SIMBAD references

2007MNRAS.374..979C - Mon. Not. R. Astron. Soc., 374, 979-998 (2007/January-3)

Absolute diffuse calibration of IRAC through mid-infrared and radio study of HII regions.

COHEN M., GREEN A.J., MEADE M.R., BABLER B., INDEBETOUW R., WHITNEY B.A., WATSON C., WOLFIRE M., WOLFF M.J., MATHIS J.S. and CHURCHWELL E.B.

Abstract (from CDS):

We investigate the diffuse absolute calibration of the Infrared Array Camera (IRAC) on the Spitzer Space Telescope (SST) at 8.0µm using a sample of 43 Hii regions with a wide range of morphologies near l = 312°. For each region we carefully measure sky-subtracted, point-source-subtracted, areally integrated IRAC 8.0-µm fluxes and compare these with Midcourse Space eXperiment (MSX) 8.3-µm images at two different spatial resolutions, and with radio continuum maps. We determine an accurate median ratio of IRAC8.0-µm/MSX8.3-µm fluxes, of 1.55 ±0.15. From robust spectral energy distributions of these regions we conclude that the present 8.0-µm diffuse calibration of the SST is 36 per cent too high compared with the MSX validated calibration, perhaps due to scattered light inside the camera. This is an independent confirmation of the result derived for the diffuse calibration of IRAC by the Spitzer Science Centre (SSC).

From regression analyses we find that 843-MHz radio fluxes of Hii regions and mid-infrared (MIR) fluxes are linearly related for MSX at 8.3µm and Spitzer at 8.0µm, confirming the earlier MSX result by Cohen & Green. The median ratio of MIR/843-MHz diffuse continuum fluxes is 600x smaller in non-thermal than thermal regions, making it a sharp discriminant. The ratios are largely independent of morphology up to a size of ∼24arcmin. We provide homogeneous radio and MIR morphologies for all sources. MIR morphology is not uniquely related to radio structure. Compact regions may have MIR filaments and/or diffuse haloes, perhaps infrared counterparts to weakly ionized radio haloes found around compact Hii regions. We offer two IRAC colour-colour plots as quantitative diagnostics of diffuse Hii regions.


Abstract Copyright: 2006 The Authors. Journal compilation © 2006 RAS

Journal keyword(s): radiation mechanisms: non-thermal - radiation mechanisms: thermal - ISM: structure - supernova remnants - infrared: ISM - radio continuum: ISM

Nomenclature: Table 1: [CG2001] GLLL.ll+B.bb (No. G311.70+0.31) added.

CDS comments: In Chap. 10 : G313.45-0.13 is a misprint for G311.45-0.13

Simbad objects: 61

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