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arXiv · 2402.10444

Quasar winds caught on acceleration and deceleration

Weimin Yi·P. B. Hall·Zunlin Yuan·W. N. Brandt·D. P. Schneider·Zhicheng He·Jin-Ming Bai·Xue-Bing Wu
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Abstract

We present an observational study of wind acceleration based on four low-ionization broad absorption line (LoBAL) quasars (J0136, J1238, J1259, J1344). J0136 and J1344 (group-1) are radio quiet and show large BAL-velocity shifts as opposed to stable line-locking associated absorption lines (AALs). Notably, J1344 displays a linear relation between BAL-velocity shift and time interval over three consecutive epochs, characteristic of compelling evidence for BAL acceleration. J1238 and J1259 (group 2) exhibit small BAL-velocity shifts along with steep-spectrum, weak radio emission at 3.0 and 1.4 GHz. All four quasars have spectral energy distributions (SEDs) with a peak at $\lambda_{\rm rest }\sim10~\mu$m, suggesting a link between the BAL acceleration and hot dust emission. The group-2 quasars are redder than group-1 quasars and have a steeper rise at $1<\lambda_{\rm rest }<3~\mu$m in their SEDs. All but J1238 exhibit a steep rise followed by a plateau-like time evolution in BAL-velocity shift. Our investigations, combined with previous studies of BAL acceleration, indicate that (1) the BAL-ISM coupling process is one of the major avenues for the origin of quasar reddening and patchy obscuration, (2) AAL outflows are ubiquitous and likely signify large-scale remnants of BAL winds coupled to interstellar medium (ISM), and (3) wind deceleration that is closely linked to the BAL-ISM coupling process may produce weak radio emission in otherwise radio-quiet quasars.

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Weimin Yi, P. B. Hall, Zunlin Yuan, W. N. Brandt, D. P. Schneider, Zhicheng He, Jin-Ming Bai, Xue-Bing Wu. 2024-02-16. Quasar winds caught on acceleration and deceleration. https://arxiv.org/abs/2402.10444

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