Sasmirala Individual Information for NGC 4941
Description
NGC 4941 is an inclined barred spiral galaxy at a distance of D = 21.2 ± 6.7 Mpc (NED redshift-independent median) with a Sy 2.0 nucleus [veron-cetty_catalogue_2010]. At radio wavelengths, a compact double source was detected, which in total extends for ~ 0.5arcsec ~ 50 pc along a PA~-25∘ [schmitt_jet_2001]. The [O III] emission is compact with a weak extended halo [pogge_circumnuclear_1989]. The first ground-based MIR observations were carried out with Palomar 5 m/MIRLIN in 2000 [gorjian_10_2004], in which a compact nucleus was detected. The Spitzer/IRAC and MIPS images show a compact nucleus surrounded by the lenticularly-formed host emission. Our nuclear IRAC 5.8 and 8.0 μm photometry is significantly lower than the values in [gallimore_infrared_2010]. The Spitzer/IRS LR staring-mode spectrum exhibits possible weak silicate 10 and 18 μm emission, very weak PAH features, prominent forbidden emission lines and a red spectral slope in νFν-space (see also [shi_9.7_2006, wu_spitzer/irs_2009, tommasin_spitzer-irs_2010, gallimore_infrared_2010]). This arcsecond-scale MIR SED, thus, indicates little star formation. We observed the nuclear region of NGC 4941 with VISIR in four narrow N and one Q band filter in 2006 [horst_mid_2008, horst_mid-infrared_2009], 2009 [asmus_mid-infrared_2011] and 2011. The corresponding images show an unresolved nucleus without any further host emission. Our reanalysis of the published images provides unchanged nuclear fluxes, while the subarcsecond photometry in general is consistent with the Spitzer spectrophotometry. Therefore, the MIR emission from the central ~ 0.4 kpc appears to be AGN-dominated.
- [asmus_mid-infrared_2011] D. Asmus, P. Gandhi, A. Smette, S. F. Hönig, and W. J. Duschl. Mid-infrared properties of nearby low-luminosity AGN at high angular resolution . A&A , 536 pp. 36, December 2011.
- [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.
- [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.
- [pogge_circumnuclear_1989] Richard W. Pogge. The circumnuclear environment of nearby, noninteracting seyfert galaxies . ApJ , 345 pp. 730–751, October 1989.
- [schmitt_jet_2001] H. R. Schmitt, J. S. Ulvestad, R. R. J. Antonucci, and A. L. Kinney. Jet directions in seyfert galaxies: Radio continuum imaging data . ApJS , 132 pp. 199–209, February 2001.
- [shi_9.7_2006] Y. Shi, G. H. Rieke, D. C. Hines, V. Gorjian, M. W. Werner, K. Cleary, F. J. Low, P. S. Smith, and J. Bouwman. 9.7 μm silicate features in active galactic nuclei: New insights into unification models . ApJ , 653 pp. 127–136, December 2006.
- [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
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.