Abstract
Aims. To understand the nature of transient obscuring outflows in active galactic nuclei, we use simultaneous multiwavelength observations with XMM-Newton, NuSTAR, the Hubble Space Telescope (HST), and the Max Planck Gesellschaft/European Southern Observatory (ESO) 2.2 m telescope triggered by soft X-ray absorption detected by Swift. Methods. We obtained ultraviolet spectra on 2016-12-12 and 2016-12-21 using the Cosmic Origins Spectrograph (COS) on HST simultaneously with X-ray spectra obtained with XMM-Newton and NuSTAR. We modeled the ultraviolet spectra to measure the strength and variability of the absorption, and used photoionization models to obtain its physical characteristics. Results. We find new components of broad, blue-shifted absorption associated with Lyα, Nâ V, Siâ IV, and Câ IV in our COS spectra. The absorption extends from near-zero velocities in the rest-frame of the host galaxy to-6200 km s -1 . These features appear for the first time in NGC 3783 at the same time as heavy soft X-ray absorption seen in the XMM-Newton X-ray spectra. The X-ray absorption has a column density of ∼10 23 cm -2 , and it partially covers the X-ray continuum source. Combining the X-ray column densities with the UV spectral observations yields an ionization parameter for the obscuring gas of log ξ = 1.84 -0.2 +0.4 erg cm s -1 . Despite the high intensity of the UV continuum in NGC 3783, F(1470 Å) = 8â ×â 10 -14 erg cm -2 s -1 Å -1 >, the well known narrow UV absorption lines are deeper than in earlier observations in unobscured states, and low ionization states such as Câ III appear, indicating that the narrow-line gas is more distant from the nucleus and is being shadowed by the gas producing the obscuration. Despite the high continuum flux levels in our observations of NGC 3783, moderate velocities in the UV broad line profiles have substantially diminished. Conclusions.We suggest that a collapse of the broad line region has led to the outburst and triggered the obscuring event.
| Original language | English |
|---|---|
| Article number | A12 |
| Number of pages | 24 |
| Journal | Astronomy and Astrophysics |
| Volume | 621 |
| Early online date | 19 Dec 2018 |
| DOIs | |
| Publication status | E-pub ahead of print - 19 Dec 2018 |
Funding
1 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA e-mail: [email protected] 2 SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands 3 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands 4 Max-Planck-Institut für Extraterrestriche Physik, Gießenbachstraße, 85748 Garching, Germany 5 Institute of Astronomy, KU Leuven, Celestijnenlaan 200D bus 2401, 3001 Leuven, Belgium 6 Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA 7 Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel 8 Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy 9 Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK 10 INAF-IASF Bologna, Via Gobetti 101, 40129 Bologna, Italy 11 Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland 12 Department of Astronomy, University of Geneva, 16 Ch. d’Ecogia, 1290 Versoix, Switzerland 13 European Space Astronomy Centre, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain 14 Department of Astronomy, The Ohio State University, 140 West 18th Ave., Columbus, OH 43210, USA 15 Center for Cosmology & AstroParticle Physics, The Ohio State University, 191 West Woodruff Ave., Columbus, OH 43210, USA 16 Univ. Grenoble Alpes, CNRES, IPAG, 38000 Grenoble, France 17 INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate, LC, Italy 18 Institute of Astronomy, Madingley Road, CB3 0HA Cambridge, UK Acknowledgements. This work is based on observations obtained with the NASA/ESA HST, and obtained from the Hubble Legacy Archive. This work was supported by NASA through a grant for HST program number 14481 from the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Incorporated, under NASA contract NAS5-26555. We also used XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and the USA (NASA), the NuSTAR mission, a project led by the California Institute of Technology (Caltech), managed by the Jet Propulsion Laboratory (JPL) and funded by NASA, and data supplied by the UK Swift Science Data Centre at the University of Leicester. We thank the XMM-Newton, NuSTAR, and HST teams for scheduling our Target of Opportunity triggered observations. SRON is supported financially by NWO, the Netherlands Organization for Scientific Research. SB acknowledges financial support from the Italian Space Agency under grant ASI-INAF I/037/12/0, and n. 2017-14-H.O. EC is partially supported by the NWO-Vidi grant number 633.042.525. BDM acknowledges support from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement No. 665778 via the Polish National Science Center grant Polonez UMO-2016/21/P/ST9/04025. POP acknowledges support from the CNES and CNRS/PNHE. GP acknowledges support from the Bundesministerium für Wirtschaft und Technologie/Deutsches Zentrum für Luft-und Raumfahrt (BMWI/DLR, FKZ 50 OR 1604) and the Max Planck Society.
Keywords
- galaxies: active
- galaxies: individual: NGC 3783
- galaxies: Seyfert
- quasars: absorption lines
- quasars: emission lines
- ultraviolet: galaxies