Sasmirala Individual Information for NGC 424
Description
NGC 424 is an inclined spiral galaxy at a redshift of z = 0.0118 (D ~ 49.5 Mpc) with an AGN controversially classified as a Sy 1 [murayama_high-ionization_1998] or as Sy 2 [smith_emission-line_1975]. Broad emission lines are detected in polarized light [moran_frequency_2000]. The fact that the nucleus is highly obscured and probably even Compton-thick in X-rays favours the Sy 2 classification [collinge_compton-thick_2000]. The nucleus of NGC 424 is radio-quiet and unresolved [mundell_parsec-scale_2000]. After IRAS, NGC 424 was observed with Spitzer/IRAC, IRS and MIPS. It appears very compact in the IRAC and MIPS PBCD images but is saturated in the former. Therefore, the IRAC 5.8 and 8.0 μm data are not analysed (but see [gallimore_infrared_2010]). The IRS LR mapping mode spectrum exhibits silicate 10 and 18 μm emission and a blue spectral slope in νFν-space but no PAH 11.3 μm feature (see also [buchanan_spitzer_2006, tommasin_spitzer_2008, wu_spitzer/irs_2009, gallimore_infrared_2010, tommasin_spitzer-irs_2010]. Interestingly, the MIR SED thus resembles more that of an unobscured AGN. NGC 424 was observed with T-ReCS in the N filter in 2003 (unpublished, to our knowledge). An elongated nucleus was detected in the image (FWHM ~ 0.45arcsec ~ 106 pc; PA~ 80∘). However, this finding needs to be verified by at least another epoch of subarcsecond MIR imaging. The measured N filter flux is consistent with the Spitzer spectrophotometry, but it would be significantly lower if the presence of subarcsecond-extended emission can be verified. Note that the MIR nucleus of NGC 424 could be resolved with MIDI interferometric observations, where it shows an elongation along the polar direction of the system (diameter~ 4 pc; PA~ 153∘; [honig_parsec-scale_2012]).
- [buchanan_spitzer_2006] Catherine L. Buchanan, Jack F. Gallimore, Christopher P. O'Dea, Stefi A. Baum, David J. Axon, Andrew Robinson, Moshe Elitzur, and Martin Elvis. Spitzer IRS spectra of a large sample of seyfert galaxies: A variety of infrared spectral energy distributions in the local active galactic nucleus population . AJ , 132 pp. 401–419, July 2006.
- [collinge_compton-thick_2000] M. J. Collinge and W. N. Brandt. Compton-thick x-ray absorption in the seyfert galaxies tololo 0109-383 and ESO 138-g1 . MNRAS , 317 pp. L35–L39, September 2000.
- [gallimore_infrared_2010] J. F. Gallimore, A. Yzaguirre, J. Jakoboski, M. J. Stevenosky, D. J. Axon, S. A. Baum, C. L. Buchanan, M. Elitzur, M. Elvis, C. P. O'Dea, and A. Robinson. Infrared spectral energy distributions of seyfert galaxies: Spitzer space telescope observations of the 12 μm sample of active galaxies . ApJS , 187 pp. 172–211, March 2010.
- [honig_parsec-scale_2012] S. F. Hönig, M. Kishimoto, R. Antonucci, A. Marconi, M. A. Prieto, K. Tristram, and G. Weigelt. Parsec-scale dust emission from the polar region in the type 2 nucleus of NGC 424 . ApJ , 755 pp. 149, August 2012.
- [moran_frequency_2000] Edward C. Moran, Aaron J. Barth, Laura E. Kay, and Alexei V. Filippenko. The frequency of polarized broad emission lines in type 2 seyfert galaxies . ApJL , 540 pp. L73–L77, September 2000.
- [mundell_parsec-scale_2000] C. G. Mundell, A. S. Wilson, J. S. Ulvestad, and A. L. Roy. Parsec-scale images of flat-spectrum radio sources in seyfert galaxies . ApJ , 529 pp. 816–831, February 2000.
- [murayama_high-ionization_1998] Takashi Murayama, Yoshiaki Taniguchi, and Kazushi Iwasawa. High-ionization nuclear emission-line region in the seyfert galaxy tololo 0109-383 . AJ , 115 pp. 460, February 1998.
- [smith_emission-line_1975] M. G. Smith. Emission-line galaxies and quasars in the southern hemisphere. i - description and applications of an objective-prism survey . ApJ , 202 pp. 591–595, December 1975.
- [tommasin_spitzer-irs_2010] Silvia Tommasin, Luigi Spinoglio, Matthew A. Malkan, and Giovanni Fazio. Spitzer-IRS high-resolution spectroscopy of the 12 μm seyfert galaxies. II. results for the complete data set . ApJ , 709 pp. 1257–1283, February 2010.
- [tommasin_spitzer_2008] Silvia Tommasin, Luigi Spinoglio, Matthew A. Malkan, Howard Smith, Eduardo González-Alfonso, and Vassilis Charmandaris. Spitzer IRS high-resolution spectroscopy of the 12 μm seyfert galaxies. i. first results . ApJ , 676 pp. 836–856, April 2008.
- [wu_spitzer/irs_2009] Yanling Wu, Vassilis Charmandaris, Jiasheng Huang, Luigi Spinoglio, and Silvia Tommasin. Spitzer/IRS 5-35 μm low-resolution spectroscopy of the 12 μm seyfert sample . ApJ , 701 pp. 658–676, August 2009.
Images
Optical image (DSS, red filter). Displayed are the central 4 arcmin with North being up and East to the left. The colour scaling is linear with white corresponding to the median background (BG) and black to the 0.01% pixels with the highest intensity.
Spitzer MIR images. Displayed are the inner 40 arcsec with North being up and East to the left. The colour scaling is logarithmic with white corresponding to median BG and black to the 0.1% pixels with the highest intensity. The label in the bottom left states instrument and central wavelength of the filter in micron (I: IRAC, M: MIPS).
Subarcsecond-resolution MIR images sorted by increasing filter central wavelength. Displayed are the inner 4 arcsec with North being up and East to the left. The colour scaling is logarithmic with white corresponding to median BG and black to the 75% of the highest intensity of all images in units of sig_bg. The inset image (where present; either bottom or top right) shows the central arcsecond of the PSF from the calibrator star, scaled to match the science target. The labels in the bottom left state instrument and filter names (C: COMICS, M: Michelle, T: T-ReCS, V: VISIR).
SEDs
MIR SED. The description of the symbols in all the SED plots (where present) is the following: Grey crosses and solid lines mark the Spitzer/IRAC, MIPS and IRS data. The colour coding of the other symbols is as follows: green for COMICS, magenta for Michelle, blue for T-ReCS and red for VISIR data. Darker-coloured solid lines mark spectra of the corresponding instrument. The black filled circles mark the nuclear 12 and 18 micron continuum emission estimate from the data (where present). The ticks on the top axis mark positions of common MIR emission lines, while the light grey horizontal bars mark wavelength ranges affected by the silicate 10 and 18 micron features.