Sasmirala Individual Information for NGC 5995

Description

NGC 5995 is an inclined barred spiral galaxy at a redshift of z = 0.0252 (D ~117 Mpc) with a Sy 1.9 nucleus [veron-cetty_catalogue_2010], which was detected as a compact radio source [thean_high-resolution_2000]. After its detection in IRAS, this object was followed up with Palomar 5 m/MIRLIN [gorjian_10_2004] and ESO 3.6 m/TIMMI2 [galliano_mid-infrared_2005]. An unresolved nucleus at arcsecond resolution was detected in both data sets. The Spitzer/IRAC and MIPS images are also dominated by a compact nucleus without significant host emission. Our corresponding nuclear IRAC 5.8 μm photometry agrees with [gallimore_infrared_2010], while our IRAC 8.0 μm flux is ~ 30% lower than published by these authors. In comparison, our fluxes are consistent with the Spitzer/IRS spectrum. Not surprisingly, our MIPS 24 μm flux is significantly higher than the star-formation subtracted nuclear flux from [shi_unobscured_2010]. The Spitzer/IRS LR mapping-mode spectrum exhibits silicate 10 μm absorption, PAH emission and a flat spectral slope in νF_ν-space (see also [wu_spitzer/irs_2009, tommasin_spitzer-irs_2010, shi_unobscured_2010, gallimore_infrared_2010]). Thus, the arcsecond-scale MIR SED seems to be affected by star formation. We observed the nuclear region of NGC 5995 with VISIR in three narrow N-band filters in 2006 [horst_mid_2008, horst_mid-infrared_2009] and another two in 2010 (unpublished, to our knowledge), and also obtained a LR N-band spectrum in 2009 [honig_dusty_2010-1]. A compact MIR nucleus was detected in all images, and the diffraction-limited high-S/N images from 2010 show that the nucleus is unresolved, which has not been clear form the 2006 images. Our nuclear photometry is consistent with the previously published values, yet systematically higher by ~ 10% compared to the VISIR spectrum. However, this offset is well within the calibration uncertainties. The corresponding nuclear MIR SED has on average ~ 13% lower flux levels than the arcsecond-scale MIR SED as traced by Spitzer, while exhibiting the same silicate 10 μm absorption and much weaker PAH emission. Therefore, we conclude that the silicate feature is generic to the (projected) central ~ 200 pc of NGC 5995, and star-formation contribution towards the nuclear MIR SED is presumably very low. The nuclear MIR emission of NGC 5995 could be resolved with MIDI interferometric observations and was modelled as two approximately equally bright components, one extending for ~ 20 pc, and the other one remaining unresolved (< 5 pc; [burtscher_diversity_2013]).

• [burtscher_diversity_2013] L. Burtscher, K. Meisenheimer, K. R. W. Tristram, W. Jaffe, S. F. Hönig, R. I. Davies, M. Kishimoto, J.-U. Pott, H. Röttgering, M. Schartmann, G. Weigelt, and S. Wolf. A diversity of dusty AGN tori. data release for the VLTI/MIDI AGN large program and first results for 23 galaxies . A&A , 558 pp. 149, October 2013.
• [galliano_mid-infrared_2005] E. Galliano, D. Alloin, E. Pantin, P. O. Lagage, and O. Marco. Mid-infrared imaging of active galaxies. active nuclei and embedded star clusters . A&A , 438 pp. 803–820, August 2005.
• [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.
• [gorjian_10_2004] V. Gorjian, M. W. Werner, T. H. Jarrett, D. M. Cole, and M. E. Ressler. 10 micron imaging of seyfert galaxies from the 12 micron sample . ApJ , 605 pp. 156–167, April 2004.
• [honig_dusty_2010-1] S. F. Hönig, M. Kishimoto, P. Gandhi, A. Smette, D. Asmus, W. Duschl, M. Polletta, and G. Weigelt. The dusty heart of nearby active galaxies. i. high-spatial resolution mid-IR spectro-photometry of seyfert galaxies . A&A , 515 pp. 23, June 2010.
• [horst_mid-infrared_2009] H. Horst, W. J. Duschl, P. Gandhi, and A. Smette. Mid-infrared imaging of 25 local AGN with VLT-VISIR . A&A , 495 pp. 137–146, February 2009.
• [horst_mid_2008] H. Horst, P. Gandhi, A. Smette, and W. J. Duschl. The mid IR - hard x-ray correlation in AGN and its implications for dusty torus models . A&A , 479 pp. 389–396, February 2008.
• [shi_unobscured_2010] Yong Shi, George H. Rieke, Paul Smith, Jane Rigby, Dean Hines, Jennifer Donley, Gary Schmidt, and Aleksandar M. Diamond-Stanic. Unobscured type 2 active galactic nuclei . ApJ , 714 pp. 115–129, May 2010.
• [thean_high-resolution_2000] Andy Thean, Alan Pedlar, Marek J. Kukula, Stefi A. Baum, and Christopher P. O'Dea. High-resolution radio observations of seyfert galaxies in the extended 12-μm sample - i. the observations . MNRAS , 314 pp. 573–588, May 2000.
• [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.
• [veron-cetty_catalogue_2010] M.-P. Véron-Cetty and P. Véron. A catalogue of quasars and active nuclei: 13th edition . A&A , 518 pp. 10, July 2010.
• [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

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.