A Hard Look at NGC 5347: Revealing a Nearby Compton-thick AGN Article uri icon

Authors

  • Kammoun, E. S., Miller, J. M., Zoghbi, A., Oh, K., Koss, M., Mushotzky, R. F., Brenneman, Laura W., Brandt, W. N., Proga, D., Lohfink, A. M., Kaastra, J. S., Barret, D., Behar, E. and Stern, D.

abstract

  • Current measurements show that the observed fraction of Compton-thick (CT) active galactic nuclei (AGN) is smaller than the expected values needed to explain the cosmic X-ray background. Prior fits to the X-ray spectrum of the nearby Seyfert-2 galaxy NGC 5347 (z = 0.00792, D = 35.5 Mpc ) have alternately suggested a CT and Compton-thin source. Combining archival data from Suzaku, Chandra, and—most importantly—new data from NuSTAR, and using three distinct families of models, we show that NGC 5347 is an obscured CTAGN (N H > 2.23 × 1024 cm-2). Its 2–30 keV spectrum is dominated by reprocessed emission from distant material, characterized by a strong Fe Ka line and a Compton hump. We found a large equivalent width of the Fe Ka line (EW = 2.3 ± 0.3 keV) and a high intrinsic-to-observed flux ratio (~100). All of these observations are typical for bona fide CTAGN. We estimate a bolometric luminosity of L bol ? 0.014 ± 0.005 L Edd.. The Chandra image of NGC 5347 reveals the presence of extended emission dominating the soft X-ray spectrum (E < 2 keV), which coincides with the [O III] emission detected in Hubble Space Telescope images. Comparison to other CTAGN suggests that NGC 5347 is broadly consistent with the average properties of this source class. We simulated XRISM and Athena/X-IFU spectra of the source, showing the potential of these future missions in identifying CTAGN in the soft X-rays.

publication date

  • 2020