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The H-alpha luminosity function at redshift 2.2 A new determination using VLT/HAWK-I
Stockholm University, Faculty of Science, Department of Astronomy.
2010 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 509, no L5Article in journal (Refereed) Published
Abstract [en]

We aim to place new, strengthened constraints on the luminosity function (LF) of H-alpha (H alpha) emitting galaxies at redshift z approximate to 2.2, and to further constrain the instantaneous star-formation rate density of the universe ((rho) over dot(star)). We have used the new HAWK-I instrument at ESO-VLT to obtain extremely deep narrow-band (line; NB2090) and broad-band (continuum; K-s) imaging observations. The target field is in the GOODS-South, providing us with a rich multi-wavelength auxiliary data set, which we utilise for redshift confirmation and to estimate dust content. We use this new data to measure the faint-end slope (alpha) of LF(H alpha) with unprecedented precision. The data are well fit by a Schechter function and also a single power-law, yielding alpha = (-1.72 +/- 0.20) and (-1.77 +/- 0.21), respectively. Thus we are able to confirm the steepening of a from low-to high-z predicted by a number of authors and observed at other wavelengths. We combine our LF data-points with those from a much shallower but wider survey at z similar to 2.2 (Geach et al. 2008), constructing a LF spanning a factor of 50 in luminosity. Re-fitting the Schechter parameters, we obtain log L-star = (43.07 +/- 0.22) erg s(-1); log phi(star) = (-3.45 +/- 0.52) Mpc(-3); alpha = (-1.60 +/- 0.15). We integrate over LF(H alpha) and apply a correction for dust attenuation to determine the instantaneous cosmic star-formation rate density at z similar to 2 without assuming alpha or extrapolating it from lower-z. Our measurement of (rho) over dot(star) is (0.215 +/- 0.090) M-circle dot yr(-1) Mpc(-3), integrated over a range of 37 <= log(L-H alpha/erg s(-1)) <= 47.

Place, publisher, year, edition, pages
2010. Vol. 509, no L5
Keyword [en]
galaxies: fundamental parameters, galaxies: high-redshift, galaxies: evolution, galaxies: starburst, galaxies: luminosity function, mass function
National Category
Astronomy, Astrophysics and Cosmology
URN: urn:nbn:se:su:diva-50168DOI: 10.1051/0004-6361/200913217ISI: 000274159400006OAI: diva2:381942
authorCount :3Available from: 2010-12-29 Created: 2010-12-21 Last updated: 2010-12-29Bibliographically approved

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Östlin, Göran
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