Sasmirala Individual Information for NGC 5548

Description

NGC 5548 is a face-on spiral galaxy at a redshift of z = 0.0172 (D ~ 80.7 Mpc) with a well-studied Sy 1.5 nucleus [veron-cetty_catalogue_2010]. It is highly variable in optical and X-rays (e.g. [peterson_steps_2002]) and belongs to the nine-month BAT AGN sample. A compact radio-core with biconical structure was detected along a PA~ 160 and ~ 15arcsec extent [wilson_radio_1982-1, ho_radio_2001]. The [O III] emission extends to kiloparsec scales in north-south direction, roughly aligned with the radio emission [wilson_kinematics_1989, schmitt_hubble_2003]. The first MIR observation of NGC 5548 were carried out by [kleinmann_infrared_1970], followed by [rieke_infrared_1972, rieke_infrared_1978], and [ward_continuum_1987]. A first subarcsecond-resolution image was obtained with Palomar 5 m/MIRLIN in 2000 [gorjian_10_2004]. NGC 5548 was also observed with ISO [clavel_2.5-11_2000, ramos_almeida_mid-infrared_2007] and Spitzer/IRAC, IRS and MIPS. The corresponding IRAC and MIPS images are dominated by a bright nuclear source, with the extended host emission being faintly visible in the 5.8 and 8.μm images. Our nuclear IRAC 5.8 and 8.μm photometry is consistent with [gallimore_infrared_2010]. The IRS LR staring-mode spectrum shows silicate 10 and 18 μm emission, a prominent PAH 11.3 μm feature, and an emission peak at ~ 17 μm in νFν-space (see also [buchanan_spitzer_2006, shi_9.7_2006, wu_spitzer/irs_2009, tommasin_spitzer-irs_2010, gallimore_infrared_2010]). Thus, the arcsecond-scale MIR SED appears to be AGN-dominated. The nuclear region of NGC 5548 was observed with VISIR in two narrow N-band filters in 2010 [kishimoto_mapping_2011]. The nucleus appears to be elongated in north-south direction in both images. However, they were taken at a high airmass without matched standard star observations. Therefore, at least another epoch of MIR subarcsecond imaging under good ambient conditions is required to verify this extension, so that we classify the nucleus as possibly extended. Owing to this possible extension, the corresponding nuclear VISIR photometry is very uncertain and ~ 43% lower than the Spitzer spectrophotometry. In addition, all nuclear N-band flux measurements over the last ~ 40 years are consistent with no flux variations within the uncertainties. The only exception is the MIRLIN N flux, which is higher than the long-term average.

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 5548214.49791725.136667ARIIINGC5548_ARIII_2010-06-27T00-55.fits[Details]8.990.14VISIR0.075177.0PARA8.00.00.0085.B-0251(C)HD1242942010-06-27T00:23:02Z2010-06-27T00:56:10Z0.058270.0011619510.7False132.816.7False27.316.50.350.3114.00.810.6537.0
NGC 5548214.49791725.136667PAH2_2NGC5548_PAH2_2_2010-06-27T01-00.fits[Details]11.880.37VISIR0.075181.0PARA8.00.00.0085.B-0251(C)HD1242942010-06-27T00:33:07Z2010-06-27T01:00:29Z0.021930.0008411815.8False169.749.1False77.98.10.410.3714.00.660.514.0