AKARI near- and mid-infrared spectroscopy of APM 08279 5255 at z=3.91 - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




AKARI near- and mid-infrared spectroscopy of APM 08279 5255 at z=3.91 - Astrophysics > Cosmology and Nongalactic Astrophysics - Download this document for free, or read online. Document in PDF available to download.

Abstract: We present rest-frame optical-near-infrared spectra of the gravitationallylense d quasar APM 08279+5255 at $z=3.91$ that has been taken using theInfrared Camera IRC onboard the AKARI infrared satellite. The observedcontinuum consists of two components; a power-law component dominating opticalwavelengths which is the direct light from the central source and thermalemission dominating near-infrared wavelengths which is attributed to theemission from hot dust in the circumnuclear region. The thermal emission wellrepresents optically thick emission by hot dust at T ~ 1300K with tau2micron>2 and apparent mass, Mhot >10 M sun. Thus, our observations directly detectedthe optically thick region of hot dust in APM 08279+5255. HI recombinationlines of H alpha0.656micron, Pa alpha1.875micron, and Pa beta1.282micronare clearly detected at 3.2, 6.3, and 9.3 micron. Simulations with thephotoionization models suggest that APM 08279+5255 has BLRBroad Line Regionclouds characterized by log n {H} ~ 12- 14 for the gas density, log U ~ -2 --6$ for the ionization parameter, and EB-V ~ 0.3-0.6$for the broad lineregion. Thus, optically thick emission of hot dust support an idea onnon-spherical distribution of dust near the central source, consistent with theActive Galactic Nuclei model with the dust torus. The temperature of hot dustand flux ratios of these HI lines are similar to those observed in low-redshiftquasars. There are significant time-variations in the HI lines, which areprobably caused by variations in the brightness of the central source.



Author: S. Oyabu 1, K. Kawara 2, Y. Tsuzuki 3, Y. Matsuoka 2, H. Sameshima 2, N. Asami 2, Y. Ohyama 4 1Institute of Space and Astronautic

Source: https://arxiv.org/







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