NGC 7552 is an infrared-luminous, nearly face-on, barred spiral galaxy at a redshift of z = 0.0054 (D ~ 20.4 Mpc) with a possibe active nucleus surrounded by a powerful circum-nuclear starburst ring (diameter~ 5arcsec ~ 0.5 kpc; [forbes_nuclear_1994, forbes_ngc_1994]; see [pan_formation_2013, brandl_high_2012] for recent detailed studies). The nucleus has been optically classified as a LINER [durret_imaging_1987] or H II [yuan_role_2010]. The presence of an AGN is supported by the detection of a compact nuclear source in hard X-rays [grier_discovery_2011, brightman_xmm-newton_2011]. However, we conservatively treat NGC 7552 as an uncertain AGN. Initial MIR observations of NGC 7552 are reported in [kleinmann_10-micron_1974], followed by many ground-based observations [frogel_8-13_1982, phillips_8-13_1984, roche_atlas_1991, schinnerer_circumnuclear_1997, siebenmorgen_mid-infrared_2004]. The latter two works present the first subarcsecond-resolution MIR images, which resolve the starburst ring as a clumpy structure. NGC 7552 was also observed with the space-based ISO [rigopoulou_large_1999, roussel_atlas_2001, verma_mid-infrared_2003] and Spitzer/IRAC, IRS and MIPS. The corresponding IRAC and MIPS images do not completely resolve the starburst ring, which appears as a dominating central source embedded within the spiral-like host galaxy emission (see also [brandl_high_2012]). We measure the nuclear flux component in the non-saturated IRAC 5.8 μm and MIPS 24 μm post-BCD images, which conclusively results in significantly lower values than in the literature (e.g. [dale_infrared_2005, munoz-mateos_radial_2009]). The IRS LR mapping-mode spectrum shows strong PAH emission and possibly weak silicate 10 μm absorption with a red spectral slope in νFν-space (see also [smith_mid-infrared_2007, marble_aromatic_2010]). As expected, the arcsecond-scale MIR SED appears to be star-formation dominated. The nuclear region of NGC 7552 was imaged with VISIR in eleven N-band and one Q-band filters in 2005 (partly published in [brandl_high_2012]). At least the brightest knots of the starburst ring are detected in all images, while the nucleus remains undetected (see [brandl_high_2012] for the analysis of the ring). A compact source is faintly visible at the nuclear position (< 2σ) only in the longest-wavelength N-band filters. Therefore, we determine flux upper limits on the nuclear emission, which are on average ~ 94% lower than the Spitzer spectrophotometry. We conclude that a very weak AGN might be present in NGC 7552 but star formation is dominating its MIR emission completely.
Object | RA [deg] | Dec [deg] | Filter | Image | Info | λ_c [um] | HWHM [um] | Instr | Pix. size [arcsec/pix] | T_exp [s] | Mode | Chop Throw [arcsec] | Chop Angle [deg] | Rot [deg] | Prog Id | Cal. Star | Cal. Date | Date 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 7552 | 349.045000 | -42.584722 | SIV_2 | [Details] | 10.77 | 0.19 | VISIR | 0.127 | 350.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD216032 | 2005-06-23T10:33:36Z | 2005-06-23T09:44:38Z | 0.35463 | 0.00629 | 31594.6 | True | 37.9 | N/A | True | 37.9 | N/A | 0.41 | 0.39 | 42.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | ARIII | [Details] | 8.99 | 0.14 | VISIR | 0.127 | 180.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD218670 | 2005-06-10T10:19:12Z | 2005-06-10T09:41:46Z | 0.06241 | 0.00109 | 10520.5 | True | 30.8 | N/A | True | 30.8 | N/A | 0.45 | 0.4 | 145.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | NEII | [Details] | 12.81 | 0.21 | VISIR | 0.127 | 508.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD216032 | 2005-06-23T10:40:48Z | 2005-06-23T08:32:38Z | 0.58117 | 0.01027 | 24005.5 | True | 77.7 | N/A | True | 77.7 | N/A | 0.43 | 0.41 | 30.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | NEII_1 | [Details] | 12.27 | 0.18 | VISIR | 0.127 | 690.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD216032 | 2005-06-23T10:40:48Z | 2005-06-23T08:15:22Z | 0.53967 | 0.00675 | 25149.9 | True | 43.9 | N/A | True | 43.9 | N/A | 0.44 | 0.42 | 64.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | NEII_2 | [Details] | 13.04 | 0.22 | VISIR | 0.127 | 1035.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD216032 | 2005-06-23T10:48:00Z | 2005-06-23T08:44:10Z | 0.57335 | 0.01153 | 23184.7 | True | 49.1 | N/A | True | 49.1 | N/A | 0.4 | 0.39 | 21.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | PAH1 | [Details] | 8.59 | 0.42 | VISIR | 0.127 | 173.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD218670 | 2005-06-10T10:13:26Z | 2005-06-10T09:37:26Z | 0.18857 | 0.00214 | 11414.2 | True | 35.0 | N/A | True | 35.0 | N/A | 0.47 | 0.43 | 148.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | PAH2 | [Details] | 11.25 | 0.59 | VISIR | 0.127 | 538.0 | PARA | 14.0 | 0.0 | 0.0 | 075.B-0727(A) | HD209688 | 2005-06-15T10:24:58Z | 2005-06-15T07:42:14Z | 0.1564 | 0.00754 | 9155.1 | True | 57.5 | N/A | True | 57.5 | N/A | 0.66 | 0.59 | 18.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | PAH2_2 | [Details] | 11.88 | 0.37 | VISIR | 0.127 | 538.0 | PARA | 14.0 | 0.0 | 0.0 | 075.B-0727(A) | HD196171 | 2005-06-15T06:38:53Z | 2005-06-15T07:55:12Z | 0.3997 | 0.06002 | 13649.6 | True | 60.2 | N/A | True | 60.2 | N/A | 0.56 | 0.47 | 156.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | Q2 | [Details] | 18.72 | 0.88 | VISIR | 0.127 | 3638.0 | PARA | 11.0 | 0.0 | 0.0 | 076.B-0656(A) | HD218670 | 2005-10-09T00:14:24Z | 2005-10-09T00:37:26Z | 0.47506 | 0.01707 | 2701.6 | True | 103.3 | N/A | True | 103.3 | N/A | 0.55 | 0.52 | 120.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | SIC | [Details] | 11.85 | 2.34 | VISIR | 0.127 | 362.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD218670 | 2005-06-10T10:24:58Z | 2005-06-10T09:51:50Z | 0.06764 | 0.00224 | 6803.1 | True | 45.1 | N/A | True | 45.1 | N/A | 0.49 | 0.43 | 152.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | SIV | [Details] | 10.49 | 0.16 | VISIR | 0.127 | 362.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD218670 | 2005-06-10T10:24:58Z | 2005-06-10T09:47:31Z | 0.05893 | 0.00115 | 8249.9 | True | 45.4 | N/A | True | 45.4 | N/A | 0.5 | 0.45 | 143.0 | N/A | N/A | N/A | |
NGC 7552 | 349.045000 | -42.584722 | SIV_1 | [Details] | 9.82 | 0.18 | VISIR | 0.127 | 2870.0 | PARA | 10.0 | 0.0 | 0.0 | 075.B-0182(A) | HD216032 | 2005-06-23T10:30:43Z | 2005-06-23T09:12:58Z | 0.64205 | 0.00816 | 37130.8 | True | 29.8 | N/A | True | 29.8 | N/A | 0.41 | 0.38 | 156.0 | N/A | N/A | N/A |