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The galaxy luminosity function & its evolution probed with Chandra

The galaxy luminosity function & its evolution probed with Chandra. Ioannis Georgantopoulos (NOA) Panayiotis Tzanavaris (NOA) Antonis Georgakakis (ICL). XLF importance : why probing X-rays ?. Unique probe of X-ray binaries and hot gas in normal galaxies:

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The galaxy luminosity function & its evolution probed with Chandra

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  1. The galaxy luminosity function & its evolution probed with Chandra Ioannis Georgantopoulos (NOA) Panayiotis Tzanavaris (NOA) Antonis Georgakakis (ICL)

  2. XLF importance: why probing X-rays ? • Unique probe of X-ray binaries and hot gas in normal galaxies: • Early-type: Hot ISM (1 keV) + LMXRB • Late type HMXRB+LMXRB

  3. XLF importance X-rays are a very good SFR indicator : almost linear Lx-Lir relation over 4 orders of magnitude Ranalli+03 , see also Grimm+03 Time lag between optical and x-ray emission ? • HMXB dominant: Lx ~ optical, IR • LMXB dominant: Lx ~ delay with optical, IR (eg Ghosh & White 01, Eracleous+06)

  4. The Chandra & XMM potential • CDF-N opened a new window in the study of galaxies giving the first X-ray selected galaxy samples z-median~0.3). (Hornschemeier+03) • XMM provided X-ray samples in the low-z Universe (z-median~0.1) (Georgakakis+04, Georgantopoulos+05, Georgakakis+06)

  5. Low-z LF Schechter φ(L) dL = φ* (L/L*)αexp (-L/L*) d (L/L*) or log-norm LF

  6. Previous work: Evolution • Pure Luminosity Evolution L ~ (1+z)k • Norman et al. 2004 k = 2.7 (all) • Using the logN-logS Georgakakis et al 2006 k = 2.7 (late), Georgakakis et al 2007 k~0 (early) • Ptak et al 2007 k = 2.3 (late), 1.6 (early)

  7. The Current work : sample • E-CDF-S • CDF-N • CDF-S • XBOOTES

  8. Normal galaxies: selection criteria • Source detected in the 0.5-2.0 keV band • log ( fX [0.5-2.0 keV]/fR ) ≤ -1 (from filter) • log LX ≤ 42 (cgs) • HR ≡ (H-S)/(H+S) ≤ 0 • object morphologically a galaxy H ≡ 2.0-8.0 keV; S ≡ 0.5-2.0 keV

  9. AGN contamination ? For the above criteria ~25% likely Lx-Lir relation CDF-N See Georgakakis et al. 2007

  10. LX - z • 207 sources to z ~ 1.4 • subsamples complementary

  11. Luminosity function:Total sample  0 < z < 0.2  0.2 < z < 0.6  0.6 < z < 1.4 Norman et al. (2004) z < 0.5 triangles z > 0.5crosses Kim et al (2006) z < 0.3 stars Curves: ML fit parameters PLE L~(1+z)k k=2.2, logL*~41

  12. Luminosity function by type • Separate Early and Late-type systems • Hyperz • 61 template SEDs from smoothly interpolated (Sullivan et al 2004) four galaxy types • Filters for different surveys • E = 0 → 25 105 systems • L = 25 → 60 99 systems • Then binned XLF as before

  13. Redshift distributions • Histogram: observed -- early at low z late at higher z • Curves: ML results + area --- similar

  14. Luminosity function: Late types 0 < z < 0.4 0.4 < z < 1.4 • Solid: ML fit • Dashed: Georgakakis et al. (2006)

  15. Luminosity function: Early types  0 < z < 0.4 • 0.4 < z < 1.4 No evolution ? Curves as before…

  16. Late-type: evolution • k=2.2, cf Ptak et al. Georgakakis et al 2006b • Hopkins (2004) radio-selected SF galaxies k = 2.7 • Late type systems dominated by HMXRB and therefore follow the star-formation

  17. Early-type: mild or no-evolution ? • Consistent with no evolution (0.5 +/-0.8) • In agreement with Georgakakis et al. • Ptak et al. again find mild evolution k~1.6(+1.1,-1.0) • Evolution rather different from the optical one

  18. Comparison with optical LF • Optical LF based on COMBO-17 and DEEP-2 Up to z~1 (Faber et al. 2005) Red galaxies four times more density at z=0 Blue galaxies have the same density Both red and blue galaxies less luminous at z=0 by a factor of 3. Only the blue galaxies have the same evolution in the optical and X-rays.

  19. XLF from convolution XLF from convolution Convolving the optical LF (Nakamura 2003) with the Lx/LB relation (Shapley et al.) following Georgantopoulos et al. 1999

  20. Number-counts distributions • Solid: all sources (CDF) • Dotted: galaxies • Dot-dash: extrapolation • Limits (left -> right): CDF-N 2, 3, 4 Ms XEUS 1 Ms

  21. XEUS 1Ms predictions • > 2 x 104 / square deg for flux > 4 x 10-18 (cgs) • log Lx ~ 41 detectable to z ~ 2 • Counts from galaxies will overtake AGN counts at fluxes > 5 x 10-18 (cgs)

  22. Summary One of the largest NG samples with very broad coverage of L – z space k (full) = 2.2 k (late) = 2.4 k (early) ~ 0 Late type systems evolve roughly in the same manner with the optical, rather in contrast to the early type ones. These LF could be used to constrain models of X-ray binary evolution

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