麻豆淫院

By analyzing multiwavelength data from various space telescopes and astronomical surveys, Chinese astronomers have explored the long-term variability of a blazar known as PKS 0727-11. Results of the new study, in The Astrophysical Journal, deliver more insights into the nature and behavior of this blazar.

Blazars are very compact quasars associated with supermassive black holes (SMBHs) at the centers of active, giant elliptical galaxies. They belong to a larger group of active galaxies that host active galactic nuclei (AGN), and are the most numerous extragalactic gamma-ray sources. Their characteristic features are relativistic jets pointed almost exactly toward Earth.

Based on their optical emission properties, astronomers divide blazars into two classes: flat-spectrum radio quasars (FSRQs) that feature prominent and broad optical emission lines, and BL Lacertae objects (BL Lacs), which do not.

PKS 0727-11 is an FSRQ at a redshift of approximately 1.59, associated with the gamma-ray source 4FGL J0730.3-1141. It was first identified in 1966 as part of the Parkes catalog of radio sources.

Previous observations of PKS 0727-11 have found that it has an opaque microwave spectrum at 6.63 and 10.63 GHz. It also turned out that the blazar contains a compact component and showcases a rapid variability.

In order to better understand the behavior of PKS 0727-11, a team of astronomers led by Yuncai Shen of the Yunnan Normal University in China, has combed through various archival projects containing multiwavelength data from various space observatories and ground-based telescopes, including NASA's Fermi and Swift spacecraft.

"The gamma-ray data were retrieved from the public archive of the Fermi-LAT. X-ray data were taken from Swift-XRT monitoring of Fermi-LAT sources of interest, and the light curve in the 0.3-10 keV range was constructed using the reduced data from this archive. Optical R-band and near-infrared J-band data were obtained from the SMARTS program, while millimeter-wave data at 1 mm were retrieved from the SMA database. Additionally, radio observations at 4.8, 8.0, and 14.5 GHz were acquired from the UMRAO," the researchers explained.

First of all, Shen's team identified a possible quasi-periodic oscillation (QPO) in the gamma-ray light curve of PKS 0727-11. The so-called QPOs occur when X-rays are emitted near the inner edge of an accretion disk in which gas swirls onto a compact object; for instance, a neutron star or a black hole. However, QPOs have also been observed in the gamma-ray emission from blazars.

The detected QPO has a period of approximately 168.6 days. The astronomers assume that the QPO in PKS 0727-11 may arise due to the non-ballistic helical motion driven by the orbital motion in a close supermassive binary black hole. In this scenario, the mass of the primary black hole is estimated to be between 0.36 and 5.79 billion solar masses.

Furthermore, the study found that there is a strong correlation between multiband light variations of PKS 0727-11. This suggests that the gamma-ray and radio flares of this blazar may originate from the same disturbance.

The astronomers also estimated the distance between the gamma-ray and 1-mm band emission regions in PKS 0727-11, which was found to be approximately 43.65 light years.

漏 2025 Science X Network