QSO HE 0435-5304 redshift solved

Małgorzata Bankowicz, Aleksander Herzig, Agnieszka Pollo, Katarzyna Małek

We report a spectroscopic redshift measurement of quasar HE 0435-5304. Up to now, this particular quasar had two conflicting values of redshift used in the literature: 1.231 measured from an optical spectrum by Wisotzki et al. (2000), and ∼0.43 obtained based on ultraviolet spectra by Stocke et al. (2013). The z=1.231 value is more widely used and listed as the "preferred redshift" in the NASA/IPAC Extragalactic Database and SIMBAD databases. However, com- bined with photometric multiwavelength measurements, this redshift value makes the HE 0435-5304 host a very extreme and even peculiar galaxy in terms of star formation, as found by Małek et al. (2017), while at z∼0.43 HE 0435-5304 remains a fairly typical example of a Luminous Infrared Galaxy. To clarify this issue, we analysed an optical spectrum of HE 0435-5304 obtained by the Robert Stobie Spectrograph at the South African Large Telescope (SALT) as a part of our project to study properties and environments of infrared sources around the South Ecliptic Pole. Based on five clearly identified emission lines we estimated the redshift of this quasar to be z = 0.45, in agreement with the value reported by Stocke et al. (2013), and definitely ruling out the "preferred redshift" value by Wisotzki et al. (2000).

Proceedings of the Polish Astronomical Society, vol. 10, 267-271 (2020)

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