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Observational Insights into Optical Variability of Blazar S5 0716+714
A collaborative effort between astronomers from Turkey and India, utilizing the TÜBİTAK National Observatory, has brought new insights into the dynamic behavior of the blazar S5 0716+714. These findings, detailed in a recent publication on arXiv, shed light on the optical variability of this intriguing celestial object.
Understanding Blazars
Blazars, highly compact quasars linked to supermassive black holes (SMBHs) at the core of active, massive elliptical galaxies, belong to a broader category of active galaxies hosting active galactic nuclei (AGN). Notably, they rank as the most prolific extragalactic gamma-ray sources, distinguished by their relativistic jets that are directed almost directly towards Earth.
Astrophysicists classify blazars into two distinct categories based on their optical emission characteristics: flat-spectrum radio quasars (FSRQs), which exhibit prominent and broad optical emission lines, and BL Lacertae objects (BL Lacs), which lack such features.
The blazar S5 0716+714, identified in 1979 during a survey of extragalactic radio sources, stands out with a redshift of 0.23. This object is recognized as one of the brightest and most active members of the BL Lac category.
Recent Observational Campaigns
S5 0716+714’s notable optical variability has led to multiple monitoring efforts, with the latest being executed by a team under the leadership of Ergün Ege from Istanbul University. Employing the T60 and T100 telescopes from the TÜBİTAK National Observatory, the team conducted observations spanning from March 2019 to August 2023.
The researchers noted, “We present the results of the observational study of the blazar S5 0716+714 in the optical bands B, V, R, and I to investigate its variability across different timescales.”
Key Findings
The observational data revealed that the brightness of S5 0716+714 fluctuated between 12.11 and 14.58 in the optical R-band. The long-term light curve highlights a variability amplitude of approximately 256.12%, 247.08%, 247.04%, and 230.21% in the B, V, R, and I bands, respectively.
Moreover, the study examined intraday variability (IDV), finding that the blazar exhibited significant variability in the R-band across 12 out of 21 observation nights. On these occasions, the blazar’s brightness varied by about 0.1 magnitude, with variability amplitudes ranging from 4.41 to 11.23 across the BVRI bands.
In terms of periodic behavior, the study identified potential quasi-periods of approximately 186 and 532 days in the R-band light curve. The researchers speculate that the 186-day quasi-period oscillation (QPO) may correspond to two outbursts of S5 0716+714 that occurred in May and October 2021.
Additionally, through their extensive dataset, the researchers estimated the size of the emission region around S5 0716+714 to be about 67 astronomical units (AU), while calculating the mass of its associated SMBH to be approximately 569 million solar masses.
Further Reading
More information:
Ergün Ege et al, Investigating Optical Variability of the Blazar S5 0716+714 On Diverse Time-scales, arXiv (2024). DOI: 10.48550/arxiv.2407.09419
Source
phys.org