MAMBO Observations at 240GHz of optically obscured Spitzer sources: source clumps and radio activity at high redshift

TL;DR

This study uses MAMBO observations at 240GHz to investigate optically obscured Spitzer sources at high redshift, revealing their complex nature involving both AGN and starburst activity within a potential protocluster environment.

Contribution

First MAMBO 240GHz observations of optically faint Spitzer sources at high redshift, identifying their mixed AGN and starburst characteristics and their association with large-scale filamentary structures.

Findings

Detected four out of five sources at 240GHz.

Sources show combined AGN and starburst contributions to luminosity.

Sources are aligned along a filament connected to an AGN.

Abstract

Optically very faint R>25.5 sources detected by the Spitzer Space Telescope at 24um represent a very interesting population at redshift z [1.5-3]. They exhibit strong clustering properties, implying that they are hosted by very massive halos, and their mid-IR emission could be powered by either dust-enshrouded star-formation and/or by an obscured AGN. We report observations carried out with the MAMBO array at the IRAM 30m antenna on Pico Veleta of a candidate protocluster with five optically obscured sources selected from the 24um Spitzer sample of the First Look Survey. Interestingly, these sources appear to lie on a high density filament aligned with the two radio jets of an AGN. Four out of five of the observed sources were detected. We combine these measurements with optical, infrared and radio observations to probe}the nature of the candidate protocluster members. Our preliminary conclusions can be summarized as follows: the Spectral Energy Distributions of all sources include both AGN and starburst contributions; the AGN contribution to the bolometric luminosities ranges between 14 and 26% of the total. Such a contribution is enough for the AGN to dominate the emission at 5.8, 8 and 24um, while the stellar component, inferred from SED fitting, prevails at 1.25mm and at lambda<4.5um. The present analysis suggests a coherent interplay at high-z between extended radio activity and the development of filamentary large-scale structures.