European astronomers report the detection of a powerful new radio quasar at a redshift of about 5.32. The new object, designated PSO J191.05696+86.43172, turns out to be one of the brightest radio quasars identified at such a high redshift. The discovery is reported in an article published October 26 on arXiv.org.
Quasars, or quasi-stellar objects (QSOs), are extremely luminous active galactic nuclei (AGNs) containing supermassive central black holes with accretion disks. Their redshifts are measured from the strong spectral lines that dominate their visible and ultraviolet spectra.
Astronomers are particularly interested in discovering new high redshift quasars (at a redshift greater than 5.0) because they are the brightest and most distant compact objects in the observable universe. The spectra of these QSOs can be used to estimate the mass of supermassive black holes that constrain models of quasar evolution and formation. Additionally, high redshift QSOs that are also radio-bright are unique indicators of supermassive black hole activity in the early universe.
Now, a team of researchers led by Silvia Belladitta of the Brera Astronomical Observatory in Milan, Italy, has discovered a new high redshift quasar. The detection is the result of cross-checking data from three different surveys.
“In this paper, we present the discovery and first observations of PSO J191.05696+86.43172 (hereafter PSO J191+86), a powerful jet QSO at z=5.32, which was selected from the cross-correlation of the NRAO VLA Sky Survey (NVSS, Condon et al. 1998) in radio, the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS PS1, Chambers et al. 2016) in optics and the AllWISE Source Catalog ( Wright et al. 2010; Mainzer et al. 2011) in the mid-infrared (MIR),” the astronomers explained.
The study found that the PSO J191+86 shows a possible peak radio spectrum around about 1 GHz in the observed frame, which corresponds to 6.3 GHz in the quiescent frame. The researchers noted that if this turnover is confirmed by further observations, it will make the new quasar one of the strongest gigahertz peak spectrum (GPS) sources at such a high redshift ever. detected.
The flux density of PSO J191+86 has been measured at 74.2 mJy, meaning it is one of the brightest redshift radio quasars known to date. Additionally, the very high radio volume of the PSO J191+86 makes it similar to the early universe’s massive population of blazars.
Research has found that the kinetic age of PSO J191+86’s radio jets is between 150 and 460 years old. This finding suggests that PSO J191+86 may be one of the most recent GPS sources at such a high redshift. The study also allowed the team to estimate that the linear size of this quasar is between 32 and 100 light-years away.
As a conclusion, the authors of the article propose other radio observations in order to unveil the nature of PSO J191+86 and to shed more light on its properties.
S. Belladitta et al, A powerful (and probably young) radio-strong quasar at z=5.3, arXiv (2022). DOI: 10.48550/arxiv.2210.14946
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