Sasmirala Individual Information for NGC 454E
Description
NGC 454 is a strongly interacting system of two galaxies (nuclei separation~ 28arcsec ~ 7 kpc; PA~ 70∘; [johansson_activity_1988]) at a redshift of z = 0.0122 (D ~ 52.3 Mpc). The eastern component, NGC 454E, is elliptical, more regular and brighter than the western starburst component. NGC 454E hosts a Sy 2 nucleus [veron-cetty_catalogue_2010] that belongs to the nine-month BAT AGN sample. Its X-ray obscuration was observed to change significantly [marchese_ngc_2012]. After IRAS, NGC 454E was observed with Spitzer/IRS in LR staring mode. The spectrum exhibits a flat spectral slope in νFν-space, silicate 10 μm absorption and PAH 11.3 μm emission, i.e., significant star formation (see also [weaver_mid-infrared_2010, sargsyan_infrared_2011]). The interacting system is resolved in the WISE images with NGC 454E dominating the MIR emission in all bands. NGC 454W appears bow-like with a bright compact source at the closest point to NGC 454E (PA~ 245∘; distance ~ 0.5arcmimin ~ 7 kpc). We observed NGC 454E with VISIR in three narrow N-band filters in 2009 and detected an elongated MIR nucleus in all cases (FWHM ~ 0.43arcsec ~ 107 pc; PA~ 120∘). However, at least a second epoch of subarcsecond MIR imaging is required to verify this extension. The nuclear VISIR photometry is in general consistent with the IRS spectrum but with less PAH 11 μm emission indicating a lower star formation contribution towards the MIR emission of the projected central ~ 100 pc of NGC 454E. Note that the nuclear fluxes would be significantly lower if the presence of subarcsecond-extended emission can be verified.
- [johansson_activity_1988] L. Johansson. Activity in the central parts of interacting galaxies - the starburst galaxy NGC 454 . A&A , 191 pp. 29–38, February 1988.
- [marchese_ngc_2012] E. Marchese, V. Braito, R. Della Ceca, A. Caccianiga, and P. Severgnini. NGC 454: unveiling a new 'changing look' active galactic nucleus . MNRAS , 421 pp. 1803–1812, April 2012.
- [sargsyan_infrared_2011] Lusine Sargsyan, Daniel Weedman, Vianney Lebouteiller, James Houck, Donald Barry, Ashot Hovhannisyan, and Areg Mickaelian. Infrared spectra and spectral energy distributions for dusty starbursts and active galactic nuclei . ApJ , 730 pp. 19, March 2011.
- [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.
- [weaver_mid-infrared_2010] K. A. Weaver, M. Meléndez, R. F. Mushotzky, S. Kraemer, K. Engle, E. Malumuth, J. Tueller, C. Markwardt, C. T. Berghea, R. P. Dudik, L. M. Winter, and L. Armus. Mid-infrared properties of the swift burst alert telescope active galactic nuclei sample of the local universe. i. emission-line diagnostics . ApJ , 716 pp. 1151–1165, June 2010.
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.
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.