X-ray quasi-periodic eruptions from the galactic nucleus of RX J1301.9+2747. (arXiv:2002.08967v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Giustini_M/0/1/0/all/0/1">Margherita Giustini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miniutti_G/0/1/0/all/0/1">Giovanni Miniutti</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saxton_R/0/1/0/all/0/1">Richard D. Saxton</a>
Following the recent discovery of X-ray quasi-periodic eruptions (QPEs) from
the nucleus of the galaxy GSN 069, we report here on the detection of QPEs in
the active galaxy RX J1301.9+2747. QPEs are rapid and recurrent increases of
the X-ray count-rate by more than one order of magnitude with respect to a
stable quiescent level. During a 48 ks long XMM-Newton observation performed on
30 and 31 May 2019, three strong QPEs lasting about half an hour each were
detected in the light curves of RX J1301.9+2747. The first two QPEs are
separated by a much longer recurrence time (about 20 ks) compared to the second
and third (about 13 ks); this pattern is consistent with the alternating
long-short recurrence times of the GSN 069 QPEs. Longer X-ray observations will
better clarify the temporal pattern of the QPEs in RX J1301.9+2747 and will
allow to perform a detailed comparison with GSN 069. The X-ray spectral
properties of QPEs in the two sources are remarkably similar, with QPEs
representing fast transitions from a relatively cold and likely disc-dominated
state to a state characterized by warmer emission similar to the so-called soft
X-ray excess, a component that is almost ubiquitously seen in the X-ray spectra
of unobscured, radiatively efficient active galaxies. Previous X-ray
observations of RX J1301.9+2747 in 2000 and 2009 strongly suggest that QPEs
have been present for at least the past 18.5 years. The detection of QPEs from
a second galactic nucleus after GSN 069 rules out contamination by a Galactic
source in both cases, so that QPEs have to be considered as a novel
extragalactic phenomenon associated with accreting supermassive black holes.
Following the recent discovery of X-ray quasi-periodic eruptions (QPEs) from
the nucleus of the galaxy GSN 069, we report here on the detection of QPEs in
the active galaxy RX J1301.9+2747. QPEs are rapid and recurrent increases of
the X-ray count-rate by more than one order of magnitude with respect to a
stable quiescent level. During a 48 ks long XMM-Newton observation performed on
30 and 31 May 2019, three strong QPEs lasting about half an hour each were
detected in the light curves of RX J1301.9+2747. The first two QPEs are
separated by a much longer recurrence time (about 20 ks) compared to the second
and third (about 13 ks); this pattern is consistent with the alternating
long-short recurrence times of the GSN 069 QPEs. Longer X-ray observations will
better clarify the temporal pattern of the QPEs in RX J1301.9+2747 and will
allow to perform a detailed comparison with GSN 069. The X-ray spectral
properties of QPEs in the two sources are remarkably similar, with QPEs
representing fast transitions from a relatively cold and likely disc-dominated
state to a state characterized by warmer emission similar to the so-called soft
X-ray excess, a component that is almost ubiquitously seen in the X-ray spectra
of unobscured, radiatively efficient active galaxies. Previous X-ray
observations of RX J1301.9+2747 in 2000 and 2009 strongly suggest that QPEs
have been present for at least the past 18.5 years. The detection of QPEs from
a second galactic nucleus after GSN 069 rules out contamination by a Galactic
source in both cases, so that QPEs have to be considered as a novel
extragalactic phenomenon associated with accreting supermassive black holes.
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