Sasmirala Individual Information for NGC 1275

Description

NGC 1275 is an infrared-luminous, radio-loud peculiar giant elliptical galaxy at a redshift of z = 0.0175 (D ~ 72.7 Mpc) with a FR I radio morphology and prominent galactic-scale gas filaments. This well-studied object is the central galaxy in the Perseus cluster and one of the original six Seyfert galaxies ([seyfert_nuclear_1943]; see [scharwachter_kinematics_2013] for a recent detailed study). It is presumably in a post-merger state [holtzman_planetary_1992, conselice_nature_2001] and features complex optical spectral properties, leading to many different classifications like Sy 2, borderline Sy 1.5/LINER, BL Lac and even Sy/H II composite [khachikian_atlas_1974, ho_search_1997, veron_ngc1275_1978, veron_agns_1997]. The nucleus is a compact source with a flat spectrum at radio wavelengths, and a pair of galactic-scale jets emerge from it with a PA~ 160 in the central kiloparsec region [pedlar_radio_1990, walker_detection_1994, vermeulen_discovery_1994]. Pioneering MIR observations of NGC 1275 were performed by [low_proceedings_1968] and [kleinmann_observations_1970], followed by [rieke_variability_1972, rieke_infrared_1978], [lebofsky_extinction_1979], [aitken_question_1981], [malkan_stellar_1983], [gear_thermal_1985], and [roche_atlas_1991]. The first subarcsecond-resolution N-band image obtained with Keck/LWS show an unresolved nucleus without any extended emission [soifer_high_2003]. NGC 1275 was also observed with ISO [rigopoulou_large_1999, tran_isocam-cvf_2001, siebenmorgen_isocam_2004, temi_cold_2004] and Spitzer/IRAC, IRS and MIPS in the MIR. The corresponding IRAC and MIPS images are dominated by a bright compact nucleus. The IRS LR staring-mode spectrum exhibits silicate 10 and 18 μm emission, a very weak PAH 11.3 μm features and a steep red spectral slope in νFν-space (see also [weedman_mid-infrared_2005, shi_aromatic_2007, leipski_spitzer_2009, mullaney_defining_2011]). Thus, the arcsecond-scale MIR SED verifies the existence of large amounts of AGN-heated dust in NGC 1275, while any star-formation contribution is at least minor [leipski_spitzer_2009]. NGC 1275 was observed with Michelle in the Si-2 and Si-6 filters in 2006 and with COMICS in the N11.7 and NEII filters in 2009 (unpublished, to our knowledge). A bright compact nucleus without further host emission was detected in all images. It appears to be marginally resolved in the sharpest image (Si-2) but displays inconsistent nuclear shapes between the Michelle and COMICS images. Therefore, its MIR extension at subarcsecond resolution remains uncertain. Our nuclear photometry is generally consistent with the Spitzer spectrophotometry with the Michelle fluxes being systematically lower and the COMICS flux systematically higher. We use the IRS spectrum to compute the nuclear 12 μm continuum emission estimate corrected for the silicate feature. Comparison with the historical N-band photometry shows apparent flux variations on the order of ~ 16% during the last ~ 40 years. This indicates intrinsic variability in the N-band emission of NGC 1275 despite uncertainties and systematics of the different instruments, filters and measurement methods.

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 127549.95083341.511667N11.7NGC1275_N11.7_2009-07-14T14-56.fits[Details]11.740.53COMICS0.133401.0PERP10.00.090.0o09108HD184492009-07-14T15:28:48Z2009-07-14T14:57:07Z0.14030.004884560.7False918.754.0False534.055.30.650.484.00.730.6269.0
NGC 127549.95083341.511667NeIINGC1275_NeII_2009-07-14T15-08.fits[Details]12.810.1COMICS0.133401.0PERP10.00.090.0o09108HD184492009-07-14T15:21:36Z2009-07-14T15:08:38Z1.367820.031325297.3False1208.460.9False1346.2114.81.00.86103.01.00.7671.0
NGC 127549.95083341.511667Si-2NGC1275_Si-2_2006-09-10T11-23.fits[Details]8.80.45MICHELLE0.101415.0PARA10.00.00.0GN-2006B-Q-19HD196562006-09-10T11:09:36Z2006-09-10T11:24:00Z1.17120.012587422.0False313.64.7False242.84.20.360.3239.00.430.3526.0
NGC 127549.95083341.511667Si-6NGC1275_Si-6_2006-09-10T11-49.fits[Details]12.50.6MICHELLE0.101376.0PARA10.00.00.0GN-2006B-Q-19HD196562006-09-10T11:09:36Z2006-09-10T11:48:29Z1.276190.011834027.0False886.411.4False892.711.40.420.3849.00.430.3726.0