HST unveils a compact mildly relativistic Broad Line Region in the candidate true type 2 NGC 3147

Abstract

NGC 3147 has been considered the best case of a true type 2 AGN: an unobscured AGN, based on the unabsorbed compact X-ray continuum, which lacks a broad line region (BLR). However, the very low luminosity of NGC 3147 implies a compact BLR, which produces very broad lines, hard to detect against the dominant background host galaxy. Narrow (0.1"x0.1") slit HST spectroscopy allowed us to exclude most of the host galaxy light, and revealed an H$\alpha$ line with an extremely broad base (FWZI$\sim 27000$ km s${}^{-1}$). The line profile shows a steep cutoff blue wing and an extended red wing, which match the signature of a mildly relativistic thin accretion disk line profile. It is indeed well fit with a nearly face on thin disk, at $i\sim 23^{\circ }$, with an inner radius at $77\pm 15$ r${}_g$, which matches the prediction of $62_{-14}^{+18}$ r${}_g$ from the $R_{\mathrm{BLR}}\sim L^{1/2}$ relation. This result questions the very existence of true type 2 AGN. Moreover, the detection of a thin disk, which extends below 100 r${}_g$ in an $L/L_{\mathrm{Edd}}\sim 10^{-4}$ system, contradicts the current view of the accretion flow configuration at extremely low accretion rates.

arXiv comment6 pages, 3 figures, accepted for publication in MNRAS Letters

References in corpus (44)

• The M-sigma and M-L Relations in Galactic Bulges and Determinations of their Intrinsic Scatter
• On the Fate of Gas Accreting at a Low Rate onto a Black Hole
• Revisiting the Unified Model of Active Galactic Nuclei
• The Low-Luminosity End of the Radius-Luminosity Relationship for Active Galactic Nuclei
• Estimating Black Hole Masses in Active Galaxies Using the Halpha Emission Line
• Constraining Black Hole Spin Via X-ray Spectroscopy
• Dynamics of Line-Driven Disk Winds in Active Galactic Nuclei II: Effects of Disk Radiation
• The AGN Obscuring Torus -- End of the "Doughnut" Paradigm?
• Reverberation Mapping of High-Luminosity Quasars: First Results
• The origin of the Broad Line Region in Active Galactic Nuclei
• Completion of a Survey and Detailed Study of Double-Peaked Emission Lines in Radio-Loud AGNs
• Double-Peaked Low-Ionization Emission Lines in Active Galactic Nuclei
• Broad Emission Line Regions in AGN: the Link with the Accretion Power
• An Empirical Pixel-Based Correction for Imperfect CTE. I. HST's Advanced Camera for Surveys
• On the Disappearance of the Broad-Line Region in Low-Luminosity Agns
• Hidden Broad Line Seyfert 2 Galaxies in the CfA and 12micron Samples
• Unabsorbed Seyfert 2 galaxies
• GHASP : An Halpha kinematic survey of spiral and irregular galaxies - VI. New Halpha data cubes for 108 galaxies
• The Unified Model & Evolution of Active Galaxies: Implications from a Spectropolarimetric Study
• Dust inflated accretion disc as the origin of the Broad Line Region in Active Galactic Nuclei
• Type 1 low z AGN. I. Emission properties
• Double-Peaked Broad Emission Lines in NGC 4450 and Other LINERs
• On The Nature of Low Luminosity Narrow Line AGN
• Double-peaked profiles: ubiquitous signatures of disks in the Broad Emission Lines of Active Galactic Nuclei
• Type 1 AGN at low z. II. The relative strength of narrow lines and the nature of intermediate type AGN
• The Link Between the Hidden Broad Line Region and the Accretion Rate in Seyfert 2 Galaxies
• Hunting for Supermassive Black Holes in Nearby Galaxies with the Hobby-Eberly Telescope
• The INTEGRAL/IBIS AGN catalogue I: X-ray absorption properties versus optical classification
• Unobscured Type 2 AGNs
• Evidence for a Black Hole and Accretion Disk in the LINER NGC 4203
• The Broad-Line and Narrow-Line Regions of the LINER NGC 4579
• Indecent Exposure in Seyfert 2 Galaxies: A Close Look
• Simultaneous X-ray and optical observations of true Type 2 Seyfert galaxies
• NGC3147: a "true" Seyfert 2 without the broad-line region
• The Unified model and the Seyfert 2 infrared dichotomy
• Unabsorbed Seyfert 2 galaxies: the case of "naked" AGN
• Naked active galactic nuclei
• Upholding the Unified Model for Active Galactic Nuclei: VLT/FORS2 Spectropolarimetry of Seyfert 2 galaxies
• The HST view of the broad line region in low luminosity AGN
• Two extreme double-peaked line emitters in the Sloan Digital Sky Survey
• Nuclear obscuration and scattering in Seyfert 2 galaxies
• Hidden Double-Peaked Emitters in Seyfert 2 Galaxies
• The Suzaku X-ray spectrum of NGC 3147. Further insights on the best "true" Seyfert 2 galaxy candidate
• The NuSTAR view of the true Type 2 Seyfert NGC3147

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