6.2) 5.8 E(B-V) 0.2 0.1 Age (Gyr) 0.005 1.0 (Gyr) 0.2 0.8 Metallicity 0.05 0.008 Mass (Msun/yr) 1 x 1010 2.4 x 1010 Log (Lbol) 11.9 11.3

  33. SF Working Group • What can we do with the available data now? • What data we need ? • What we plan to do with the up-coming data (ie Ha, Spitzer) ?

  34. The available data: UV, U-band, BVRiz, radio, phot-z’s, spectral types, mass, LSS identification, rest-frame 2800A Future useful data: Near-IR spectroscopy, sub-mm data Up-coming data: Ha, Spitzer

  35. SFR- Outstanding Questions: • How different star formation diagnostics are compared ? • What is the role of galaxy mergers on SF activity ? • How the SFR changes with redshift for different morphologies of galaxies ? • Are dusty galaxies more actively star forming ? • How SFR depends on galaxy environment ? • What is the relation between the mass of galaxies and their SFRs ? How does this depend on the environment/redshift/morphology ?

  36. Continued… • How the LF and correlation function of SF galaxies change with redshift/morphology ? • What regulates the SFR for LBGs and LAEs ? ( mass ? Size? Morphology?). How different are these in terms of their SF activity ? • Extension of SFR vs. redshift relation to z~7, using narrow-band and LBG surveys. • Type-dependence of the SFR vs. z relation • How different is the SFR in filamentary structures compared to clusters or isolated fields ? How does this change with morphology ?

  37. Continued… • Could the MIPS data be used to measure SFR (from PAH) at z~2 ? 82% of the SF galaxies in GOODS-N have MIPS detection. • How effectively we could use Paschen lines to measure dust-free SFR ? Would IRS be useful ? • Evolution of SFR-mass relation • Cross correlation between SFR and mass maps

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