Sasmirala Individual Information for Mrk 520
Description
Mrk 520 is a peculiar galaxy at a redshift of z = 0.0266 (D ~ 115 Mpc) with wide tidal arms and a compact object (LEDA 200376) superimposed ~ 21arcsec to the south-east, which is most likely a star (see 2MASS images). Mrk 520 contains a little-studied Sy 1.9 nucleus [lonsdale_vlbi_1992] that belongs to nine-month BAT AGN sample. Furthermore, the nucleus is classified as an AGN/starburst composite by [winter_optical_2010], and we adopt this classification. It appears extended at radio wavelengths on kiloparsec scales, mainly in the north-south directions [lonsdale_vlbi_1992]. Mrk 520 was first detected in the MIR with IRAS and followed up with ISO [dennefeld_iso_2003] and Spitzer/IRS. The corresponding IRS LR staring-mode spectrum is dominated by PAH emission with silicate 10 μm absorption and a red spectral slope in νFν-space (see also [sargsyan_infrared_2011]). Thus, the arcsecond-scale MIR SED appears to be star-formation dominated but the detection of strong [Ne V] emission points at the existence of a powerful AGN in Mrk 520 as well. We observed Mrk 520 with VISIR in three narrow N-band filters in 2009 and detected a possibly marginally resolved nucleus (FWHM ~ 0.43arcsec ~ 230 pc). However, at least another epoch of subarcsecond MIR imaging is required to verify this extension. The nuclear VISIR photometry is on average ~ 43% lower than the Spitzer spectrophotometry and indicates that at least part of the star-formation emission is excluded at subarcsecond resolution.
- [dennefeld_iso_2003] M. Dennefeld, T. Boller, D. Rigopoulou, and H. W. W. Spoon. ISO observations of four active galaxies . A&A , 406 pp. 527–534, August 2003.
- [lonsdale_vlbi_1992] Colin J. Lonsdale, Carol J. Lonsdale, and Harding E. Smith. A VLBI search for AGN radio cores in starburst galaxies . ApJ , 391 pp. 629–650, June 1992.
- [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.
- [winter_optical_2010] Lisa M. Winter, Karen T. Lewis, Michael Koss, Sylvain Veilleux, Brian Keeney, and Richard F. Mushotzky. Optical spectral properties of swift burst alert telescope hard x-ray-selected active galactic nuclei sources . ApJ , 710 pp. 503–539, February 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.