The Dusty Young Universe - Star formation in high-redshift Quasars
Zusammenfassung der Projektergebnisse
High-redshift quasars are powerful probes for the early evolution of black holes and their host galaxies. Over the last decade and a half, various studies have revealed that even less than a billion years after the big bang, these objects are surprisingly similar to their low-redshift cousins. However, comprehensive studies of the infrared dust SED in z > 5 QSOs, including the diagnostically important and AGN dominated rest frame mid-infrared (MIR), had been missing. Within the framework of a dedicated project we studied for the first time the SEDs of 69 QSOs at redshift z > 5, covering rest frame wavelengths from 0.1 to ∼80 µm. For this purpose we obtained an unprecedented suite of infrared observations using the Herschel and Spitzer Space Observatories. This allowed us to show that emission of hot dust observed in the rest frame near-infared is ubiquitous in quasars across the observable universe. While our detection rate steadily decreases towards the (observed) far infrared, many of the brightest (in the UV/optical) quasars are dominated by powerful emission from AGN-heated dust in the infrared. In a handful of objects, strong excess in the far infrared signifies copious star formation activity in the growing host galaxies of the early quasars. The investigation of stacked SEDs reveals a trend where quasars with lower UV/optical luminosity show on average reduced importance of the AGN-heated dust in their SEDs relative to their accretion luminosity when compared to the most optically luminous quasars in our sample (including a potentially stronger emphasis on hotter dust, i.e., higher NIR-to-MIR luminosity ratios). The results of this study offer a unique insight into the infrared properties of high-redshift quasars and the Herschel and Spitzer observations will be of important legacy value for many years.
Projektbezogene Publikationen (Auswahl)
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”The dust emission of high-redshift quasars”, 2012, Journal of Physics Conference Series, 372, 2037
C. Leipski & K. Meisenheimer
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”Complete Infrared Spectral Energy Distributions of Millimeter Detected Quasars at z > 5”, 2013, Astrophysical Journal, 744, 152
Leipski, C.; Meisenheimer, K.; Walter, F.; Besel, M.-A.; Dannerbauer, H.; Fan, X.; Haas, M.; Klaas, U.; Krause, O. & Rix, H.-W.
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”Spectral Energy Distributions of QSOs at z > 5: Common Active Galactic Nucleus-heated Dust and Occasionally Strong Star-formation”, 2014, Astrophysical Journal, 772, 103
Leipski, C.; Meisenheimer, K.; Walter, F.; Klaas, U.; Dannerbauer, H.; De Rosa, G.; Fan, X.; Haas, M.; Krause, O. & Rix, H.-W.
