Two Transient X-Ray Quasi-periodic Oscillations Separated by an Intermediate State in 1H 0707-495

Zhang, Peng-Fei; Zhang, Peng; Liao, Neng-Hui; Yan, Jiangli; Fan, Yi‐Zhong

doi:10.3847/1538-4357/aaa29a

Cited by 43 publications

(36 citation statements)

References 40 publications

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“…However, if so, it should not be the only factor of importance, because otherwise the detection of MPs in younger massive clusters should also be expected. This conclusion is consistent with that of Zhang et al (2018). It is important to search for MPs in other clusters of similar ages but lower masses than NGC 2121, such as NGC 2193 and ESO-56-SC40 (Baumgardt et al 2013).…”

Section: Discussion and Summarysupporting

confidence: 88%

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When Does the Onset of Multiple Stellar Populations in Star Clusters Occur? Detection of Enriched Stellar Populations in NGC 2121

Grijs

2019

ApJ

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Star-to-star light-element abundance variations, know as multiple stellar populations (MPs), are common in almost all Galactic globular clusters. Recently, MPs have also been detected in a number of massive clusters with ages in excess of 2 Gyr in the Large Magellanic Cloud (LMC), thus indicating that age is likely a control parameter for the presence of MPs. However, to conclusively confirm this notion, additional studies of star clusters in the LMC's 'age gap' of 3-6 Gyr are required. Here, we use Hubble Space Telescope observations to study the 3 Gyr-old cluster NGC 2121. Compared with so-called 'simple' stellar population models, the cluster's red-giant branch exhibits an apparent spread in a specific color index that is sensitive to intrinsic chemical spreads. The observed spread can be explained by an intrinsic spread in nitrogen abundance of ∼0.5-1.0 dex. NGC 2121 has a comparable mass to its younger counterparts without MPs, indicating that cluster mass might not be the dominant parameter controlling the presence of MPs. The transition phase between the occurrence of clusters with or without MPs seems to occur at ages of 2-3 Gyr, indicating that cluster age may play a dominant role in the establishment of MPs.

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Section: Discussion and Summarysupporting

confidence: 88%

“…It is useful to compare the physical properties of NGC 2121 with those of its younger counterparts without MPs, i.e., NGC 1783, NGC 1806, and NGC 1846(Mucciarelli et al 2014Martocchia et al 2018;Zhang et al 2018 2018). These clusters also have similar metallicities and distances to the LMC's bar region ).…”

Section: Discussion and Summarymentioning

confidence: 99%

When Does the Onset of Multiple Stellar Populations in Star Clusters Occur? Detection of Enriched Stellar Populations in NGC 2121

Grijs

2019

ApJ

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“…However, a systematic study of power spectra of 104 AGNs by González-Martín & Vaughan (2012) resulted in no conclusive detections of QPOs, except for RE J1034+36. Possible detections of QPOs ( f QPO ∼ [0.7 − 2.7] × 10 −4 Hz) were reported in a few other AGNs from dedicated searches, including 2XMM J123103.2+110648 (J1231, Lin et al 2013), MS2254.9-3712 (Alston et al 2015), 1H 0707-495 (Pan et al 2016;Zhang et al 2018), Mrk 766 (Zhang et al 2017), and MCG -6-30-15 (Gupta et al 2018). In addition, QPOs were also detected in the stellar tidal disruption events (TDEs) by SMBHs where transient accretion is triggered (Reis et al 2012;Pasham et al 2019).…”

Section: Introductionmentioning

confidence: 98%

Possible ∼0.4 h X-ray quasi-periodicity from an ultrasoft active galactic nucleus

Song

Shu

Sun

et al. 2020

A&A

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RX J1301.9+2747 is an ultrasoft active galactic nucleus (AGN) with unusual X-ray variability that is characterized by a long quiescent state and a short-lived flare state. The X-ray flares are found to recur quasi-periodically on a timescale of 13-20 ks. Here, we report the analysis of the light curve in the quiescent state from two XMM-Newton observations spanning 18.5 years, along with the discovery of a possible quasi-periodic X-ray oscillation (QPO) with a period of ∼1500s. The QPO is detected at the same frequency in the two independent observations, with a combined significance of >99.89%. The QPO is in agreement with the relation between frequency and black hole mass (M BH) that has been reported in previous works for AGNs and Galactic black hole X-ray binaries (XRBs). The QPO frequency is stable over almost two decades, suggesting that it may correspond to the high-frequency type found in XRBs and originates, perhaps, from a certain disk resonance mode. In the 3:2 twin-frequency resonance model, our best estimate on the M BH range implies that a maximal black hole spin can be ruled out. We find that all ultrasoft AGNs reported so far display quasiperiodicities in the X-ray emission, suggesting a possible link on the part of the extreme variability phenomenon to the ultrasoft X-ray component. This indicates that ultrasoft AGNs could be the most promising candidates in future searches for X-ray periodicities.

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“…Indeed, the first AGN X-ray QPO was discovered in the NLS1 RE J1034+396 with a period of 3730 ± 60 s (Gierliński et al 2008). Since then a few X-ray QPOs with lower significances have been reported in NLS1s, such as 1H 0707−495 (Pan et al 2016;Zhang et al 2018), MS 2254.9−3712 (Alston et al 2015), Mrk 766 (Zhang et al 2017), (Gupta et al 2018). A couple of Seyfert 2s were also reported to exhibit a QPO, including 2XMM J123103.2+110648 (Lin et al 2013) and XMMU J134736+173403 (Carpano & Jin 2018).…”

mentioning

confidence: 99%

Reobserving the NLS1 galaxy RE J1034+396 – I. The long-term, recurrent X-ray QPO with a high significance

Jin

Done

Ward

2020

Monthly Notices of the Royal Astronomical Society

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RE J1034+396 is a narrow-line Seyfert 1 galaxy (NLS1) in which the first significant X-ray quasi-periodic oscillation (QPO) in an active galactic nucleus (AGN) was observed in 2007. We report the detection of this QPO in a recent XMM–Newton observation in 2018 with an even higher significance. The quality factor of this QPO is 20, and its period is 3550 ± 80 s, which is 250 ± 100 s shorter than in 2007. While the QPO’s period has no significant energy dependence, its fractional root mean square variability increases from 4 per cent in 0.3–1 keV to 12 per cent in 1–4 keV bands. An interesting phenomenon is that the QPO in 0.3–1 keV leads that in the 1–4 keV bands by 430 ± 50 s with a high coherence, opposite to the soft X-ray lag reported for the observation in 2007. We speculate that the QPO has an intrinsic hard lag, while the previous reported soft lag is caused by the interference of stochastic variability. This soft X-ray lead in the new data supports the idea that the QPO of RE J1034+396 is a possible AGN counterpart of the 67 Hz high-frequency QPO seen in the black hole binary GRS 1915+105. We also search for QPO harmonics, but do not find any significant signals. Our new data reinforce previous results that the QPO is seen in a specific spectral state, as the only two observations showing no significant QPO signal exhibit an even stronger soft X-ray excess than the other six observations that display the QPO. Therefore, our results imply that the QPO in RE J1034+396 is physically linked to a soft X-ray component.

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Two Transient X-Ray Quasi-periodic Oscillations Separated by an Intermediate State in 1H 0707-495

Cited by 43 publications

References 40 publications

When Does the Onset of Multiple Stellar Populations in Star Clusters Occur? Detection of Enriched Stellar Populations in NGC 2121

When Does the Onset of Multiple Stellar Populations in Star Clusters Occur? Detection of Enriched Stellar Populations in NGC 2121

Possible ∼0.4 h X-ray quasi-periodicity from an ultrasoft active galactic nucleus

Reobserving the NLS1 galaxy RE J1034+396 – I. The long-term, recurrent X-ray QPO with a high significance

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