We have observed 104 gravitationally lensed quasars at z ∼ 1-4 with Herschel/SPIRE, the largest such sample ever studied. By targeting gravitational lenses, we probe intrinsic far-infrared (FIR) luminosities and star formation rates (SFRs) more typical of the population than the extremely luminous sources that are otherwise accessible. We detect 72 objects with Herschel/SPIRE and find 66 per cent (69 sources) of the sample have spectral energy distributions (SEDs) characteristic of dust emission. For 53 objects with sufficiently constrained SEDs, we find a median effective dust temperature of 38^{+12}_{-5} K. By applying the radio-infrared correlation, we find no evidence for an FIR excess that is consistent with star-formation-heated dust. We derive a median magnification-corrected FIR luminosity of 3.6^{+4.8}_{-2.4} × 10^{11} L_{⊙} and median SFR of 120^{+160}_{-80} M_{⊙} yr^{-1}} for 94 quasars with redshifts. We find ∼10 per cent of our sample have FIR properties similar to typical dusty star-forming galaxies at z ∼ 2-3 and a range of SFRs <20-10 000 M⊙ yr-1 for our sample as a whole. These results are in line with current models of quasar evolution and suggests a coexistence of dust-obscured star formation and AGN activity is typical of most quasars. We do not find a statistically significant difference in the FIR luminosities of quasars in our sample with a radio excess relative to the radio-infrared correlation. Synchrotron emission is found to dominate at FIR wavelengths for <15 per cent of those sources classified as powerful radio galaxies.
{Gravitational lensing reveals extreme dust-obscured star formation in quasar host galaxies} / Stacey, H. ~r.; Mckean, J. ~p.; Robertson, N. ~c.; Ivison, R. ~j.; Isaak, K. ~g.; Schleicher, Dominik Reinhold Georg; Van Der Werf, P. ~p.; Baan, W. ~a.; Berciano Alba, A.; Garrett, M. ~a.; Loenen, E.. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 1365-2966. - (2018).
{Gravitational lensing reveals extreme dust-obscured star formation in quasar host galaxies}
Schleicher, Dominik Reinhold Georg;
2018
Abstract
We have observed 104 gravitationally lensed quasars at z ∼ 1-4 with Herschel/SPIRE, the largest such sample ever studied. By targeting gravitational lenses, we probe intrinsic far-infrared (FIR) luminosities and star formation rates (SFRs) more typical of the population than the extremely luminous sources that are otherwise accessible. We detect 72 objects with Herschel/SPIRE and find 66 per cent (69 sources) of the sample have spectral energy distributions (SEDs) characteristic of dust emission. For 53 objects with sufficiently constrained SEDs, we find a median effective dust temperature of 38^{+12}_{-5} K. By applying the radio-infrared correlation, we find no evidence for an FIR excess that is consistent with star-formation-heated dust. We derive a median magnification-corrected FIR luminosity of 3.6^{+4.8}_{-2.4} × 10^{11} L_{⊙} and median SFR of 120^{+160}_{-80} M_{⊙} yr^{-1}} for 94 quasars with redshifts. We find ∼10 per cent of our sample have FIR properties similar to typical dusty star-forming galaxies at z ∼ 2-3 and a range of SFRs <20-10 000 M⊙ yr-1 for our sample as a whole. These results are in line with current models of quasar evolution and suggests a coexistence of dust-obscured star formation and AGN activity is typical of most quasars. We do not find a statistically significant difference in the FIR luminosities of quasars in our sample with a radio excess relative to the radio-infrared correlation. Synchrotron emission is found to dominate at FIR wavelengths for <15 per cent of those sources classified as powerful radio galaxies.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
