The Hα luminosity function and star formation rate at z ≈ 0.24 in the COSMOS 2 square degree field

Y. Shioya, Y. Taniguchi, S. S. Sasaki, T. Nagao, T. Murayama, M. I. Takahashi, M. Ajiki, Y. Ideue, S. Mihara, A. Nakajima, N. Z. Scoville, B. Mobasher, H. Aussel, M. Giavalisco, L. Guzzo, G. Hasinger, C. Impey, O. L.E. Fèvre, S. Lilly, A. RenziniM. Rich, D. B. Sanders, E. Schinnerer, P. Shopbell, A. Leauthaud, J. P. Kneib, J. Rhodes, R. Massey

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70 Scopus citations


To derive a new Hα luminosity function and to understand the clustering properties of star-forming galaxies at z ≈ 0.24, we have made a narrowband imaging survey for Hα-emitting galaxies in the Hubble Space Telescope (HST) COSMOS 2 square degree field. We used the narrowband filter NB816 (λc = 8150 Å, Δλ = 120 Å) and sampled Hα emitters with EWobs( Hα+ [N II]) > 12 Å in a redshift range between z = 0.233 and 0.251 corresponding to a depth of 70 Mpc. We obtained 980 Hα-emitting galaxies in a sky area of 5540 arcmin2, corresponding to a survey volume of 3.1 × 10 4 Mpc3. We derive a Hα luminosity function with a best-fit Schechter function parameter set of α = -1.35 -0.13+0.11, log φ* = -2.65-0.38 +0.27 and log L*(ergs s-1) = 41.94 -0.23+0.38. The Hα luminosity density is 2.7 -0.6+0.7 × 1039 ergs s-1 Mpc-3. After subtracting the AGN contribution (15%) to the Hα luminosity density, the star formation rate density is evaluated as 1.8 -0.4+0.7 × 10-2 M yr-1 Mpc-3. The angular two-point correlation function of Hα-emitting galaxies of log L(Hα) > 39.8 is well fit by a power-law form of w(θ) = 0.013-0.001 +0.002θ-0.88±0.03, corresponding to the correlation function of ξ(r) = (r/1.9 Mpc)-1.88. We also find that the Hα emitters with higher Hα luminosity are more strongly clustered than those with lower luminosity.

Original languageEnglish (US)
Pages (from-to)128-137
Number of pages10
JournalAstrophysical Journal, Supplement Series
Issue number1
StatePublished - Mar 2008


  • Galaxies: distances and redshifts
  • Galaxies: evolution
  • Galaxies: luminosity function, mass function

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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  • H{alpha} emitting galaxies in COSMOS-2 field

    Shioya, Y. (Creator), Taniguchi, Y. (Creator), Sasaki, S. S. (Creator), Nagao, T. (Creator), Murayama, T. (Creator), Takahashi, M. I. (Creator), Ajiki, M. (Creator), Ideue, Y. (Creator), Mihara, S. (Creator), Nakajima, A. (Creator), Scoville, N. Z. (Creator), Mobasher, B. (Creator), Aussel, H. (Creator), Giavalisco, M. (Creator), Guzzo, L. (Creator), Hasinger, G. (Creator), Impey, C. D. (Creator), Fèvre, O. L. E. (Contributor), Lilly, S. (Creator), Renzini, A. (Creator), Rich, M. (Creator), Sanders, D. B. (Creator), Schinnerer, E. (Creator), Shopbell, P. (Creator), Leauthaud, A. (Creator), Kneib, J. (Creator), Rhodes, J. (Creator), Massey, R. (Creator), Guzzo, L. (Creator), Sanders, D. B. (Creator) & Schinnerer, E. (Creator), Centre de Donnees Strasbourg (CDS), 2009


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