Deprojection of external barred galaxies from photometry. (arXiv:2110.06955v1 [astro-ph.GA])
<a href="http://arxiv.org/find/astro-ph/1/au:+Tahmasebzadeh_B/0/1/0/all/0/1">Behzad Tahmasebzadeh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Zhu_L/0/1/0/all/0/1">Ling Zhu</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Shen_J/0/1/0/all/0/1">Juntai Shen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gerhard_O/0/1/0/all/0/1">Ortwin Gerhard</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Qin_Y/0/1/0/all/0/1">Yujing Qin</a>
The observations of external galaxies are projected to the 2D sky plane.
Reconstructing the 3D intrinsic density distribution of a galaxy from the 2D
image is challenging, especially for barred galaxies, but is a critical step
for constructing galactic dynamical models. Here we present a method for
deprojecting barred galaxies and we validate the method by testing against mock
images created from an N-body simulation with a peanut-shaped bar. We decompose
a galaxy image into a bulge (including a bar) and a disk. By subtracting the
disk from the original image a barred bulge remains. We perform multi-Gaussian
expansion (MGE) fit to each component, then we deproject them separately by
considering the barred bulge is triaxial while the disk is axisymmetric. We
restrict the barred bulge to be aligned in the disk plane and has a similar
thickness to the disk in the outer regions. The 3D density distribution is thus
constructed by combining the barred bulge and the disk. Our model can generally
recover the 3D density distribution of disk and inner barred bulge regions,
although not a perfect match to the peanut-shaped structure. By using the same
initial conditions, we integrate the orbits in our model-inferred potential and
the true potential by freezing the N-body simulation. We find that 85% of all
these orbits have similar morphologies in these two potentials, and our model
supports the orbits that generate a boxy/peanut-shaped structure and an
elongated bar similar to these in the true potential.
The observations of external galaxies are projected to the 2D sky plane.
Reconstructing the 3D intrinsic density distribution of a galaxy from the 2D
image is challenging, especially for barred galaxies, but is a critical step
for constructing galactic dynamical models. Here we present a method for
deprojecting barred galaxies and we validate the method by testing against mock
images created from an N-body simulation with a peanut-shaped bar. We decompose
a galaxy image into a bulge (including a bar) and a disk. By subtracting the
disk from the original image a barred bulge remains. We perform multi-Gaussian
expansion (MGE) fit to each component, then we deproject them separately by
considering the barred bulge is triaxial while the disk is axisymmetric. We
restrict the barred bulge to be aligned in the disk plane and has a similar
thickness to the disk in the outer regions. The 3D density distribution is thus
constructed by combining the barred bulge and the disk. Our model can generally
recover the 3D density distribution of disk and inner barred bulge regions,
although not a perfect match to the peanut-shaped structure. By using the same
initial conditions, we integrate the orbits in our model-inferred potential and
the true potential by freezing the N-body simulation. We find that 85% of all
these orbits have similar morphologies in these two potentials, and our model
supports the orbits that generate a boxy/peanut-shaped structure and an
elongated bar similar to these in the true potential.
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