Dust and the Far-uv Spectral Energy Distribution of Quasars
نویسندگان
چکیده
The spectral energy distribution of quasars shows a sharp steepening of the continuum shortward of ≃ 1100 Å. We present a new dust extinction model consisting of crystalline carbon grains. We analyze the unusual extinction properties of this dust and proceed to show how the observed UV spectral break can be successfully modelled by crystalline carbon dust.
منابع مشابه
The unusual UV continuum of quasar Ton 34 and the possibility of crystalline dust absorption
Context. Luminous quasars are known to display a sharp steepening of the continuum near 1100 Å. This spectral feature is not well fitted by current accretion disk models, unless comptonization of the disk emission is invoked. Absorption by carbon crystalline dust has been proposed to account for this feature. Aims. Ton 34 (zq = 1.928) exhibits the steepest far-UV decline (Fν ∝ ν ) among the 183...
متن کاملThe far-infrared emission of radio loud and radio quiet quasars
Continuum observations at radio, millimetre, infrared and soft X-ray energies are presented for a sample of 22 quasars, consisting of flat and steep spectrum radio loud, radio intermediate and radio quiet objects. The primary observational distinctions, among the different kinds of quasars in the radio and IR energy domains are studied using large observational datasets provided by ISOPHOT on b...
متن کاملISO continuum observations of quasars at z = 1 - 4 ⋆ I . Spectral energy distributions of quasars from the UV to far - infrared
Eight luminous quasars with −30 < MB < −27 at z = 1.4 3.7 have been observed in the midand far-infrared using ISO. All the quasars have been detected in the mid-infrared bands of ISOCAM, while no far-infrared detections have been made with ISOPHOT. SEDs (Spectral Energy Distributions) from the UV to far-infrared have been obtained while supplementing ISO observations with photometry in the opti...
متن کاملMicron Dust Emission from High Redshift Quasars
We report detections of six high-redshift (1.8 ≤ z ≤ 6.4), optically luminous, radio-quiet quasars at 350 μm, using the SHARC II bolometer camera at the Caltech Submillimeter Observatory. Our observations double the number of high-redshift quasars for which 350 μm photometry is available. By combining the 350 μm measurements with observations at other submillimeter/millimeter wavelengths, for e...
متن کاملThe far-infrared–submm spectral energy distribution of high-redshift quasars
We combine photometric observations of high-redshift (z > 4) quasars, obtained at submillimetre (submm) to millimetre wavelengths, to obtain a mean far-infrared (FIR) (rest-frame) spectral energy distribution (SED) of the thermal emission from dust, parameterised by a single temperature (T ) and power-law emissivity index (β). Bestfit values are T = 41 ± 5K, β = 1.95± 0.3. Our method exploits t...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
عنوان ژورنال:
دوره شماره
صفحات -
تاریخ انتشار 2005