J/A+A/707/A144 Local LIRGs clumps physical properties (Sanchez-Garcia+, 2026)
Spatially resolved star formation relations in local LIRGs along the complete
merger sequence.
Sanchez-Garcia M., Diaz-Santos T., Barcos-Munoz L., Evans A.S., Song Y.,
Pereira-Santaella M., Garcia-Burillo S., Linden S.T., Ricci C., Lenkic L.,
Zanella A., Armus L., Eibensteiner C., Teng Y.-H., Saravia A., Buiten V.A.,
Privon G.C., Torres-Alba N., Saito T., Larson K.L., Bianchin M.,
Medling A.M., Lai T., Donnelly G.P., Charmandaris V., Bohn T., Lofaro C.M.,
Meza G.
<Astron. Astrophys. 707, A144 (2026)>
=2026A&A...707A.144S 2026A&A...707A.144S (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, IR ; Molecular clouds ; Carbon monoxide ;
Morphology ; Radio lines
Keywords: ISM: clouds - galaxies: interactions - galaxies: ISM -
galaxies: star formation
Abstract:
We investigated the properties of the interstellar medium (ISM) at
giant molecular cloud (GMC) scales (∼100 pc) in a sample of 27
nearby luminous infrared galaxies (LIRGs) spanning all interacting
stages along the merger sequence, i.e. from isolated systems to
late-stage mergers. In particular, we study the relations between
star-formation (SF) and molecular gas surface density as a function of
the interaction stage by (1) defining beam-sized (unresolved,
line-of-sight) regions and (2) identifying actual gas clumps and
physical structures within the galaxies. In total, we identify more
than 4000 beam-sized CO-emitting regions defined on scales of ∼100pc
and more than 1000 molecular gas clumps in the sample. To map the
distribution of molecular gas we used the Atacama Large
Millimeter/submillimeter Array (ALMA) to observe the J=2-1 CO
transition, and to map the distribution of star formation we used the
Hubble Space Telescope (HST) observations of the Paα or Paβ
hydrogen recombination lines. We derived spatially resolved
Kennicutt-Schmidt (KS) relations for each LIRG in the sample. When
using beam-sized regions, we find that 67% of galaxies follow a single
relation between {SIGMA}SFR and {SIGMA}H2. However, in the remaining
galaxies, the relation splits into two branches - one characterised by
higher {SIGMA}SFR and {SIGMA}H2, the other by lower value - indicating
the presence of a duality in this relation. In contrast, when using
physical gas clumps, the duality disappears and all galaxies show a
single trend. These results provide two complementary perspectives
when studying the star formation process. The first maximises the
number statistics (beam-sized regions), and the second focuses on
actual structures associated with gas clumps in which the measured
sizes have a physical meaning. We also studied other ISM and clump
properties as a function of the merger stage of the LIRG systems. We
find that isolated galaxies and systems in early stages of interaction
exhibit smaller amounts of gas and lower star formation rates (SFRs).
As the merger progresses, however, the amount of gas in the central
kiloparsecs of the galaxy undergoing the merger increases, along with
the SFR, and the slope of the KS relation becomes steeper, indicating
an increase in the SF efficiency of the molecular gas clumps. Clumps
in late-stage mergers are predominantly located at small distances
from the nucleus, confirming that most of the activity is concentrated
in the central regions. Interestingly, the relation between the star
formation efficiency and the boundedness parameter (which measures the
effects of gravity against velocity dispersion) evolves from being
roughly flat in the early stages of the merger to becoming positive in
the final phases, indicating that clump self-gravity only starts to
regulate the star formation process between the early and mid merger
stages.
Description:
This catalog provides the main physical properties of clumps
identified in the sample of local LIRGs using ALMA CO(2-1)
observations and HST recombination line data.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 135 1027 Catalog of clumps
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ClumpID Clump identification number
6- 25 F20.16 deg RAdeg Right ascension (J2000)
30- 49 F20.16 deg DEdeg Declination (J2000)
52- 71 F20.16 pc Reff Effective radius
72- 93 F22.18 Jy.km/s FluxCO CO(2-1) integrated flux
96-117 E22.18 mW/m2 FluxPa Paschen recombination line flux
(in erg/s/cm2)
120-135 A16 --- Galaxy Galaxy name
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Acknowledgements:
Maria Sanchez-Garcia, msanchez(at)ia.forth.gr
(End) Patricia Vannier [CDS] 12-Jan-2026