https://phys.org/news/2020-03-x-ray-quasi-periodic-eruptions-galaxy-rx.html X-ray quasi-periodic eruptions detected in the galaxy RX J1301.9+2747 by Tomasz Nowakowski , Phys.org Please Register or Log in to view the hidden image! Background-corrected light curves of RX J1301.9+2747, extracted with time bins of 300 s in the 0.2−2 keV band during the 10-11 December 2000 (left panels) and the 30-31 May 2019 (right panels) XMM-Newton observations. Bottom panels: the count rates have been normalised to the quiescent level. In black EPIC-pn, in red EPIC-MOS1, in green EPIC-MOS2 data. Credit: Giustini et al., 2020. Astronomers have performed observations of a galaxy known as RX J1301.9+2747 using ESA's XMM-Newton spacecraft. The study unveiled three strong and rapid X-ray quasi-periodic eruptions (QPEs) in the nucleus of this galaxy. The finding is reported in a paper published February 20 on arXiv.org. more at link....... the paper: https://arxiv.org/pdf/2002.08967.pdf X-ray quasi-periodic eruptions from the galactic nucleus of RX J1301.9+2747: ABSTRACT 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. Conclusions: During a 48 ks XMM-Newton observation performed in May 2019, three strong and rapid X-ray QPEs have been detected in the nucleus of the galaxy RX J1301.9+2747. These QPEs seem to be long-lived: in fact, about 1.5 QPEs with similar properties to those of 2019 were detected in a 2000 archival XMM-Newton observation of RX J1301.9+2747 (Sun et al. 2013), and also observations performed by ROSAT in 1994 (Dewangan et al. 2000) and by Chandra in 2009 (Shu et al. 2017) revealed interesting X-ray variability properties, with sudden increases or decreases in X-ray count rate above a stable low-flux level. The general properties of the X-ray QPEs observed in RX J1301.9+2747 are similar to those of the QPEs observed in the discovery source GSN 069 (Miniutti et al. 2019): their merged spectrum looks like a thermal component (with a temperature of about 100-300 eV, depending on spectral modelling), with a 0.2−2 keV intrinsic luminosity of the order of 1042 erg s−1 , about one order of magnitude higher than the luminosity of the quiescent level. There are also clear differences between the QPEs observed in RX J1301.9+2747 and GSN 069. Not only the QPEs in RX J1301.9+2747 are shorter than those in GSN 069, but their time separation looks generally also shorter. The QPEs observed in GSN 069 during the 2018-2019 campaigns follow a clear long-short-long-short pattern in terms of recurring times; this could be the case also for RX J1301.9+2747, and this possibility can be checked with longer X-ray observations. The quiescent spectrum of RX J1301.9+2747 is well described by a thermal disk with a temperature of 50 eV and a 0.2 − 2 keV luminosity of about 1041 erg s−1 , constant between the 18.5 years between the two XMM-Newton observations; plus a weak hard X-ray power law, whose 0.2 − 2 keV luminosity more than tripled between 2000 and 2019, when it is still however < 5 × 1040 erg s−1 . Also the spectrum of the QPE changed between 2000 and 2019, having become harder: this might mean that in the time elapsed between the two observations the temperature of the QPE has increased, and/or that in 2019 the power law emission is also contributing to the QPE, contrary to 2000. While in GSN 069 the QPEs are detected during the overall ∼ 10 years-long (so far) decay following an outburst first detected in 2010, the QPEs of RX J1301.9+2747 are detected during two observations ∼ 18.5 years apart and at a similar flux/luminosity level. Very long-lived tidal disruption events may perhaps explain the long-term evolution of both sources (e.g., MacLeod et al. 2012; Lin et al. 2017), but the lack of overall decay in RX J1301.9+2747 could instead argue against this possibility. From a phenomenological point of view, the QPE spectral evolution can be described as a transient and fast transition from a disk-dominated to a soft-excess-dominated state and, if so, QPEs may provide crucial clues on the origin of this X-ray spectral component which is almost ubiquitous in unobscured, radiatively efficient AGN. The question whether QPEs are directly associated with accretion flow variability and/or instabilities or due instead to extrinsic phenomena (such as interactions with a secondary orbiting body) remains to be studied. Future X-ray observations of both sources will enable us to constrain possible theoretical models taking advantage of the different properties and timescales in the two sources, which need to be consistent with a similar theoretical framework. The detection of X-ray QPEs in RX J1301.9+2747 doubles the number of galactic nuclei where this new phenomenon has been observed, after their discovery in GSN 069. This rules out contamination by a Galactic source in both cases, assessing QPEs as a novel extragalactic phenomenon associated to supermassive accreting black holes.
The query that arises from this from my point of view, is what is the difference between these QPE's and FRB's, other then of course, duration?
