16 μm imaging around the Hubble deep field-north with the Spitzer IRS

We present a pilot study of 16 mu m imaging within the GOODS northern field. Observations were obtained using the peak-up imaging capability of the Spitzer IRS. We survey 35 arcmin(2) to an average 3 sigma depth of 0.075 mJy and detect 149 sources. The survey partially overlaps the area imaged at 15 mu m by the ISO, and we demonstrate that our photometry and galaxy number counts are consistent with its measurements. We infer the total infrared luminosity of 16 mu m detections using a comparison to local templates and find a wide range of L-IR, from similar to 10(9) to 10(12) L-circle dot. Approximately 1 5 of the detected sources have counterparts in the Chandra 2 Ms catalog, and we show that the hard-band (2-8 keV) detected sources are likely to have strong active galactic nucleus (AGN) contributions to the X-ray flux. The ultradeep sensitivity of Chandra implies that some X-ray detections may be purely starbursting objects. We examine the 16 to 24 mu m flux ratio and conclude that it shows evidence for the detection of redshifted polycyclic aromatic hydrocarbon (PAH) emission at z similar to 0.5 and z > 0.8.