Broad He I 1.08-mu m absorption from the obscurer in the active galaxy NGC 5548

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F21%3A00550187" target="_blank" >RIV/67985815:_____/21:00550187 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.1093/mnras/staa3301" target="_blank" >https://doi.org/10.1093/mnras/staa3301</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1093/mnras/staa3301" target="_blank" >10.1093/mnras/staa3301</a>

Result language

angličtina

Original language name

Broad He I 1.08-mu m absorption from the obscurer in the active galaxy NGC 5548

Original language description

The nucleus of the active galaxy NGC 5548 was the target of two intensive spectroscopic monitoring campaigns at X-ray, ultraviolet (UV), and optical frequencies in 2013/2014. These campaigns detected the presence of a massive obscuration event. In 2016/2017, Landt et al. conducted a near-IR spectroscopic monitoring campaign on NGC 5548 and discovered He I 1.08-mu m absorption. Here, we decompose this absorption into its components and study its time variability. We attribute the narrow He I absorption lines to the warm absorber (WA) and, as for the newly appeared low-ionization WA lines in the UV, their presence is most likely due to a reduction in ionization parameter caused by the obscurer. The observed variability of the narrow He I absorption is consistent with what is expected for the WA. Most importantly, we also detect fast, broad He I absorption, which we attribute to the obscurer. This He I broad absorption, which is indicative of a high column density gas, is unsaturated and variable on time-scales of a few months. The observed variability of the obscurer is mainly due to changes in ionization, although density changes also play a role. We test the physical cycle model of Dehghanian et al. which proposes that helium recombination can account for how the obscurer influences the physics of the WA gas. Our results support their model, but also indicate that the reality might be more complex.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

—

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2021

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

e-ISSN

1365-2966

Volume of the periodical

500

Issue of the periodical within the volume

2

Country of publishing house

GB - UNITED KINGDOM

Number of pages

13

Pages from-to

2063-2075

UT code for WoS article

000605983000042

EID of the result in the Scopus database

2-s2.0-85097485760