English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Tools annual

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools monthly

Global: Zendy Plus monthly

Presents the access of premium content as premium feature

Premium Content

Global: Zendy Plus annual

Global: Zendy Free Plan

A previous narrow-slit ($0.1$ arcsec) Hubble Space Telescope observationunveiled a broad relativistic H$\alpha$ profile in NGC3147, a low-luminosity($\mathrm{L_{bol}}\sim10^{42}$ erg s$^{-1}$), low-Eddington ratio($\mathrm{L_{bol}/L_{Edd}}\sim10^{-4}$) active galactic nucleus (AGN), formerlybelieved to be a candidate true type 2 AGN intrinsically lacking the broad-lineregion. The new observations presented here confirm the double-peaked profileof the H$\alpha$ line, which further shows variability both in flux and in theinner radius of the emitting disc with respect to the previous epoch. Similardisc line profiles are also found in prominent ultraviolet (UV) lines, inparticular Ly$\alpha$ and C IV. The new data also allow us to build asimultaneous subarcsec optical-to-X-ray spectral energy distribution ofNGC3147, which is characterized by the absence of a thermal UV bump, and anemission peak in the X-rays. The resulting very flat $\alpha_{ox}=-0.82$ istypical of low-luminosity AGN, and is in good agreement with the extrapolationto low luminosities of the well-known trend with luminosity observed instandard AGN. Indeed, we are possibly observing the accretion disc emission inNGC3147 in the optical, close to the expected peak. On the other hand, thesteep -2 UV power law may be Comptonization of that cold disc by a warm corona,what is instead generally observed as a `soft excess' in more luminous AGN.

NGC 3147: a prototypical low-luminosity active galactic nucleus with double-peaked optical and ultraviolet lines