A Possible Quasi-Periodic Oscillation in the X-ray Emission of 3C 120

Agarwal, Aditi; Rani, Priyanka; Prince, Raj; Stalin, C. S.; Anupama, G. C.; Agrawal, V.

doi:10.3390/galaxies9020020

Cited by 6 publications

(3 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…To search for quasiperiodicity in the source, we used a large number of analysis techniques (Foster 1996;Agarwal et al 2021a, and references therein), e.g., structure function (SF), DACF, weighted wavelet Z-transform (WWZ), and Lomb-Scargle periodogram (LSP). For the DACF, we considered the detection to be significant if the DACF values were greater than 0.5.…”

Section: Cross-correlation Analysis and Periodicity Searchmentioning

confidence: 99%

Characterizing the Optical Nature of the Blazar S5 1803+784 during Its 2020 Flare

Agarwal

Pandey

Özdönmez

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

We report the results from our study of the blazar S5 1803+784 carried out using quasi-simultaneous B, V, R, and I observations from 2020 May to 2021 July on 122 nights. Our observing campaign detected a historically bright optical flare during MJD 59,063.5−MJD 59,120.5. We also found the source in its brightest (R mag = 13.617) and faintest (R mag = 15.888) states to date. On 13 nights, covering both flaring and nonflaring periods, we searched for intraday variability using the power-enhanced F-test and the nested ANOVA test. We found significant variability in 2 of these 13 nights. However, no such variability was detected during the flaring period. From correlation analysis, we observed that the emission in all optical bands were strongly correlated with a time lag of ∼0 days. To get insights into its dominant emission mechanisms, we generated the optical spectral energy distributions of the source on 79 nights and estimated the spectral indices by fitting a simple power law. The spectral index varied from 1.392 to 1.911 and showed significant variations with time and R-band magnitude. We detected a mild bluer-when-brighter (BWB) trend during the whole monitoring period and a much stronger BWB trend during the flare. We also carried out a periodicity search using four different methods and found no significant periodicity during our observation period. Based on the analysis during the flaring state of the source one can say that the emissions most likely originate from the jet rather than from the accretion disk.

show abstract

Section: Cross-correlation Analysis and Periodicity Searchmentioning

confidence: 99%

Characterizing the Optical Nature of the Blazar S5 1803+784 during Its 2020 Flare

Agarwal

Pandey

Özdönmez

et al. 2022

ApJ

Self Cite

View full text Add to dashboard Cite

show abstract

“…Since 2008, the detection or reporting of such QPOs in blazars and in other subclasses of AGNs has been increased-mainly due to much better data sampling as a result of coordinated MW follow-ups under the Fermi AGN Monitoring Program. Many strong QPOs have been reported across the complete EM bands in many sources on different timescales ranging from minutes to hours to days and to years (e.g., Gierliński et al 2008;Gupta et al 2009;Lachowicz et al 2009;King et al 2013;Alston et al 2014;Gupta 2014;Ackermann et al 2015;Alston et al 2015;Pan et al 2016;Gupta et al 2018;Gupta 2018;Zhou et al 2018;Gupta et al 2019;Agarwal et al 2021;Tripathi et al 2021 and references therein).…”

Section: Introductionmentioning

confidence: 99%

The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41

Das¹,

Prince

Gupta

et al. 2023

ApJ

Self Cite

View full text Add to dashboard Cite

The continuous monitoring capability of Fermi-LAT has enabled the exploration of quasiperiodic oscillations (QPOs) in the γ-ray light curve of blazars that has given a new perspective to probe these sources over a wide range of timescales. We report the presence of transient QPOs in the long-term γ-ray light curve of blazars PKS 0244-470 and 4C +38.41. We first identified different flux states using the Bayesian block algorithm and then explored the possible transient QPOs in the segments of each flux phase where the flux level changes over fairly regular intervals. Combining this with the source’s intrinsic variance, we identified two flux phases for PKS 0244-470: one activity (AP-1) and one quiescent phase (QP-1). For 4C+38.41, we similarly identified four activity (AP-1, AP-2, AP-3, and AP-4) and two quiescent (QP-1 and QP-2) phases. The AP-1 phase of PKS 0244-470 shows QPO of ∼225 days persisting for eight cycles (∼4.1σ). In 4C+38.41, AP-1 and AP-2 phases show QPO-like behavior of ∼110 days and ∼60 days, respectively, persisting for five cycles. In AP-3, we identified three subphases, and all show a ∼7 day scale possible recurrent rise with five complete cycles, while in QP-1, we could identify two subphases (Q1 and Q2). The Q1 phase shows a period of ∼104 days with six complete cycles. The Q2 phase also shows QPO but with only ∼3.7 cycles. We discuss the possible origin and argue that the current-driven kink instability and curved jet model seem to be the most likely causes for shorter and longer QPOs.

show abstract

“…However, transient Quasi-Periodic Oscillations (QPOs) have mainly been observed in galactic X-ray binaries and micro-quasars systems, where the accretion disk and corona mostly power the emission (Remillard & McClintock 2006). Since 2008, the detection or reporting of QPOs in blazars -both transient and persistent (relative), and in other subclasses of AGN have been increased -mainly due to much better data sampling as a result of coordinated MW follow-ups under the Fermi AGN Monitoring Program, and strong QPOs are reported across the complete EM bands in many sources on different time scales ranging from minutes to hours to days and to years (e.g., Gierliński et al 2008;Lachowicz et al 2009;Gupta et al 2009Gupta et al , 2018Gupta et al , 2019King et al 2013;Alston et al 2014Alston et al , 2015Gupta 2014Gupta , 2018Ackermann et al 2015;Pan et al 2016;Zhou et al 2018;Agarwal et al 2021;Tripathi et al 2021, and references therein).…”

Section: Introductionmentioning

confidence: 99%

The detection of possible transient Quasi-Periodic Oscillations in the $γ$-ray light curve of PKS 0244-470 and 4C+38.41

Das¹,

Prince²,

Gupta³

et al. 2022

Preprint

View full text Add to dashboard Cite

The continuous monitoring capability of Fermi-LAT has enabled the exploration of Quasi-Periodic Oscillations (QPOs) in the γ-ray light curve of blazar that has given a new perspective to probe these source and jet physics over a wide range of time scales. We report the presence of transient QPOs in the long-term γ-ray light curve of blazars PKS 0244-470 & 4C +38.41. We first identified different flux states using the Bayesian Block algorithm and then explored the possible transient QPOs in the segments of each flux phase where the flux level changes over fairly regular intervals. Combining this with source intrinsic variance, we identified two flux phases for PKS 0244-470: one activity (AP-1) and one quiescent phase (QP-1). For 4C+38.41, we similarly identified four activity (AP-1, AP-2, AP-3, and AP-4) and two quiescent (QP-1 and QP-2) phases. AP-1 phase of PKS 0244-470 shows QPO of ∼ 225 days persisting for 8 cycles (∼ 4.1 σ). In 4C+38.41, AP-1 and AP-2 phases show QPO of ∼ 110 days and ∼ 60 days, respectively, persisting for 5 cycles. In AP-3, we identified three sub-phases, and all show a ∼ week scale recurrent rise with five complete cycles, while in QP-1, we could identify 2 sub-phases (Q1 and Q2). Q1 phase shows a significant period of ∼ 104 days with six complete cycles. Q2 phase also shows significant QPO but with only ∼ 3.7 cycles. All the detections are locally significant with at least four or more cycles. We discuss the possible origin and argue that the current driven kink instability and curved jet model seem the most likely cause for shorter and longer QPOs though the latter requires continuous acceleration or injection of particles to explain these.

show abstract

A Possible Quasi-Periodic Oscillation in the X-ray Emission of 3C 120

Cited by 6 publications

References 69 publications

Characterizing the Optical Nature of the Blazar S5 1803+784 during Its 2020 Flare

Characterizing the Optical Nature of the Blazar S5 1803+784 during Its 2020 Flare

The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41

The detection of possible transient Quasi-Periodic Oscillations in the $γ$-ray light curve of PKS 0244-470 and 4C+38.41

Contact Info

Product

Resources

About