| Issue |
A&A
Volume 672, April 2023
|
|
|---|---|---|
| Article Number | L9 | |
| Number of page(s) | 8 | |
| Section | Letters to the Editor | |
| DOI | https://doi.org/10.1051/0004-6361/202346316 | |
| Published online | 14 April 2023 | |
Letter to the Editor
Discovery of the lensed quasar eRASS1 J050129.5−073309 with SRG/eROSITA and Gaia⋆
1
Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, 14482 Potsdam, Germany
e-mail: dtubin@aip.de
2
Potsdam University, Institute for Physics and Astronomy, Karl-Liebknecht-Straße 24/25, 14476 Potsdam, Germany
3
Max-Planck-Institut für extraterrestrische Physik, Gießenbachstraße 1, 85748 Garching, Germany
4
Saitama University, 255 Shimookubo, Sakura Ward, Saitama, Japan
Received:
3
March
2023
Accepted:
5
April
2023
We report the discovery and spectroscopic identification of the bright doubly lensed quasar eRASS1 J050129.5−073309 at redshift z = 2.47, selected from the first all-sky survey of the Spectrum Roentgen Gamma (SRG) eROSITA telescope and the Gaia EDR3 catalog. We systematically searched for extragalactic sources with eROSITA X-ray positions that have multiple Gaia counterparts, and we have started spectroscopic follow-up of the most promising candidates using long-slit spectroscopy with NTT/EFOSC2 to confirm the lens nature. The two images are separated by 2.7″, and their average Gaia g-band magnitudes are 16.95 and 17.33. Legacy Survey DR10 imaging and image modeling reveal both the lensing galaxy and tentatively the lensed image of the quasar host galaxy. Archival optical light curves show evidence of a variability time delay, with the fainter component lagging the brighter by about 100 days. The brightness of the fainter image has also decreased by about one magnitude since 2019. This dimming was still obvious at the time of the spectroscopic observations and is probably caused by microlensing. The optical spectroscopic follow-up obtained from NTT/EFOSC2 and the evidence provided by the imaging and timing analysis allow us to confirm the lensed nature of eRASS1 J050129.5−073309.
Key words: gravitational lensing: strong / quasars: individual: eRASS1 J050129.5−073309 / X-rays: general
The light curves and the reduced spectra are only available at the CDS via anonymous ftp to cdsarc.cds.unistra.fr (130.79.128.5) or via https://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/672/L9
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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