Submillimetre Constraints on Hyper-Extremely Red Objects in the Subaru Deep Field

Abstract

We have mapped the submillimetre wavelength continuum emission from the Subaru Deep Field (SDF) at 450 and 850 microns with the Submillimetre Common-User Bolometer Array (SCUBA) detector on the James Clerk Maxwell Telescope (JCMT). The near-IR image of the SDF is one of the deepest near-IR images available and contains four `hyper extremely red objects' (HEROs). These data allow us to test the connection between `extremely red objects' (EROs) found in IR surveys and the population of bright submillimetre sources found with SCUBA. We present a weak measurement of the average flux of the four K-band selected HEROs of 1.15 (+/-0.46) mJy, which fails to support the hypothesis that HEROs should be bright SCUBA sources. Our data are consistent with the HEROs being objects with SEDs like that of Arp220 out to z~1.7, however, the extinction in the HEROs must be about 1 magnitude greater in the J-band than is the case for Arp220 and they would need to be 1.7 times as luminous as Arp220. On the other hand, an evolutionary model of elliptical galaxies at z~2-3 in a dusty starburst phase is also in agreement with the submillimetre data, as was originally proposed for the HEROs.Comment: 7 pages, 5 figures, accepted for publication in MNRAS July 5th, 200