COMPLETE INFRARED SPECTRAL ENERGY DISTRIBUTIONS OF MILLIMETER DETECTED QUASARS AT z > 5

• Published in: The Astrophysical journal Vol. 772; no. 2; pp. 1 - 15
• Main Authors: LEIPSKI, C, Meisenheimer, K, Walter, F, Besel, M-A, Dannerbauer, H, Fan, X, Haas, M, Klaas, U, Krause, O, Rix, H-W
• Format: Journal Article
• Language: English
• Published: United States 01.08.2013
• Subjects: ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BOLOMETERS; COSMIC DUST; COSMIC NUCLEI; EMISSION; ENERGY SPECTRA; FAR INFRARED RADIATION; LUMINOSITY; PHOTOMETRY; Pollution sources; QUASARS; RED SHIFT; Spectral energy distribution; Strength; WAVELENGTHS
• ISSN: 0004-637X; 1538-4357
• DOI: 10.1088/0004-637X/772/2/103

We present Herschel far-infrared (FIR) photometry of 11 quasars at redshift z > 5 that have previously been detected at 1.2 mm. We perform full spectral energy distribution (SED) fits over the wavelength range [lambda] sub(rest) ~ 0.1-400 mu m for those objects with good Herschel detections. These fits reveal the need for an additional FIR component besides the emission from a dusty active galactic nucleus (AGN)-powered torus. This additional FIR component has temperatures of T sub(FIR) ~ 40-60 K with luminosities of L sub(8-1000) mu m ~ 10 super(13) L sub([middot in circle]) (accounting for 25%-60% of the bolometric FIR luminosity). If the FIR dust emission is due to star formation it would suggest star formation rates in excess of 1000 solar masses per year. We show that at long wavelengths ([lambda] sub(rest) [gap] 50 mu m) the contribution of the AGN-powered torus emission is negligible. This explains how previous FIR studies of high-redshift quasars that relied on single-component fits to (ground-based) observations at [lambda] sub(obs) [gap] 350 mu m reached T sub(FIR) and L sub(FIR) values similar to our complete SED fits. Stacking the Herschel data of four individually undetected sources reveals a significant average signal in the PACS bands but not in SPIRE. The average SED of sources with individual Herschel detections shows a striking surplus in near- and mid-infrared (MIR) emission when compared to common AGN templates. The comparison between two average SEDs (sources with and without individual Herschel detections) matched in the UV/optical indicates that for these objects the strength of the MIR emission may correlate with the strength of the FIR emission.