On the emergence of THOUSANDS of absorption lines in the quasar PG 1411+442: a clumpy high-column density outflow from the broad emission-line region?
Tripp, Todd M.; Hamann, Fred; Veilleux, Sylvain; Rupke, David
United States, United Kingdom
Abstract
Quasar outflows are fundamental components of quasar environments that might play an important role in feedback to galaxy evolution. We report on the emergence of a remarkable new outflow absorption-line system in the quasar PG1411+442 (redshift ∼0.089) detected in the UV and visible with the Hubble Space Telescope Cosmic Origins Spectrograph and the Gemini Multi-Object Spectrograph, respectively. This new `transient' system contains thousands of lines, including Fe II and Fe II∗ from excited states up to 3.89 eV, H I∗ Balmer lines, Na I D λλ5890, 5896, and the first detection of He I∗ λ5876 in a quasar. The transient absorber is spatially inhomogeneous and compact, with sizes ≲0.003 pc, based on covering fractions on the quasar continuum source ranging from ∼0.45 in strong UV lines to ∼0.04 in Na I D. CLOUDY photoionization simulations show that large total column densities log NH(cm-2) ≳ 23.4 and an intense radiation field ≲0.4 pc from the quasar are needed to produce the observed lines in thick zones of both fully ionized and partially ionized gas. The densities are conservatively log nH(cm-3) ≳ 7 based on Fe II∗, H I∗, and He I∗ but they might reach log nH(cm-3) ≳ 10 based on Na I D. The transient lines appear at roughly the same velocity shift, v ∼ -1900 km s-1, as a `mini-BAL' outflow detected previously, but with narrower Doppler widths, b ∼ 100 km s-1, and larger column densities in more compact outflow structures. We propose that the transient lines identify a clumpy outflow from the broad emission-line region that, at its current speed and location, is still gravitationally bound to the central black hole.