Sasmirala Individual Information for NGC 7743

Description

NGC 7743 is a low-inclination barred lenticular galaxy at a distance of D = 19.2 ± 1.6 Mpc [jensen_measuring_2003] with a borderline Sy 2/LINER nucleus [ho_reevaluation_1993, ho_search_1997-1, alonso-herrero_nature_2000]. At radio wavelengths, it appears as a compact source at arcsecond resolution [nagar_radio_1999, ho_radio_2001]. NGC 7743 was weakly detected with IRAS in the MIR and followed up with Spitzer/IRAC, IRS and MIPS observations. The corresponding IRAC and MIPS images show an extended nucleus embedded within elliptical diffuse host emission. The IRS LR staring-mode spectrum suffers from a very low S/N but indicates PAH emission and a red spectral slope in νF_ν-space. Thus, the arcsecond-scale MIR SED is significantly affected by star formation. We observed the nuclear region of NGC 7743 with VISIR in four narrow N-band filters in 2009 but failed to detect the nucleus (partly published in [asmus_mid-infrared_2011]). Owing to our optimized flux measurement method, we are able to derive more stringent flux upper limits than in the previous work. These are on average ~ 63% lower than the Spitzer spectrophotometry and thus indicate that the MIR emission of NGC 7743 is indeed dominated by star formation. Note, however, that [pereira-santaella_mid-infrared_2010] report the detection of AGN-indicative [Ne V] emission in the IRS spectrum.

• [alonso-herrero_nature_2000] Almudena Alonso-Herrero, Marcia J. Rieke, George H. Rieke, and Joseph C. Shields. The nature of LINERS . ApJ , 530 pp. 688–703, February 2000.
• [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.
• [ho_radio_2001] Luis C. Ho and James S. Ulvestad. Radio continuum survey of an optically selected sample of nearby seyfert galaxies . ApJS , 133 pp. 77–118, March 2001.
• [ho_reevaluation_1993] Luis C. Ho, Alexei V. Filippenko, and Wallace L. W. Sargent. A reevaluation of the excitation mechanism of LINERs . ApJ , 417 pp. 63, November 1993.
• [ho_search_1997-1] Luis C. Ho, Alexei V. Filippenko, and Wallace L. W. Sargent. A search for ``Dwarf'' seyfert nuclei. III. spectroscopic parameters and properties of the host galaxies . ApJS , 112 pp. 315, October 1997.
• [jensen_measuring_2003] Joseph B. Jensen, John L. Tonry, Brian J. Barris, Rodger I. Thompson, Michael C. Liu, Marcia J. Rieke, Edward A. Ajhar, and John P. Blakeslee. Measuring distances and probing the unresolved stellar populations of galaxies using infrared surface brightness fluctuations . ApJ , 583 pp. 712–726, February 2003.
• [nagar_radio_1999] Neil M. Nagar, Andrew S. Wilson, John S. Mulchaey, and Jack F. Gallimore. Radio structures of seyfert galaxies. VIII. a distance- and magnitude-limited sample of early-type galaxies . ApJS , 120 pp. 209–245, February 1999.
• [pereira-santaella_mid-infrared_2010] Miguel Pereira-Santaella, Aleksandar M. Diamond-Stanic, Almudena Alonso-Herrero, and George H. Rieke. The mid-infrared high-ionization lines from active galactic nuclei and star-forming galaxies . ApJ , 725 pp. 2270–2280, December 2010.

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.