A pilot method to determine the high mass end of the Stellar Initial Mass Function in galaxies using UVIT, H$α$-MUSE observations and applied to NGC628

S Amrutha; Mousumi Das

doi:10.3847/1538-4357/add68d

paper

A pilot method to determine the high mass end of the Stellar Initial Mass Function in galaxies using UVIT, H $α$ -MUSE observations and applied to NGC628

arXiv:2505.03226 · doi:10.3847/1538-4357/add68d

Abstract

We present a pilot method to estimate the high-mass initial mass function (IMF) across the arm, interarm, and spur regions in galaxies and apply it to NGC 628. We extracted star-forming complexes (SFCs) from H $α$ VLT/MUSE and UVIT (FUV and NUV) observations of NGC 628 and used ALMA observations to define the molecular gas distribution. We find that the extinction-corrected H $α$ and FUV luminosities correlate well. Using the fact that O stars have a shorter lifetime (10 $^{7}$ yr) compared to B stars (10 $^{8}$ yr), we estimated the approximate number of O stars from H $α$ emission, and the number of B0 ( $M_{*} > 10 M_{⊙}$ ), and B1 ( $10 M_{⊙} \geq M_{*} \geq 3 M_{⊙}$ ) stars using FUV, NUV observations. We derived the IMF index ( $α$ ) for different regions using O to B0 ( $α_{1}$ ) and B0 to B1 ( $α_{2}$ ) stellar ratios. Our findings indicate that if we assume H $α$ arises only from O8-type stars, the resulting $α_{1}$ value is consistent with the canonical IMF index. It steepens when we assume O stars with masses up to 100 $M_{⊙}$ with mean $α_{1} = 3.16 \pm 0.62$ . However, the $α_{2}$ does not change for large variations in the O-star population, and the mean $α = 2.64 \pm 0.14$ . When we include only blue SFCs ( $F U V - N U V \leq 0.3$ ), mean $α_{2}$ is $2.43 \pm 0.06$ . The IMF variation for SFCs in arms and spurs is insignificant. We also find that $α_{2}$ correlates with different properties of the SFCs, the most prominent being the extinction-corrected UV color (FUV-NUV).

Accepted in ApJ

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Star Formation Beyond the Optical Disk : The Low-Density Outskirts of NGC2090

A pilot method to determine the high mass end of the Stellar Initial Mass Function in galaxies using UVIT, Hα-MUSE observations and applied to NGC628

Abstract

References in corpus (74)

Cited by in corpus (1)

A pilot method to determine the high mass end of the Stellar Initial Mass Function in galaxies using UVIT, H $α$ -MUSE observations and applied to NGC628