Sasmirala Individual Information for NGC 4501
Description
NGC 4501 is an inclined spiral galaxy in the Virgo cluster at a distance of D = 17.9 ± 5.8 Mpc (NED redshift-independent median) that hosts a Sy 2 nucleus [veron-cetty_catalogue_2010]. The first unsuccessful attempts to detect the nucleus in the MIR were made by [rieke_10_1978] and [scoville_10_1983]. The first possible weak detection is reported by [maiolino_new_1995] with the MMT bolometer, while the nucleus again remained undetected in the first subarcsecond-resolution N-band imaging observation with Palomar 5 m/MIRLIN [gorjian_10_2004]. The Spitzer/IRAC images show an extended nucleus embedded in the spiral-like host emission, while the nucleus appears as a weak compact source in the MIPS 24 μm image. Because we measure the flux of the central four-arcsecond region, our 5.8 and 8.0 μm photometry is significantly lower than previously published values [gallimore_infrared_2010]. The IRS LR mapping-mode PBCD spectrum suffers from very low S/N and is probably not very reliable regarding the complex extended morphology of NGC 4501 in the MIR. However, it matches our IRAC and MIPS photometry and indicates weak silicate 10 μm absorption and PAH emission, i.e., star formation (see also [wu_spitzer/irs_2009, deo_mid-infrared_2009, gallimore_infrared_2010, tommasin_spitzer_2008]). The nucleus of NGC 4501 was observed with T-ReCS in the N filter in 2004 but has not been detected. We observed it with Michelle in 2010 in the Si-5 filter and find a very weak compact detection with a flux of only 23% of the Spitzer spectrophotometry. The low S/N prevents us to make any statement about the source extension. The fact that our derived upper limit from the T-ReCS observation gives a lower flux indicates silicate absorption in the projected central ~ 30 pc of NGC 4501, supporting the obscured scenario for its nucleus.
- [deo_mid-infrared_2009] Rajesh P. Deo, Gordon T. Richards, D. M. Crenshaw, and S. B. Kraemer. The mid-infrared continua of seyfert galaxies . ApJ , 705 pp. 14–31, November 2009.
- [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.
- [maiolino_new_1995] R. Maiolino, M. Ruiz, G. H. Rieke, and L. D. Keller. New constraints on the unified model of seyfert galaxies . ApJ , 446 pp. 561, June 1995.
- [rieke_10_1978] G. H. Rieke and M. J. Lebofsky. 10 micron observations of bright galaxies . ApJL , 220 pp. L37–L41, March 1978.
- [scoville_10_1983] N. Z. Scoville, E. E. Becklin, J. S. Young, and R. W. Capps. A 10 micron survey of star formation in galactic nuclei virgo spiral galaxies . ApJ , 271 pp. 512–523, August 1983.
- [tommasin_spitzer_2008] Silvia Tommasin, Luigi Spinoglio, Matthew A. Malkan, Howard Smith, Eduardo González-Alfonso, and Vassilis Charmandaris. Spitzer IRS high-resolution spectroscopy of the 12 μm seyfert galaxies. i. first results . ApJ , 676 pp. 836–856, April 2008.
- [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.