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تسجيل مستخدم جديدPredicting the spectrum of UGC 2885, Rubins Galaxy with machine learning
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Benne W. Holwerda
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Wu & Peek (2020) predict SDSS-quality spectra based on Pan-STARRS broad-band textit{grizy} images using machine learning (ML). In this letter, we test their prediction for a unique object, UGC 2885 (Rubins galaxy), the largest and most massive, isolated disk galaxy in the local Universe ($D<100$ Mpc). After obtaining the ML predicted spectrum, we compare it to all existing spectroscopic information that is comparable to an SDSS spectrum of the central region: two archival spectra, one extracted from the VIRUS-P observations of this galaxy, and a new, targeted MMT/Binospec observation. Agreement is qualitatively good, though the ML prediction prefers line ratios slightly more towards those of an active galactic nucleus (AGN), compared to archival and VIRUS-P observed values. The MMT/Binospec nuclear spectrum unequivocally shows strong emission lines except H$beta$, the ratios of which are consistent with AGN activity. The ML approach to galaxy spectra may be a viable way to identify AGN supplementing NIR colors. How such a massive disk galaxy ($M^* = 10^{11}$ M$_odot$), which uncharacteristically shows no sign of interaction or mergers, manages to fuel its central AGN remains to be investigated.
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