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Durham University

Department of Physics

Staff profile

Publication details for Prof David Alexander

Kato, Y., Matsuda, Y., Smail, I., Swinbank, A.M., Hatsukade, B., Umehata, H., Tanaka, I., Saito, T., Iono, D., Tamura, Y., Kohno, K., Erb, D.K., Lehmer, B.D., Geach, J.E., Steidel, C.C., Alexander, D.M., Yamada, T. & Hayashino, T. (2016). Herschel protocluster survey: a search for dusty star-forming galaxies in protoclusters at z = 2–3. Monthly Notices of the Royal Astronomical Society 460(4): 3861-3872.

Author(s) from Durham


We present a Herschel/SPIRE survey of three protoclusters at z = 2 − 3 (2QZCluster, HS1700, SSA22). Based on the SPIRE colours (S350/S250 and S500/S350) of 250 μm sources, we selected high redshift dusty star-forming galaxies potentially associated with the protoclusters. In the 2QZCluster field, we found a 4σ overdensity of six SPIRE sources around 4.5′ (∼ 2.2 Mpc) from a density peak of Hα emitters at z = 2.2. In the HS1700 field, we found a 5σ overdensity of eight SPIRE sources around 2.1′ (∼ 1.0 Mpc) from a density peak of LBGs at z = 2.3. We did not find any significant overdensities in SSA22 field, but we found three 500 μm sources are concentrated 3′ (∼1.4 Mpc) east to the LAEs overdensity. If all the SPIRE sources in these three overdensities are associated with protoclusters, the inferred star-formation rate densities are 103 − 104 times higher than the average value at the same redshifts. This suggests that dusty star-formation activity could be very strongly enhanced in z ∼ 2 − 3 protoclusters. Further observations are needed to confirm the redshifts of the SPIRE sources and to investigate what processes enhance the dusty star-formation activity in z ∼ 2 − 3 protoclusters.