Blazar 1ES 1959+650 studied by Swift and XMM-Newton satellites

Using NASA’s Swift Observatory and ESA’s XMM-Newton satellite, Indian astronomers have examined the prominent synchrotron star with a peak known as 1ES 1959+650. Results of the study published May 5 on arXiv Prepress Server, sheds more light on the nature of this resource.

Blazars are very compact quasars supermassive black holes (SMBHs) at the centers of active giant elliptical galaxies. They belong to a larger group of active host galaxies active galactic nuclei (AGN), the most massive extragalactic source of gamma rays. Its distinguishing features are relative planes Pointing almost exactly towards the ground.

Based on their optical emission properties, astronomers divide blazars into two classes: Flat spectrum radio quasars (FSRQs) that have prominent, broad visual emission lines, and BL Lacertae (BL Lacs), which do not. Some blazars are high peak synchrotron sources (HSP) as their synchrotron peak is above 1000 THz in the rest frame. Observations show that particles are efficiently accelerated to very high energies (VHEs) in the jets of HSPs, which makes these sources very exciting for astronomers studying intense blazars.

At a redshift of about 0.048, 1ES 1959+650 is a prominent close HSP Blazar where the synchrotron peak of the spectral energy distribution (SED) appears in the UV/X-ray range. It shows strong flux contrast in the optical, X-ray, and TeV energy bands and experienced unprecedented X-ray flaring activity between August 2015 and January 2016.

Recently, a team of astronomers led by Kiran A. Wani of the Aryabhata Research Institute of Observational Sciences (ARIES) in India, analyzed Swift and XMM-Newton observations of 1ES 1959+650, with the main aim of investigating the temporal and spectral arcs. This BLAZER fluctuates on time scales from minutes to years covering different flow states.

“Swift-XRT and XMM-Newton EPIC-pn observations were used to study HSP 1ES 1959+650 during the period June 2018 to December 2020 in a total of 127 nights of observations,” the researchers wrote in the paper.

The study detected significant variability in 1ES 1959+650 on seven observation nights with the amplitude of flux variability ranging from 1.95% to 3.12%. The time scale for the flux doubling was found to be about 15,270 seconds and the mass of the black hole was calculated to be about 295 million solar masses.

Observations show that 1ES 1959+650 exhibits log-normal behavior on long-term time scales. Astronomers hypothesize that such behavior could be attributed to the minijets-in-a-jet model or could be due to the propagation of relativistic shocks below the Blazar jet.

The research also found that on long time scales, 1ES 1959+650 showed high as well as low flow states. Moreover, analysis of the hardness ratio over long-term time scales indicates that blazars follow a so-called ‘harder when brighter’ trend.

the Astronomy scientists I was also able to estimate the magnetic field strength of the emission region at 1ES 1959+650 – which was found to be approximately 0.64 Gauss. This is consistent with previous results.

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