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arXiv · 1512.00167

Identification of z~>2 Herschel 500 micron sources using color-deconfusion

X. W. Shu·D. Elbaz·N. Bourne·C. Schreiber·T. Wang·J. S. Dunlop·A. Fontana·R. Leiton·M. Pannella·K. Okumura·M. J. Michalowski·P. Santini·E. Merlin·F. Buitrago·V. A. Bruce·R. Amorin·M. Castellano·S. Derriere·A. Comastri·N. Cappelluti·J. X. Wang·H. C. Ferguson
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Abstract

We present a new method to search for candidate z~>2 Herschel 500μm sources in the GOODS-North field, using a S500μm/S24μm "color deconfusion" technique. Potential high-z sources are selected against low-redshift ones from their large 500μm to 24μm flux density ratios. By effectively reducing the contribution from low-redshift populations to the observed 500μm emission, we are able to identify counterparts to high-z 500μm sources whose 24μm 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 1.5x10^12-1.8x10^13 Lsun, corresponding to dust-obscured star formation rates (SFRs) of ~260-3100 Msun/yr for a Salpeter IMF. Comparison with previous SCUBA 850μm-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 10 of the sources at z~>4. We find that at a fixed luminosity, the dust temperature is ~5K cooler than that expected from the Td-LIR relation at z<1, though different temperature selection effects should be taken into account. The radio-detected subsample (excluding three strong AGN) follows the far-infrared/radio correlation at lower redshifts, and no evolution with redshift is observed out to z~5, suggesting that the far-infrared emission is star formation dominated. The contribution of the high-z Herschel 500μm sources to the cosmic SFR density is comparable to that of SMG populations at z~2.5 and at least 40% of the extinction-corrected UV samples at z~4 (abridged).

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X. W. Shu, D. Elbaz, N. Bourne, C. Schreiber, T. Wang, J. S. Dunlop, A. Fontana, R. Leiton, M. Pannella, K. Okumura, M. J. Michalowski, P. Santini, E. Merlin, F. Buitrago, V. A. Bruce, R. Amorin, M. Castellano, S. Derriere, A. Comastri, N. Cappelluti, J. X. Wang, H. C. Ferguson. 2015-12-01. Identification of z~>2 Herschel 500 micron sources using color-deconfusion. https://doi.org/10.3847/0067-0049%2F222%2F1%2F4

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