Abstract
We present a new method to search for candidate z ≳ 2 Herschel 500 μm sources in the Great Observatories Origins Deep Survey-North field using a S500 μm/S24 μm "color deconfusion" technique. Potential high-z sources are selected against low-redshift ones from their large 500 to 24 μm flux density ratios. By effectively reducing the contribution from low-redshift populations to the observed 500 μm emission, we are able to identify counterparts to high-z 500 μm sources whose 24 μm fluxes are relatively faint. The recovery of known z ≳ 4 starbursts confirms the efficiency of this approach in selecting high-z Herschel sources. The resulting sample consists of 34 dusty star-forming galaxies at z ≳ 2. The inferred infrared luminosities are in the range 1.5 × 1012-1.8 × 1013 L⊙, corresponding to dust-obscured star formation rates (SFRs) of ∼260-3100 M⊙ yr-1 for a Salpeter initial mass function. Comparison with previous SCUBA 850 μm-selected galaxy samples shows that our method is more efficient at selecting high-z dusty galaxies, with a median redshift of z = 3.07 ± 0.83 and with 10 of the sources at z ≳ 4. We find that at a fixed luminosity, the dust temperature is ∼5 K cooler than that expected from the Td relation at z ≲ 1, though different temperature selection effects should be taken into account. The radio-detected subsample (excluding three strong active galactic nucleus) follows the far-infrared (far-IR)/radio correlation at lower redshifts, and no evolution with redshift is observed out to z ∼ 5, suggesting that the far-IR emission is star formation dominated. The contribution of the high-z Herschel 500 μm sources to the cosmic SFR density is comparable to that of (sub)millimeter galaxy populations at z ∼ 2.5 and at least 40% of the extinction-corrected UV samples at z ∼ 4. Further investigation into the nature of these high-z dusty galaxies will be crucial for our understanding of the star formation histories and the buildup of stellar mass at the earliest cosmic epochs.
Original language | English (US) |
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Article number | 4 |
Journal | Astrophysical Journal, Supplement Series |
Volume | 222 |
Issue number | 1 |
DOIs | |
State | Published - Jan 2016 |
Externally published | Yes |
Keywords
- galaxies: high-redshift
- galaxies: starburst
- infrared: galaxies
- submillimeter: galaxies
ASJC Scopus subject areas
- Astronomy and Astrophysics
- Space and Planetary Science