X-ray spectral variability of low ionization nuclear emission line regions (LINERs)

Hernández-García, L.; González-Martín, O.; Masegosa, J.; Márquez, I.
Referencia bibliográfica

Highlights of Spanish Astrophysics VIII, Proceedings of the XI Scientific Meeting of the Spanish Astronomical Society held on September 8-12, 2014, in Teruel, Spain, ISBN 978-84-606-8760-3. A. J. Cenarro, F. Figueras, C. Hernández-Monteagudo, J. Trujillo Bueno, and L. Valdivielso (eds.), p. 228-233

Fecha de publicación:
5
2015
Número de autores
4
Número de autores del IAC
1
Número de citas
0
Número de citas referidas
0
Descripción
Although variability is a general property of AGN, and in LINERs variations in timescales of months/years have been found for some objects, it is not clear how these changes occur. The main purpose of this work is to investigate the X-ray variability in LINERs, including the main driver of such variations. We use the 18 LINERs in the Palomar sample with data at different epochs available in Chandra and/or XMM-Newton archives. All the spectra for the same object are simultaneously fitted to study long term variations. The nature of the variability pattern was studied allowing the different parameters to vary during the spectral fit. Whenever possible, short term variations and UV variability are studied. Short term variations are not found at X-rays. Taking into account the data at X-rays (seven out of 12 objects) and UV (five out of six), ten out of 13 LINERs show long term variations. The main driver of the X-ray variations is related to changes in the nuclear power, while changes on absorptions are found only in one case. According to their BH masses, accretion rates and variability timescales, LINERs behave as more powerful AGN at X-rays. However, we conclude that a different accretion mechanism (compared to more powerful AGN) may be present, based on the anticorrelation between Γ and the Eddington ratio.