Issue |
A&A
Volume 680, December 2023
|
|
---|---|---|
Article Number | L5 | |
Number of page(s) | 5 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202348202 | |
Published online | 11 December 2023 |
Letter to the Editor
Compact to extended Lyman-α emitters in MAGPI: Strong blue-peak emission at z ≳ 3
1
School of Mathematical and Physical Sciences, Macquarie University, NSW, 2109
Australia
e-mail: tamal.mukherjee@hdr.mq.edu.au
2
Macquarie University Astrophysics and Space Technologies Research Centre, Sydney, NSW, 2109
Australia
3
Centre for Astrophysics and Supercomputing, Swinburne University of Technology, PO Box 218 Hawthorn, 3122 VIC, Australia
4
Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT, 2611
Australia
5
International Centre for Radio Astronomy Research (ICRAR), Curtin University, Bentley, WA, Australia
6
International Centre for Radio Astronomy Research (ICRAR), The University of Western Australia, Crawley, WA, 6009
Australia
7
School of Physics, University of New South Wales, Sydney, NSW, 2052
Australia
8
Sydney Institute for Astronomy, School of Physics, University of Sydney, NSW, 2006
Australia
9
ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO-3D), Australia
Received:
9
October
2023
Accepted:
9
November
2023
We report the discovery of three double-peaked Lyman-α emitters (LAEs) exhibiting strong blue-peak emission at 2.9 ≲ z ≲ 4.8 in the VLT/MUSE data obtained as part of the Middle Ages Galaxy Properties with Integral Field Spectroscopy (MAGPI) survey. These strong blue-peak systems provide a unique window into the scattering of Lyα photons by neutral hydrogen (H I), suggesting gas inflows along the line of sight and low H I column density. Two of them at z = 2.9 and z = 3.6, are spatially extended halos with their core regions clearly exhibiting stronger emission at the blue peak than at the red peak. However, spatial variations in the peak ratio and peak separation are evident over 25 × 26 kpc (z = 2.9) and 19 × 28 kpc (z = 3.6) regions in these extended halos. Notably, these systems do not fall in the regime of Lyα blobs or nebulae. To the best of our knowledge, such a Lyα halo with a dominant blue core has not been observed previously. In contrast, the LAE at z ∼ 4.8 is a compact system spanning a 9 × 9 kpc region and stands as the highest-redshift strong blue-peak emitter ever detected. The peak separation of the bright cores in these three systems ranges from Δpeak ∼ 370 to 660 km s−1. The observed overall trend of decreasing peak separation with increasing radius is supposed to be controlled by H I column density and gas covering fraction. Based on various estimations, in contrast to the compact LAE, our halos are found to be good candidates for Lyman-continuum (LyC) leakers. These findings shed light on the complex interplay between Lyα emission, gas kinematics, and ionizing radiation properties, offering valuable insights into the evolution and nature of high-redshift galaxies.
Key words: galaxies: evolution / galaxies: high-redshift / cosmology: observations
© The Authors 2023
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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