Hα emitting galaxies and the star formation rate density at z ≃ 0.24



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Pascual, S. and Gallego Maestro, Jesús and Aragón Salamanca, A. and Zamorano Calvo, Jaime (2001) Hα emitting galaxies and the star formation rate density at z ≃ 0.24. Astronomy and astrophysics, 379 (3). pp. 798-806. ISSN 0004-6361

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Official URL: http://dx.doi.org/10.1051/0004-6361:20011389


We have carried out a survey searching for Hα emitting galaxies at z ≃ 0.24 using a narrow band filter tuned with the redshifted line. The total sky area covered was 0.19 square degrees within the redshift range 0.228 to 0.255 in a set of four fields in the ELAIS-N1 zone. This corresponds to a volume of 9.8 x 10^3 Mpc^3 and a look-back time of 3.6 Gyr when H_0 = 50 km s^-1 Mpc^-1 and q_0 = 0.5 are assumed. A total of 52 objects are selected as candidates for a broad band limiting magnitude of I ~ 22.9, plus 16 detected only in the narrow band image for a narrow band limiting magnitude for object detection of 21.0. The threshold detection corresponds to about 20 Å equivalent width with an uncertainty of ~± 10 Å. Point-like objects (15) were excluded from our analysis using CLASS STAR parameter from SExtractor. The contamination from other emission lines such as [O II] λ 3727, H _ β and [O III] λ λ 4959, 5007 at redshifts 1.2, 0.66 and 0.61 respectively is estimated, and found to be negligible at the flux limits of our sample. We find an extinction-corrected H_ α luminosity density of (5.4 ± 1.1) x 10^39 erg s^-1 Mpc^-3. This uncertainty takes into account the photometric and Poissonian errors only. Assuming a constant relation between the H_α luminosity and star formation rate, the SFR density in the covered volume is (0.043 ± 0.009) M_⨀ yr^-1 Mpc^-3. This translates to (0.037 ± 0.009) M¬_⨀ yr^-1 Mpc^-3 when the total density is corrected for the AGN contribution as estimated in the local Universe. This value is a factor ~4 higher than the local SFR density. This result needs to be confirmed by future spectroscopic follow-up observations.

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© ESO 2001.
This paper is based on observations obtained at the German-Spanish Astronomical Centre, Calar Alto, Spain, operated by the Max-Planck-Institut fur Astronomie (MPIE), Heidelberg, jointly with the Spanish Commission for Astronomy. This research was supported by the Spanish Programa Nacional de Astronomía y Astrofísica under grant AYA2000-1790. S. Pascual acknowledges the receipt of a Formación de Profesorado Universitario fellowship from the Universidad Complutense de Madrid. A. Aragón Salamanca acknowledges generous financial support form the Royal Society. This work has benefitted from fruitful discussions with C. E. García Dabó and P. G. Pérez González.

Uncontrolled Keywords:Autofib redshift survey; Hubble deep field; Area iso survey; Luminosity function; Hierarchical universe; Emission; Evolution
Subjects:Sciences > Physics > Astrophysics
Sciences > Physics > Astronomy
ID Code:34317
Deposited On:18 Nov 2015 14:20
Last Modified:10 Dec 2018 15:05

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