| Issue |
A&A
Volume 683, March 2024
|
|
|---|---|---|
| Article Number | L8 | |
| Number of page(s) | 6 | |
| Section | Letters to the Editor | |
| DOI | https://doi.org/10.1051/0004-6361/202348900 | |
| Published online | 13 March 2024 | |
Letter to the Editor
A newborn active galactic nucleus in a star-forming galaxy
1
Instituto de Física y Astronomía, Universidad de Valparaíso, Gran Bretaña 1111, Valparaíso, Chile
e-mail: patricia.arevalo@uv.cl
2
Millennium Nucleus on Transversal Research and Technology to Explore Supermassive Black Holes (TITANS), Chile
3
Astronomy Department, Universidad de Concepción, Casilla 160-C, Concepción 4030000, Chile
4
Departamento de Astronomía, Universidad de Chile, Casilla 36D, Santiago, Chile
5
European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany
6
Millennium Institute of Astrophysics (MAS), Monseñor Sótero Sanz 100, Providencia, Santiago, Chile
7
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, 85748 Garching, Germany
8
Exzellenzcluster ORIGINS, Boltzmannstr. 2, 85748 Garching, Germany
9
Instituto de Estudios Astrofísicos, Facultad de Ingeniería y Ciencias, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
10
Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
Received:
11
December
2023
Accepted:
29
February
2024
Aims. We report on the finding of a newborn active galactic nucleus (AGN), based on the observation of current AGN activity in a galaxy previously classified as non-active. We subsequently characterize the AGN’s evolution.
Methods. Black hole ignition event candidates were selected from a parent sample of spectrally classified non-active galaxies (2 394 312 objects), which currently show optical flux variability indicative of a type I AGN, according to the ALeRCE light curve classifier. A second epoch spectrum for a sample of candidate newborn AGNs was obtained with the SOAR telescope to search for new AGN features.
Results. We present the spectral results for the most convincing case of new AGN activity for a galaxy with a prior star-forming optical classification, where the second epoch spectrum shows the appearance of prominent, broad Balmer lines, without any significant changes seen in the narrow line flux ratios. The long-term optical light curves show a steady increase in luminosity starting 1.5 years after the SDSS spectrum was taken and continuing for at least 7 years. Mid-infrared (MIR) colors from the WISE catalog have also evolved from typical non-active galaxy colors to AGN-like colors. Recent X-ray flux detections confirm its nature as an AGN.
Key words: galaxies: active / quasars: emission lines / quasars: supermassive black holes / galaxies: Seyfert
© The Authors 2024
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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