Sasmirala Individual Information for NGC 4636

Description

NGC 4636 is one of the X-ray brightest elliptical galaxies in the Virgo cluster at a distance of D = 15.6 ± 2.7 Mpc (NED redshift-independent median). It hosts a broad-line LINER [ho_search_1997-1]. An X-ray point source consistent with the nuclear position is present, but appears very weakly and with a soft spectrum, which disfavours an AGN unless highly obscured [gonzalez-martin_x-ray_2006, gonzalez-martin_fitting_2009, flohic_central_2006, baldi_unusual_2009]. In addition, NGC 4636 features a weak compact radio source with kiloparsec-scale jet-like bicones (PA~ 40; [birkinshaw_orientations_1985, stanger_high-resolution_1986, nagar_radio_2000]). The NLR has a compact and a wide outflow component, extending ~ 3arcsec ~ 220 pc towards the north (e.g., [masegosa_nature_2011]). The first ground-based MIR observations of NGC 4636 were performed by [impey_infrared_1986] and [devereux_infrared_1987], but the nucleus remained undetected. In addition, ISO [ferrari_survey_2002, athey_mid-infrared_2002, temi_cold_2004, temi_ages_2005] and Spitzer/IRAC, IRS and MIPS observed this object. The corresponding IRAC and MIPS images show extended host emission without any separable nuclear component. Our unresolved nuclear MIPS 24 μm flux measurement, therefore, provides a significantly lower value than the total flux given in [temi_spitzer_2009]. The IRS LR staring-mode spectrum shows weak silicate 10 and 18 μm emission and a blue spectral slope in νFν-space but no PAH features, typical for an inactive elliptical (see also [bressan_spitzer_2006]). The nuclear region of NGC 4636 was observed with VISIR in the PAH2_2 during three nights in 2010, but nothing was detected (unpublished, to our knowledge). All derived flux upper limits are higher than the Spitzer spectrophotometry, which we, therefore, use to derive an upper limit on the 12 μm continuum emission of any AGN in NGC 4636.

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).

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 4636190.7075002.687778PAH2_2[Details]11.880.37VISIR0.075905.0PERP8.00.00.0384.B-0943(A)HD834252010-02-23T04:33:36Z2010-02-23T04:13:26Z0.022920.000777519.3True16.3N/ATrue16.3N/A0.40.3413.0N/AN/AN/A
NGC 4636190.7075002.687778PAH2_2[Details]11.880.37VISIR0.075906.0PERP8.00.00.0384.B-0943(A)HD1231232010-03-24T05:31:12Z2010-03-24T05:51:22Z0.023550.000216165.3True28.6N/ATrue28.6N/A0.560.5195.0N/AN/AN/A
NGC 4636190.7075002.687778PAH2_2[Details]11.880.37VISIR0.075903.0PERP8.00.00.0384.B-0943(A)HD991672010-04-01T04:52:19Z2010-04-01T04:58:05Z0.020280.0001912980.6True7.9N/ATrue7.9N/A0.320.31171.0N/AN/AN/A