منابع مشابه
Quasar Continuum Fitting and Silicon Absorption
We present results on the evolution of Lyae absorption at low redshift, and the first systematic search for Si II absorption systems in the low redshift IGM. Our sample consists of 832 Lyca absorbers from 328 spectra of 204 QSOs taken from the Hubble Space Telescope archive. We develop a new, reproducible method of quasar continuum fitting, designed to quickly identify absorption lines and meas...
متن کاملDifferential Microlensing of the Continuum and Broad Emission Lines in the Most Anomalous Lensed Quasar
SDSS J0924+0219 is the most glaring example of a gravitational lens with anomalous flux ratios: optical broad-band photometry shows image D to be a factor of 12 fainter than expected from smooth lens models. We report spectroscopy showing that the anomaly is present in the broad emission line flux ratios as well. There are differences between the emission line and continuum flux ratios: the A/D...
متن کاملThe 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 کاملEstimating the continuum of quasars using the articial neural networks
A lot of absorption lines are in the bluewards of Lyα emission line of quasar which is well-known as Lyαforest. Most of absorption lines in this forest belong to the Lyα absorption of the neutral hydrogen in the inter-galactic medium (IGM). For high redshift quasars and in the continuum with low and medium resolution, there are no many regions without absorption, so that, the quasar continuum i...
متن کاملTwo Close–Separation Quasar–Quasar Pairs in the Large Bright Quasar Survey
We present photometric and spectroscopic observations of two close quasar– quasar pairs found in the Large Bright Quasar Survey (LBQS) (Hewett et al. 1995, AJ, 109, 1498). The two components of the 2153-2056 pair (z = 1.845, ∆θ = 7. 8, B = 17.9 and 21.3) have the same redshifts within the relatively large uncertainty, ∆vA−B = −1100±1500 km s, of the observations. The quasars are most likely spa...
متن کاملذخیره در منابع من
با ذخیره ی این منبع در منابع من، دسترسی به آن را برای استفاده های بعدی آسان تر کنید
ژورنال
عنوان ژورنال: Proceedings of the International Astronomical Union
سال: 2009
ISSN: 1743-9213,1743-9221
DOI: 10.1017/s1743921310005570