BLUEPRINT: Blue-dominant Lyman-α emission as evidence of gas inflow in ultra-low-mass galaxies at z = 3

Tamal Mukherjee; Zhihui Li; Tayyaba Zafar; Themiya Nanayakkara; Davide Tornotti; Luca Costantin; Imam Uzma Aalia

doi:10.1051/0004-6361/202659780

BLUEPRINT: Blue-dominant Lyman-α emission as evidence of gas inflow in ultra-low-mass galaxies at z = 3

Tamal Mukherjee^*
, Zhihui Li
, Tayyaba Zafar
, Themiya Nanayakkara
, Davide Tornotti
, Luca Costantin
, Imam Uzma Aalia

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

1 Downloads (Pure)

Abstract

We report the detection of a clumpy, blue-dominated Lyman-α (Lyα) emission at z = 3.066 located in the heart of a cosmic web filament in the MUSE eXtremely Deep Field (MXDF). It is spatially associated with the formation of two compact star-forming regions revealed by deep JWST/NIRCam imaging. Gas accretion in these regions is indicated by the blue-dominated Lyα profiles, spectral signatures that are rarely observed. Radiative transfer simulations of the Lyα profile using a clumpy multiphase model suggest a radial inflow of gas clumps with a velocity of ∼100 km/s. Embedded in this Lyα structure, the associated main galaxy dominates the stellar mass budget, while the two compact ultra-low-mass systems (log(M_★/M_⊙) = 6.3 − 6.9) have formed the bulk of their stellar mass in less than 7 Myr. These two components also have high specific star-formation rates and elevated ionisation parameters, consistent with recent bursty star formation. This system provides compelling observational evidence of how gas accretion, most likely from the cosmic web, can induce starbursts in ultra-low-mass galaxies.

Original language	English
Article number	A331
Pages (from-to)	1-8
Number of pages	8
Journal	Astronomy and Astrophysics
Volume	710
DOIs	https://doi.org/10.1051/0004-6361/202659780
Publication status	Published - Jun 2026

Bibliographical note

Keywords

cosmology: observations
galaxies: evolution
galaxies: high-redshift
galaxies: star formation

Access to Document

10.1051/0004-6361/202659780Licence: CC BY

Publisher version (open access)Final published version, 766 KBLicence: CC BY

Cite this

@article{0c572cfc47944b1698c3093f8cb346cc,

title = "BLUEPRINT: Blue-dominant Lyman-α emission as evidence of gas inflow in ultra-low-mass galaxies at z = 3",

abstract = "We report the detection of a clumpy, blue-dominated Lyman-α (Lyα) emission at z = 3.066 located in the heart of a cosmic web filament in the MUSE eXtremely Deep Field (MXDF). It is spatially associated with the formation of two compact star-forming regions revealed by deep JWST/NIRCam imaging. Gas accretion in these regions is indicated by the blue-dominated Lyα profiles, spectral signatures that are rarely observed. Radiative transfer simulations of the Lyα profile using a clumpy multiphase model suggest a radial inflow of gas clumps with a velocity of ∼100 km/s. Embedded in this Lyα structure, the associated main galaxy dominates the stellar mass budget, while the two compact ultra-low-mass systems (log(M★/M⊙) = 6.3 − 6.9) have formed the bulk of their stellar mass in less than 7 Myr. These two components also have high specific star-formation rates and elevated ionisation parameters, consistent with recent bursty star formation. This system provides compelling observational evidence of how gas accretion, most likely from the cosmic web, can induce starbursts in ultra-low-mass galaxies.",

keywords = "cosmology: observations, galaxies: evolution, galaxies: high-redshift, galaxies: star formation",

author = "Tamal Mukherjee and Zhihui Li and Tayyaba Zafar and Themiya Nanayakkara and Davide Tornotti and Luca Costantin and Aalia, \{Imam Uzma\}",

note = "{\textcopyright} The Authors 2026. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.",

year = "2026",

month = jun,

doi = "10.1051/0004-6361/202659780",

language = "English",

volume = "710",

pages = "1--8",

journal = "Astronomy and Astrophysics",

issn = "0004-6361",

publisher = "EDP Sciences",

}

TY - JOUR

T1 - BLUEPRINT

T2 - Blue-dominant Lyman-α emission as evidence of gas inflow in ultra-low-mass galaxies at z = 3

AU - Mukherjee, Tamal

AU - Li, Zhihui

AU - Zafar, Tayyaba

AU - Nanayakkara, Themiya

AU - Tornotti, Davide

AU - Costantin, Luca

AU - Aalia, Imam Uzma

N1 - © The Authors 2026. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

PY - 2026/6

Y1 - 2026/6

N2 - We report the detection of a clumpy, blue-dominated Lyman-α (Lyα) emission at z = 3.066 located in the heart of a cosmic web filament in the MUSE eXtremely Deep Field (MXDF). It is spatially associated with the formation of two compact star-forming regions revealed by deep JWST/NIRCam imaging. Gas accretion in these regions is indicated by the blue-dominated Lyα profiles, spectral signatures that are rarely observed. Radiative transfer simulations of the Lyα profile using a clumpy multiphase model suggest a radial inflow of gas clumps with a velocity of ∼100 km/s. Embedded in this Lyα structure, the associated main galaxy dominates the stellar mass budget, while the two compact ultra-low-mass systems (log(M★/M⊙) = 6.3 − 6.9) have formed the bulk of their stellar mass in less than 7 Myr. These two components also have high specific star-formation rates and elevated ionisation parameters, consistent with recent bursty star formation. This system provides compelling observational evidence of how gas accretion, most likely from the cosmic web, can induce starbursts in ultra-low-mass galaxies.

AB - We report the detection of a clumpy, blue-dominated Lyman-α (Lyα) emission at z = 3.066 located in the heart of a cosmic web filament in the MUSE eXtremely Deep Field (MXDF). It is spatially associated with the formation of two compact star-forming regions revealed by deep JWST/NIRCam imaging. Gas accretion in these regions is indicated by the blue-dominated Lyα profiles, spectral signatures that are rarely observed. Radiative transfer simulations of the Lyα profile using a clumpy multiphase model suggest a radial inflow of gas clumps with a velocity of ∼100 km/s. Embedded in this Lyα structure, the associated main galaxy dominates the stellar mass budget, while the two compact ultra-low-mass systems (log(M★/M⊙) = 6.3 − 6.9) have formed the bulk of their stellar mass in less than 7 Myr. These two components also have high specific star-formation rates and elevated ionisation parameters, consistent with recent bursty star formation. This system provides compelling observational evidence of how gas accretion, most likely from the cosmic web, can induce starbursts in ultra-low-mass galaxies.

KW - cosmology: observations

KW - galaxies: evolution

KW - galaxies: high-redshift

KW - galaxies: star formation

UR - https://www.scopus.com/pages/publications/105042958612

UR - https://purl.org/au-research/grants/arc/DP230103161

U2 - 10.1051/0004-6361/202659780

DO - 10.1051/0004-6361/202659780

M3 - Article

AN - SCOPUS:105042958612

SN - 0004-6361

VL - 710

SP - 1

EP - 8

JO - Astronomy and Astrophysics

JF - Astronomy and Astrophysics

M1 - A331

ER -