The missing UV absorption lines of NGC 4151
نویسندگان
چکیده
منابع مشابه
OSSE Observations of NGC 4151
We report results of a two-week observation of the Seyfert galaxy NGC 4151 with the Oriented Scintillation Spectrometer Experiment (OSSE) instrument on the Compton Gamma Ray Observatory (GRO). The source had a very soft spectrum which is best represented by a broken power law or Sunyaev-Titarchuk thermal Comptonization model. It can be characterized by an exponential shape with an e-folding ene...
متن کاملThe origin of the correlation between the UV and X - rays in NGC 4151
We propose that the UV/X-ray correlation observed in NGC 4151 by EXOSAT and IUE is due to reemission of the X-ray flux absorbed by cold clouds in the line of sight. This transmission model satisfies the energy balance, provides a good fit to the X-ray and UV data, and predicts no Compton reflection of X-rays (as observed). The correlation can alternatively be explained by reprocessing of X-rays...
متن کاملEchelle Observations of NGC 4151 : Variable Ionization of the Intrinsic UV Absorbers
We present echelle observations of the intrinsic UV absorption lines in the Seyfert galaxy NGC 4151, which were obtained with the Space Telescope Imaging Spectrograph (STIS) on the Hubble Space Telescope (HST) on 1999 July 19. The UV continuum flux at 1450Å decreased by factor of about four over the previous two years and there was a corresponding dramatic increase in the column densities of th...
متن کاملFar-uv Observations of Ngc 4151 during the Orfeus-spas Ii Mission
We observed the Seyfert 1 galaxy NGC 4151 on eleven occasions at 1–2 day intervals using the Berkeley spectrometer during the ORFEUS-SPAS II mission in 1996 November. The mean spectrum covers 912–1220 A at ∼0.3 A resolution with a total exposure of 15,658 seconds. The mean flux at 1000 A was 4.7×10−13 erg cm−2 s−1 A−1. We identify the neutral hydrogen absorption with a number of components that...
متن کاملCharacterising the complex absorber in NGC 4151
We present a detailed analysis of the complex absorption apparent in the 2–6 keV X-ray spectrum of the bright nearby Seyfert galaxy NGC 4151. We first utilize the large bandpass and medium spectral resolution afforded by BeppoSAX data to construct a 1–100 keV spectral template, which assumes the absorption arises in both warm (i.e. partially photoionized) and cold gas present in the line of sig...
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ژورنال
عنوان ژورنال: Monthly Notices of the Royal Astronomical Society
سال: 1991
ISSN: 0035-8711,1365-2966
DOI: 10.1093/mnras/249.1.24p