PROBING THE 12CO(1-0)/13CO(1-0) LINE RATIOS, MOLECULAR GAS MASS AND GAS KINEMATICS ACROSS THE DISC OF THE SPIRAL GALAXY NGC 5248


Creative Commons License

Topal S.

ISPEC 10th INTERNATIONAL CONFERENCE ON ENGINEERING & NATURAL SCIENCES, Siirt, Turkey, 16 - 18 May 2021, pp.100-101

  • Publication Type: Conference Paper / Summary Text
  • City: Siirt
  • Country: Turkey
  • Page Numbers: pp.100-101

Abstract

Carbon monoxide, as the second most abundant molecule of the interstellar medium (ISM), is

a widely used tracer for probing the physics and kinematics of the molecular gas clouds in

galaxies. In this study, we probe the physics of the molecular gas across the disc of the nearby

barred spiral galaxy NGC 5248 using 12CO(1-0) and 13CO(1-0) molecular transitions. We

selected 15 positions bright in CO emission over the galaxy’s disc. Assuming a galactic COto-

H2 conversion factor (X_CO) for the positions over the disc and ten times lower X_CO value

for the center, we also estimated the molecular gas mass and gas surface density at all selected

positions. Our main results are summarized as follows. The CO integrated intensity is the

highest in the central regions while it shows almost a flat distribution along the eastern and

western arms of the galaxy. Velocity dispersion is higher in the south-eastern (SE) side of the

disc compared to the north-western (NW) side and the position-velocity diagram indicates a

central bar. Apart from the central depression in gas mass (because of the assumed depression

in the X_CO at the center of the galaxy) other central 6 positions have higher gas mass and gas

surface density compared to the regions along the arms where the values rather show a flat

distribution. The 12CO(1-0)/13CO(1-0) ratio is at its highest value at the center and it tends to

decrease as a function of distance from the galactic center, although at most positions in the

SE and NW of the disc the ratios are only lower limits. This indicates that the gas gets less

diffuse from the center to the outskirts of the galaxy, i.e. the role of supernova explosions,

stellar winds and strong ultraviolet (UV) emission in the ISM could be less dominant in the

outskirts than in the center. The physical properties of the gas and the role of stellar

populations in the physics of the ISM over the disc of the galaxy will further be studied with

the additional data from UV radiation and 3μm to 24μm dust emissions.