J/A+A/707/A13 Tracing ionized gas kinematics in LBAs (Leon Contreras+, 2026)
Tracing ionized gas kinematics in Lyman-Break Analogs.
Implications for star formation compactness and outflow properties.
Leon Contreras A., Amorin R., Llerena M., Fernandez V.
<Astron. Astrophys. 707, A13 (2026)>
=2026A&A...707A..13L 2026A&A...707A..13L (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Spectroscopy ; Redshifts
Keywords: galaxies: ISM - galaxies: kinematics and dynamics -
galaxies: starburst
Abstract:
The ionized gas kinematics of low-mass starburst galaxies is a tracer
of galaxy interactions and feedback processes, which are key for
understanding massive star formation, chemical enrichment, and galaxy
evolution.
We study the ionized gas kinematics and outflow properties in a sample
of Lyman-Break Analogs (LBAs) at z∼0.1-0.3, characterized by their
compact morphologies, high UV luminosities, and strong emission lines,
which are common at higher redshifts.
We use high-resolution VLT/X-Shooter spectra of 14 compact,
UV-luminous LBAs to model the complex
[OIII]λλ4959,5007Å and Balmer line profiles with
multi-Gaussian fits.
LBAs show complex kinematics, with emission lines best reproduced by
narrow (σ<90km/s) and broad (σ>90km/s) components in all
galaxies. The narrow-line kinematics is highly turbulent, likely
driven by massive star-forming clumps. The luminosities and line
ratios of the narrow components are typical of giant HII regions. We
interpret the broader components as ionized outflows driven by strong
winds of massive stars and supernovae. In galaxies with highly complex
profiles and disturbed morpholo- gies, ongoing interactions or mergers
are found to contribute to the broad components. We find outflow
velocities in the range vout∼200km/s to 500km/s. Simple models yield
outflow mass rates of 0.20-2.72M☉/yr and mass-loading factors
η∼0.03-0.81. We find that η shows a mild increasing trend at
lower stellar masses, in agreement with previous observational studies
and predictions from FIRE-2 and Illustris-TNG simulations. Compact
starburst morphologies may modulate the η-M* relation, showing a
strong {SIGMA}SFR-η correlation, i.e., more compact starbursts
drive stronger outflows. We find a good agreement with similar
findings in star-forming galaxies at high-redshift (z∼2-9),
including those from recent JWST observations.
Our results highlight the relevance of detailed studies of the ionized
gas kinematics in local UV-compact starbursts to improve our
understanding of feedback processes in low-mass, rapidly star-forming
galaxies
Description:
We present the ionized-gas kinematics of a sample of 14 Lyman-Break
Analogs (LBAs) observed with VLT/X-Shooter. Using high-resolution
emission-line profiles, we perform multi-component Gaussian modeling
to characterize gas turbulence, outflow velocities, star-formation
compactness, mass-loading factors, and mass-outflow rates.
This catalogue contains the kinematic parameters derived from the
multi- component Gaussian decomposition of the brightest optical
emission lines in 14 Lyman-Break Analogs observed with VLT/X-Shooter.
The analyzed emission lines include Hα, Hβ,
[OIII]4959,5007, [NII]6584, and [SII]6716,6731. For each galaxy and
emission line, we provide the parameters of each Gaussian
component-broad and narrow-including intrinsic velocity dispersion,
radial velocity offset, flux, and emission-measure fraction. These
measurements characterize the kinematics of both turbulent
star-forming gas and ionized outflows.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 67 14 Information on the selected sample
table2.dat 66 254 Kinematic parameters
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Galaxy identifier
12- 13 I2 h RAh Right ascension (J2000)
15- 16 I2 min RAm Right ascension (J2000)
18- 22 F5.2 s RAs Right ascension (J2000)
24 A1 --- DE- Declination sign (J2000)
25- 26 I2 deg DEd Declination (J2000)
28- 29 I2 arcmin DEm Declination (J2000)
31- 35 F5.2 arcsec DEs Declination (J2000)
37- 42 F6.4 --- z Redshift (1)
44- 67 A24 --- Name Galaxy name
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Note (1): The redshift was obtained from the SDSS spectra by Heckman et al.
(2015ApJ...809..147H 2015ApJ...809..147H).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- ID Galaxy identifier
12- 15 I4 0.1nm lambda0 Rest-frame wavelength
(nominal laboratory value)
17- 22 A6 --- Ion Ion species
24- 25 A2 --- Comp Component flag (1)
27- 31 F5.1 km/s sigmaint Intrinsic velocity dispersion
33- 36 F4.1 km/s e_sigmaint Uncertainty in sigma_int
38- 43 F6.1 km/s RV Radial velocity relative to
systemic velocity (2)
45- 48 F4.1 km/s e_RV Uncertainty in RV
50- 55 F6.1 10-20W/m2 Flux Flux of the component
(in 10-17erg/s/cm2 unit)
57- 60 F4.1 10-20W/m2 e_Flux Uncertainty in flux
(in 10-17erg/s/cm2 unit)
62- 66 F5.1 % EM Emission-measure fraction (3)
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Note (1): Component flag:
B, B1, B2 : Broad components
N, N1-N4 : Narrow components
Note (2): sigmaint and RV are corrected for instrumental and thermal broadening.
Note (3): EM is the fractional contribution of each Gaussian component.
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Acknowledgements:
Ricardo Amorin, amorin(at)iaa.es
(End) Ana Leon Contreras [ULS, Chile], Patricia Vannier [CDS] 26-Nov-2025