分类： 天文学 >> 天文学 提交时间： 2023-02-19
Helena P. Treiber
Jason T. Hinkle
Michael M. Fausnaugh
Benjamin J. Shappee
Christopher S. Kochanek
Patrick J. Vallely
Katie Auchettl
Thomas W. S. Holoien
Anna V. Payne
Xinyu Dai
摘要： We used Transiting Exoplanet Survey Satellite (TESS) data to identify 29 candidate active galactic nuclei (AGNs) through their optical variability. The high-cadence, high-precision TESS light curves present a unique opportunity for the identification of AGNs, including those not selected through other methods. Of the candidates, we found that 18 have either previously been identified as AGNs in the literature or could have been selected based on emission-line diagnostics, mid-IR colors, or X-ray luminosity. AGNs in low-mass galaxies offer a window into supermassive black hole (SMBH) and galaxy co-evolution and 8 of the 29 candidates have estimated black hole masses $\mathrm{\lesssim 10^{6} M_{\odot}}$. The low-mass galaxies NGC 4395 and NGC 4449 are two of our five "high-confidence" candidates. By applying our methodology to the entire TESS main and extended mission datasets, we expect to identify $\sim$45 more AGN candidates, of which $\sim$26 will be new and $\sim$8 will be in low-mass galaxies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Wenlong Yuan
Lucas M. Macri
Bradley M. Peterson
Adam G. Riess
Michael M. Fausnaugh
Samantha L. Hoffmann
Gagandeep S. Anand
Misty C. Bentz
Elena Dalla Bontà
Richard I. Davies
Gisella de Rosa
Laura Ferrarese
Catherine J. Grier
Erin K. S. Hicks
Christopher A. Onken
Richard W. Pogge
Thaisa Storchi-Bergmann
Marianne Vestergaard
摘要： We derive a distance of $D = 16.6 \pm 0.3$~Mpc ($\mu=31.10\pm0.04$~mag) to the archetypal narrow-line Seyfert 1 galaxy NGC 4051 based on Cepheid Period--Luminosity relations and new Hubble Space Telescope multiband imaging. We identify 419 Cepheid candidates and estimate the distance at both optical and near-infrared wavelengths using subsamples of precisely-photometered variables (123 and 47 in the optical and near-infrared subsamples, respectively). We compare our independent photometric procedures and distance-estimation methods to those used by the SH0ES team and find agreement to 0.01~mag. The distance we obtain suggests an Eddington ratio $\dot{m} \approx 0.2$ for NGC 4051, typical of narrow-line Seyfert 1 galaxies, unlike the seemingly-odd value implied by previous distance estimates. We derive a peculiar velocity of $-490\pm34$~km~s$^{-1}$ for NGC 4051, consistent with the overall motion of the Ursa Major Cluster in which it resides. We also revisit the energetics of the NGC 4051 nucleus, including its outflow and mass accretion rates.
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