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Paper: Comparison of Bar Strengths in the Optical and Near-infrared
Volume: 390, Pathways Through an Eclectic Universe
Page: 320
Authors: Speltincx, T.; Laurikainen, E.; Salo, H.; Buta, R.J.; Knapen, J.H.
Abstract: Bars are expected to play an important role in galactic dynamics. Since the rest-frame wavelength of near-infrared images of high redshift galaxies lies in the optical, a reliable comparison of low and high redshift bars requires an understanding of how the properties of a bar depend on the observing wavelength. For this purpose, we compare bar strengths for galaxies from the osubsgs sample in the B- and H-bands, using the gravitational bar torque method. We find that the ratio of bar torques in the B- and H-bands is fairly close to unity (QB/H ∼ 1.25) and independent of the morphological type. Hence, we can make a good estimate of the “real” bar strength for galaxies at high redshift from the observed one, even if the morphological classification were uncertain. Also, we show that the gravitational bar torque method using a polar grid gives satisfactory results when applied to degraded images that mimic high redshift images. Typical errors in bar strength remain below 10% as long as the total bar length is at least ∼10 pixels.
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