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

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

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

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

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

Popis výsledku anglicky

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.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2021

Kód důvěrnosti údajů

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

Název periodika

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

e-ISSN

1365-2966

Svazek periodika

500

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

GB - Spojené království Velké Británie a Severního Irska

Počet stran výsledku

13

Strana od-do

2063-2075

Kód UT WoS článku

000605983000042

EID výsledku v databázi Scopus

2-s2.0-85097485760