Sasmirala Individual Information for NGC 4051

Description

NGC 4051 is a low-inclination grand-design spiral galaxy at a distance of D = 12.2 ± 2.4 Mpc [tully_extragalactic_2009] and belongs to the original six Seyfert galaxies [seyfert_nuclear_1943]. It contains a well-studied variable AGN (see [maitra_jet_2011] for a recent analysis if its SED), which is classified optically either as Sy 1n [veron-cetty_catalogue_2010] or Sy 1.2 [ho_search_1997-1]. It is a member of the nine-month BAT AGN sample. The nucleus has a complex radio morphology with a double/triple source with ~ 0.4arcsec separation in east-west direction [ulvestad_radio_1984, kukula_high-resolution_1995] and a very weak central unresolved source [giroletti_faintest_2009]. A weak extended NLR component coincides with the radio structure (diameter~ 1.2arcsec ~ 71 pc; PA~ 100∘; [schmitt_comparison_1996]). In addition, very weak water maser emission was detected in the nucleus with uncertain relation to the AGN [hagiwara_search_2003, hagiwara_low-luminosity_2007]. The first successful MIR observations were performed by [rieke_infrared_1972], followed by [rieke_infrared_1978] and [lebofsky_extinction_1979], [aitken_8-13_1985],[devereux_spatial_1987], [roche_atlas_1991]. The first subarcsecond-resolution N-band image was obtained with Palomar 5 m/MIRLIN in 2000 [gorjian_10_2004], where a point-like nucleus without host emission was detected. In addition, ISO (e.g., [ramos_almeida_mid-infrared_2007]) and Spitzer/IRAC, IRS and MIPS observations are available. In the IRAC 5.8 and 8.0 μm and MIPS 24 μm images, the compact nucleus completely dominates the MIR emission, while the host is only weakly visible. The latter becomes brighter towards longer wavelengths. Our nuclear IRAC 5.8 and 8.0 μm photometry is consistent with [gallimore_infrared_2010]. The IRS LR staring-mode spectrum exhibits weak silicate 10 and 18 μm emission, prominent PAH features, and a shallow emission peak at ~ 18μm in νFν-space (see also [buchanan_spitzer_2006, wu_spitzer/irs_2009, deo_mid-infrared_2009, goulding_towards_2009, tommasin_spitzer-irs_2010]). Note however that no background subtraction was performed for the long-wavelength part of the spectrum (> 14 μm). The presence of the PAH emission indicates that the arcsecond-scale MIR SED is affected by star formation. The Spitzer spectrophotometry is consistent with the MIRLIN flux but significantly higher than the historical measurements. We observed the nuclear region of NGC 4051 with Michelle in the Si-5 filter in 2010 and detected a possibly marginally resolved nucleus without any other host emission (FWHM ~ 0.44arcsec ~ 26 pc). However, the current data are not sufficient for a robust classification of the nuclear extension in the MIR at subarcsecond scales. The nuclear photometry is 21% lower than the Spitzer spectrophotometry. The current subarcsecond data are not sufficient to constrain the star formation contribution in the central ~ 25 pc.

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.

Photometry details and reduced FITS files

ObjectRA
[deg]		Dec
[deg]		FilterImageInfoλ_c
[um]		HWHM
[um]		InstrPix. size
[arcsec/pix]		T_exp
[s]		ModeChop Throw
[arcsec]		Chop Angle
[deg]		Rot
[deg]		Prog IdCal. StarCal. DateDate Obs.Factor
[mJy/ct]		Err. Factor
[mJy/ct]		Cal. Flux
[mJy]		Upper Lim. Gauss?F_Gauss
[mJy]		E(F_Gauss)
[mJy]		Upper Lim. PSF?F_PSF
[mJy]		E(F_PSF)
[mJy]		Cal. Maj.
[arcsec]		Cal. Min.
[arcsec]		Cal. PA.
[deg]		Maj. Ax
[arcsec]		Min. Ax
[arcsec]		Pos. Ang.
[deg]
NGC 4051180.79000044.531389Si-5NGC4051_Si-5_2010-02-02T11-37.fits[Details]11.60.55MICHELLE0.101156.0PARA15.00.00.0GN-2010A-C-7HD952122010-02-02T11:54:14Z2010-02-02T11:36:58Z1.021170.015285078.0False464.010.2False438.19.90.460.4151.00.470.42134.0