Significant Variability Observed in Luminous Type 2 Quasar at z = 2.99

A recent study published on arXiv presents a detailed analysis of WISEA J171419.96+602724.6, a luminous type 2 quasar located at a redshift of z = 2.99. The research, conducted by Xiurui Zhao and ten co-authors, reveals significant variability in the X-ray emissions of this quasar over a period of less than 2.5 years. Initial observations suggested that the quasar might be Compton-thick, indicating a high level of obscuration. However, new data from 2021 using NuSTAR and XMM-Newton showed a lower obscuration level, approximately 5 × 10²² cm⁻², and a reduction in flux by about four times compared to earlier measurements.

The findings indicate that the quasar exhibits variability in X-ray obscuration, flux, and intrinsic luminosity, with variations detected at 2-3 sigma significance. The study also includes spectral energy distribution (SED) fitting, which highlights the quasar's bolometric luminosity at approximately 2.5 × 10⁴⁷ erg s⁻¹. Additionally, the host galaxy of the quasar has a substantial star formation rate of around 1280 solar masses per year and a stellar mass of about 1.1 × 10¹² solar masses.

The correlation between the star formation rate and stellar mass aligns with observations of high-redshift quasars and main-sequence star-forming galaxies, suggesting that the active nucleus does not significantly influence the star formation rate of its host galaxy. This quasar is characterized as an infrared hyper-luminous, obscured galaxy, containing a significant amount of hot dust in its torus, and shares properties with other hot, dust-obscured galaxies.

These findings contribute to the understanding of quasar behavior and the characteristics of their host galaxies, providing insights into the evolution of galaxies in the early universe. The full paper can be accessed at arXiv:2409.01960.