J/A+A/684/A71 NGC 628, NGC 1365 and NGC 7496 UVIT FUV images (Ujjwal+, 2024)
Disentangling the association of PAH molecules with star formation. Insights
from James Webb Space Telescope and from the Ultraviolet Imaging Telescope.
Ujjwal K., Kartha S.S., Akhil K.R., Blesson M., Smitha S., Sudheesh T.P.,
Robin T.
<Astron. Astrophys. 684, A71 (2024)>
=2024A&A...684A..71U 2024A&A...684A..71U (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Ultraviolet ; Infrared
Keywords: ISM: molecules - galaxies: ISM - galaxies: star formation -
infrared: galaxies - ultraviolet: galaxies
Abstract:
Polycyclic Aromatic Hydrocarbons (PAHs) are ubiquitous complex
molecules in the interstellar medium and are used as an indirect
indicator of star-formation. On the other hand the ultraviolet (UV)
emission from the young massive stars directly traces the star
formation activity in a galaxy. The James Webb Space Telescope (JWST),
along with the UltraViolet Imaging Telescope (UVIT), opened up a new
window of opportunity to make a better understanding of the properties
of the PAH molecules associated with the star-forming regions.
In this study, we investigate how the resolved scale properties of PAH
molecules in nearby galaxies are affected by star- formation.
We analyze the PAH features observed at 3.3, 7.7, and 11.3um using
F335M, F770W, and F1130W images obtained from JWST. These images help
us identify and quantify the PAH molecules. Additionally, we utilize
UVIT images to assess the star formation associated with these PAH
emitting regions. Our study focuses on three galaxies, namely NGC 628,
NGC 1365, and NGC 7496, selected based on the availability of both
JWST and UVIT images. Bright PAH emission regions are identified in
the JWST images, and their corresponding UV emission is estimated
using the UVIT images. We quantify the star formation properties of
these PAH emitting regions using the UVIT images. Furthermore, we
investigate the relationship between the star formation surface
density ({SIGMA}SFR) and the PAH ratios to better understand the
impact of star formation on the properties of PAH molecules.
Based on the resolved scale study on the PAH bright regions using JWST
images, we found that the fraction of ionized PAH molecules is high in
the star-forming regions with high {SIGMA}SFR. We observed that
emission from smaller PAH molecules is more in the star-forming
regions with higher {SIGMA}SFR.
Our study suggests that the PAH molecules excited by the photons from
SF regions with higher {SIGMA}SFR are dominantly smaller and ionized
molecules.UV photons from the star-forming regions could be the reason
for a higher fraction of the ionized PAHs. We suggest that the effect
of high temperature in the star-forming regions and the formation of
smaller PAH molecules in the star-forming regions might also be
resulting in the higher fraction of emission in the F335MPAH band.
Description:
UVIT data of the sample of galaxies NGC 628 (PI: ASK pati), NGC 1365
(PI: C S Stalin) and NGC 7496 (PI: Erik Rosolowsky) obtained from the
AstroSat ISSDC archive We made use of F148W (λpeak∼1481Å)
images for the study. The Level 1 data was reduced using the software
CCDLab.
Objects:
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RA (2000) DE Designation(s)
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01 36 41.74 +15 47 01.1 NGC 628 = M 74
03 33 36.45 -36 08 26.3 NGC 1365 = LEDA 13179
23 09 47.28 -43 25 40.2 NGC 7496 = LEDA 70588
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
list.dat 106 3 Information on fits images
fits/* . 3 Individual fits images
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Byte-by-byte Description of file: list.dat
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Bytes Format Units Label Explanations
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1- 9 F9.5 deg RAdeg Right Ascension of center (J2000)
11- 19 F9.5 deg DEdeg Declination of center (J2000)
21- 24 I4 --- Nx Number of pixels along X-axis
26- 29 I4 --- Ny Number of pixels along Y-axis
31- 40 A10 "datime" Obs.date Observation date
42- 47 I6 Kibyte size Size of FITS file
49- 78 A30 --- FileName Name of FITS file, in subdirectory fits
80-106 A27 --- Title Title of the FITS file
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Acknowledgements:
Ujjwal Krishnan, ujjwal.krishnan(at)res.christuniversity.in
(End) Patricia Vannier [CDS] 09-Jan-2024