Suchergebnisse

During an intensive Hubble Space Telescope (HST) Cosmic Origins Spectrograph (COS) UV monitoring campaign of the Seyfert 1 galaxy NGC 5548 performed from 2014 February to July, the normally highly correlated far-UV continuum and broad emission-line variations decorrelated for ∼ 60–70 days, starting ∼ 75 days after the first HST/COS observation. Following this anomalous state, the flux and variability of the broad emission lines returned to a more normal state. This transient behavior, characterised by significant deficits in flux and equivalent width of the strong broad UV emission lines, is the first of its kind to be unambiguously identified in an active galactic nucleus reverberation mapping campaign. The largest corresponding emission-line flux deficits occurred for the high-ionization collisionally excited lines, C iv and Si iv(+O iv]), and also He ii(+O iii]), while the anomaly in Lyα was substantially smaller. This pattern of behavior indicates a depletion in the flux of photons with Eph > 54 eV, relative to those near 13.6 eV. We suggest two plausible mechanisms for the observed behavior: (i) temporary obscuration of the ionizing continuum incident upon BLR clouds by a moving veil of material lying between the inner accretion disk and inner BLR, perhaps resulting from an episodic ejection of material from the disk, or (ii) a temporary change in the intrinsic ionizing continuum spectral energy distribution resulting in a deficit of ionizing photons with energies > 54 eV, possibly due to a transient restructuring of the Comptonizing atmosphere above the disk. Current evidence appears to favor the latter explanation ; Support for HST program number GO-13330 was provided by NASA through a grant from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. M.M.F., G.D.R., B.M.P., C.J.G., and R.W.P. are grateful for the support of the National Science Foundation (NSF) through grant AST-1008882 to The Ohio State University. A.J.B. and L.P. have been supported by NSF grant AST-1412693. A.V.F. and W.-K.Z. are grateful for fi- nancial assistance from NSF grant AST-1211916, the TABASGO Foundation, and the Christopher R. Redlich Fund. M.C. Bentz gratefully acknowledges support through NSF CAREER grant AST-1253702 to Georgia State University. M.C. Bottorff acknowledges HHMI for support through an undergraduate science education grant to Southwestern University. K.D.D. is supported by an NSF Fellowship awarded under grant AST- 1302093. R.E. gratefully acknowledges support from NASA under awards NNX13AC26G, NNX13AC63G, and NNX13AE99G. J.M.G. gratefully acknowledges support from NASA under award NNH13CH61C. P.B.H. is supported by NSERC. K.D.H. acknowledges support from the UK Science and Technology Facilities Council through grant ST/J001651/1. M.I. acknowledges support from the Creative Initiative program, No. 2008- 0060544, of the National Research Foundation of Korea (NRFK) funded by the Korean government (MSIP). M.D.J. acknowledges NSF grant AST0618209. SRON is financially supported by NWO, the Netherlands Organization for Scientific Research. B.C.K. is partially supported by the UC Center for Galaxy Evolution. C.S.K. acknowledges the support of NSF grant AST-1009756. D.C.L. acknowledges support from NSF grants AST- 1009571 and AST-1210311. P.L. acknowledges support from Fondecyt grant #1120328. A.P. acknowledges support from an NSF graduate fellowship and a UCSB Dean's Fellowship. J.S.S. acknowledges CNPq, National Council for Scientific and Technological Development (Brazil) for partial support and The Ohio State University for warm hospitality. T.T. has been supported by NSF grant AST-1412315. T.T. and B.C.K. acknowledge support from the Packard Foundation in the form of a Packard Research Fellowship to T.T; also, T.T. thanks the American Academy in Rome and the Observatory of Monteporzio Catone for kind hospitality. The Dark Cosmology Centre is funded by the Danish National Research Foundation. M.V. gratefully acknowledges support from the Danish Council for Independent Research via grant no. DFF 4002-00275. J.-H.W. acknowledges support by the National Research Foundation of Korea (NRF) grant funded by the Korean government (No. 2010-0027910). This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA. ; Peer-reviewed ; Publisher version

We present geometric and dynamical modeling of the broad line region (BLR) for the multi-wavelength reverberation mapping campaign focused on NGC 5548 in 2014. The data set includes photometric and spectroscopic monitoring in the optical and ultraviolet, covering the H beta, Civ, and Ly alpha broad emission lines. We find an extended disk-like H beta BLR with a mixture of near-circular and outflowing gas trajectories, while the Civand Ly alpha BLRs are much less extended and resemble shell-like structures. There is clear radial structure in the BLR, with Civand Ly alpha emission arising at smaller radii than the H beta emission. Using the three lines, we make three independent black hole mass measurements, all of which are consistent. Combining these results gives a joint inference of log(10) (M-BH/M-circle dot) = 7.64(-0.18)(+0.21). We examine the effect of using the V band instead of the UV continuum light curve on the results and find a size difference that is consistent with the measured UV-optical time lag, but the other structural and kinematic parameters remain unchanged, suggesting that theVband is a suitable proxy for the ionizing continuum when exploring the BLR structure and kinematics. Finally, we compare the H beta results to similar models of data obtained in 2008 when the active galactic nucleus was at a lower luminosity state. We find that the size of the emitting region increased during this time period, but the geometry and black hole mass remained unchanged, which confirms that the BLR kinematics suitably gauge the gravitational field of the central black hole. ; National Aeronautics & Space Administration (NASA) AST-1908952 AST-1814440 Space Telescope Science Institute National Science Foundation (NSF) AST-1211916 Packard Foundation through a Packard Fellowship AST-1412315 AST-1907208 Space Telescope Science Institute 17-ATP17-0141 19-ATP19-0188 NRF grant HST-AR-15018 HST-AR-14556 Korean Government 2020R1A2C3011091 Independent Research Fund Denmark DFF 8021-00130 NASA ADAP grant 80NSSC19K1016 National Science Foundation (NSF) Eberly Research Fellowship from The Pennsylvania State University Eberly College of Science AST-1909297 Center for Exoplanets Pennsylvania State University Eberly College of Science Pennsylvania Space Grant Consortium TABASGO Foundation Christopher R. Redlich Fund Miller Institute for Basic Research in Science (U.C. Berkeley)