Sasmirala Individual Information for NGC 3486

Description

NGC 3486 is a face-on spiral galaxy at a distance of D = 13.7 ± 2.7 Mpc [tully_extragalactic_2009] with a borderline Sy 2.0/LINER nucleus, which might be powered by a compact central star cluster instead of an accreting SMBH [maoz_low-luminosity_2007]. It has not been detected at radio wavelengths [ho_detection_2001] but in the X-rays, where it appears rather heavily absorbed [brightman_nature_2008]. The first attempt to detect NGC 3486 in the MIR failed [rieke_10_1978]. After its detection in IRAS, this object was also observed with Spitzer/IRAC, IRS and MIPS and appears as a compact nucleus embedded in bright ring-like host emission in the corresponding images. This ring-like emission dominates in the MIPS 24 μm image. The nucleus is extended in the IRAC images, and we measure only the central four-arcsecond region, which results in much lower fluxes than published for the total emission [dale_spitzer_2009]. The IRS LR staring-mode spectrum has a very low S/N and does not allow us to identify any spectral features. The general Spitzer spectrophotometry indicates a blue SED dominated by old stellar emission. We observed then nuclear region of NGC 3486 with Michelle in two N-band filters in 2010 but nothing was detected in the images. The derived flux upper limits are consistent with the Spitzer spectrophotometry. Thus, we can only conclude that the MIR emission of the central ~ 250 pc in NGC 3486 is dominated by diffuse stellar emission.

• [brightman_nature_2008] Murray Brightman and Kirpal Nandra. On the nature of unabsorbed seyfert 2 galaxies . MNRAS , 390 pp. 1241–1249, November 2008.
• [dale_spitzer_2009] D. A. Dale, J. D. T. Smith, E. A. Schlawin, L. Armus, B. A. Buckalew, S. A. Cohen, G. Helou, T. H. Jarrett, L. C. Johnson, J. Moustakas, E. J. Murphy, H. Roussel, K. Sheth, S. Staudaher, C. Bot, D. Calzetti, C. W. Engelbracht, K. D. Gordon, D. J. Hollenbach, R. C. Kennicutt, and S. Malhotra. The spitzer infrared nearby galaxies survey: A high-resolution spectroscopy anthology . ApJ , 693 pp. 1821–1834, March 2009.
• [ho_detection_2001] Luis C. Ho, Eric D. Feigelson, Leisa K. Townsley, Rita M. Sambruna, Gordon P. Garmire, W. N. Brandt, Alexei V. Filippenko, Richard E. Griffiths, Andrew F. Ptak, and Wallace L. W. Sargent. Detection of nuclear x-ray sources in nearby galaxies with chandra . ApJ , 549 pp. L51–L54, March 2001.
• [maoz_low-luminosity_2007] Dan Maoz. Low-luminosity active galactic nuclei: are they UV faint and radio loud? . MNRAS , 377 pp. 1696–1710, June 2007.
• [rieke_10_1978] G. H. Rieke and M. J. Lebofsky. 10 micron observations of bright galaxies . ApJL , 220 pp. L37–L41, March 1978.
• [tully_extragalactic_2009] R. Brent Tully, Luca Rizzi, Edward J. Shaya, Hélène M. Courtois, Dmitry I. Makarov, and Bradley A. Jacobs. The extragalactic distance database . AJ , 138 pp. 323–331, 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.