The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41
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...
| Hlavní autoři: | , , , |
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| Médium: | Článek |
| Jazyk: | English |
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IOP Publishing
2023-01-01
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| Edice: | The Astrophysical Journal |
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| On-line přístup: | https://doi.org/10.3847/1538-4357/acd17f |
| _version_ | 1827829438367137792 |
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| author | Avik Kumar Das Raj Prince Alok C. Gupta Pankaj Kushwaha |
| author_facet | Avik Kumar Das Raj Prince Alok C. Gupta Pankaj Kushwaha |
| author_sort | Avik Kumar Das |
| collection | DOAJ |
| description | 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 (∼4.1 σ ). 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. |
| first_indexed | 2024-03-12T04:04:03Z |
| format | Article |
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| institution | Directory Open Access Journal |
| issn | 1538-4357 |
| language | English |
| last_indexed | 2024-03-12T04:04:03Z |
| publishDate | 2023-01-01 |
| publisher | IOP Publishing |
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| series | The Astrophysical Journal |
| spelling | doaj.art-db1657f098224cf88a16a5a80ed1f5f42023-09-03T11:25:40ZengIOP PublishingThe Astrophysical Journal1538-43572023-01-01950217310.3847/1538-4357/acd17fThe Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41Avik Kumar Das0https://orcid.org/0000-0002-9526-0870Raj Prince1https://orcid.org/0000-0002-1173-7310Alok C. Gupta2https://orcid.org/0000-0002-9331-4388Pankaj Kushwaha3https://orcid.org/0000-0001-6890-2236Department of Physical Sciences, Indian Institute of Science Education and Research Mohali , Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India avikdas@iisermohali.ac.inCenter for Theoretical Physics, Polish Academy of Sciences , Al.Lotnikow 32/46, 02-668, Warsaw, PolandAryabhatta Research Institute of Observational Sciences (ARIES) , Manora Peak, Nainital 263001, IndiaDepartment of Physical Sciences, Indian Institute of Science Education and Research Mohali , Knowledge City, Sector 81, SAS Nagar, Punjab 140306, India avikdas@iisermohali.ac.inThe 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 (∼4.1 σ ). 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.https://doi.org/10.3847/1538-4357/acd17fActive galaxiesGamma-raysBlazars |
| spellingShingle | Avik Kumar Das Raj Prince Alok C. Gupta Pankaj Kushwaha The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41 The Astrophysical Journal Active galaxies Gamma-rays Blazars |
| title | The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41 |
| title_full | The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41 |
| title_fullStr | The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41 |
| title_full_unstemmed | The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41 |
| title_short | The Detection of Possible Transient Quasiperiodic Oscillations in the γ-Ray Light Curve of PKS 0244-470 and 4C+38.41 |
| title_sort | detection of possible transient quasiperiodic oscillations in the γ ray light curve of pks 0244 470 and 4c 38 41 |
| topic | Active galaxies Gamma-rays Blazars |
| url | https://doi.org/10.3847/1538-4357/acd17f |
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