1,419 research outputs found
Redshifting galaxies from DESI to JWST CEERS: Correction of biases and uncertainties in quantifying morphology
Observations of high-redshift galaxies with unprecedented detail have now
been rendered possible with JWST. However, accurately quantifying their
morphology remains uncertain due to potential biases and uncertainties. To
address this issue, we used a sample of 1816 nearby DESI galaxies, with a mass
range of , to compute artificial images of galaxies
of the same mass located at and observed at rest-frame
optical wavelength in CEERS. We analyzed the effects of cosmological redshift
on the measurements of Petrosian radius (), half-light radius (),
asymmetry (), concentration (), axis ratio (), and S\'ersic index
(). Our results show that and , calculated using
non-parametric methods, are slightly overestimated due to PSF smoothing, while
, , and obtained through model fitting does not exhibit
significant biases. We improve the computation of by incorporating a more
accurate noise effect removal procedure. Due to PSF asymmetry, there is a minor
overestimation of for intrinsically symmetric galaxies. However, for
intrinsically asymmetric galaxies, PSF smoothing dominates and results in an
underestimation of , an effect that becomes more significant with higher
intrinsic or at lower resolutions. Moreover, PSF smoothing also leads to an
underestimation of , which is notably more pronounced in galaxies with
higher intrinsic or at lower resolutions. We developed functions based on
resolution level, defined as FWHM, for correcting these biases and the
associated statistical uncertainties. Applying these corrections, we measured
the bias-corrected morphology for the simulated CEERS images and we find that
the derived quantities are in good agreement with their intrinsic values --
except for , which is robust only for angularly large galaxies where
.Comment: 21 pages, 17 figures; A&A in pres
Multiwavelength Bulge-Disk Decomposition for the Galaxy M81 (NGC 3031). I. Morphology
A panchromatic investigation of morphology for the early-type spiral galaxy
M81 is presented in this paper. We perform bulge-disk decomposition in M81
images at totally 20 wavebands from FUV to NIR obtained with GALEX, Swift,
SDSS, WIYN, 2MASS, WISE, and Spitzer. Morphological parameters such as Sersic
index, effective radius, position angle, and axis ratio for the bulge and the
disk are thus derived at all the wavebands, which enables quantifying the
morphological K-correction for M81 and makes it possible to reproduce images
for the bulge and the disk in the galaxy at any waveband. The morphology as a
function of wavelength appears as a variable-slope trend of the Sersic index
and the effective radius, in which the variations are steep at UV--optical and
shallow at optical--NIR bands; the position angle and the axis ratio keep
invariable at least at optical--NIR bands. It is worth noting that, the Sersic
index for the bulge reaches to about 4--5 at optical and NIR bands, but drops
to about 1 at UV bands. This difference brings forward a caveat that, a
classical bulge is likely misidentified for a pseudo-bulge or no bulge at high
redshifts where galaxies are observed through rest-frame UV channels with
optical telescopes. The next work of this series is planned to study spatially
resolved SEDs for the bulge and the disk, respectively, and thereby explore
stellar population properties and star formation/quenching history for the the
galaxy composed of the subsystems.Comment: 48 Pages, 38 Figures, 5 Tables; Accepted for Publication in The
Astrophysical Journal Supplement Serie
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