Infalling gas in a Lyman-α blob

Yiping Ao; Zheng Zheng; Christian Henkel; Shiyu Nie; Alexandre Beelen; Renyue Cen; Mark Dijkstra; Paul J. Francis; James E. Geach; Kotaro Kohno; Matthew D. Lehnert; Karl M. Menten; Junzhi Wang; Axel Weiss

doi:10.1038/s41550-020-1033-3

Infalling gas in a Lyman-α blob

Yiping Ao^*, Zheng Zheng, Christian Henkel, Shiyu Nie, Alexandre Beelen, Renyue Cen, Mark Dijkstra, Paul J. Francis, James E. Geach, Kotaro Kohno, Matthew D. Lehnert, Karl M. Menten, Junzhi Wang, Axel Weiss

^*Corresponding author for this work

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

25 Citations (Scopus)

Abstract

Lyman-α blobs (LABs) are spatially extended nebulae of emission in the Lyman-α (Lyα) line of hydrogen, seen at high redshifts^1,2, and most commonly found in the dense environment of star-forming galaxies^3,4. A recent study showed that nearly 100% of the sky is covered by Lyα emission around high-redshift galaxies^5–7. The origin of Lyα emission in the LABs is still unclear and under debate⁸. It may be powered by photoionization involving galactic superwinds/outflows, resonant scattering of Lyα photons from starbursts or active galactic nuclei^9–16, or by cooling radiation from cold streams of gas accreting onto galaxies^17,18, as demonstrated by recent simulations¹⁹. Here we analyse the gas kinematics within a LAB, providing rare observational evidence for infalling gas. This is consistent with the release of gravitational accretion energy as cold streams radiate Lyα photons. It also provides direct evidence for possible cold streams feeding the central galaxies. The mass of the infalling gas is not important in comparison to the gas mass consumed by star formation, and is also not the major powering source of Lyα emission, but it hints at another mechanism to explain the origin of the extended Lyα emission around young galaxies.

Original language	English
Pages (from-to)	670-674
Number of pages	5
Journal	Nature Astronomy
Volume	4
Issue number	7
DOIs	https://doi.org/10.1038/s41550-020-1033-3
Publication status	Published - 1 Jul 2020

Access to Document

10.1038/s41550-020-1033-3

Cite this

@article{9ba023512fe74b6c8315de279d90f403,

title = "Infalling gas in a Lyman-α blob",

abstract = "Lyman-α blobs (LABs) are spatially extended nebulae of emission in the Lyman-α (Lyα) line of hydrogen, seen at high redshifts1,2, and most commonly found in the dense environment of star-forming galaxies3,4. A recent study showed that nearly 100% of the sky is covered by Lyα emission around high-redshift galaxies5–7. The origin of Lyα emission in the LABs is still unclear and under debate8. It may be powered by photoionization involving galactic superwinds/outflows, resonant scattering of Lyα photons from starbursts or active galactic nuclei9–16, or by cooling radiation from cold streams of gas accreting onto galaxies17,18, as demonstrated by recent simulations19. Here we analyse the gas kinematics within a LAB, providing rare observational evidence for infalling gas. This is consistent with the release of gravitational accretion energy as cold streams radiate Lyα photons. It also provides direct evidence for possible cold streams feeding the central galaxies. The mass of the infalling gas is not important in comparison to the gas mass consumed by star formation, and is also not the major powering source of Lyα emission, but it hints at another mechanism to explain the origin of the extended Lyα emission around young galaxies.",

author = "Yiping Ao and Zheng Zheng and Christian Henkel and Shiyu Nie and Alexandre Beelen and Renyue Cen and Mark Dijkstra and Francis, {Paul J.} and Geach, {James E.} and Kotaro Kohno and Lehnert, {Matthew D.} and Menten, {Karl M.} and Junzhi Wang and Axel Weiss",

note = "Publisher Copyright: {\textcopyright} 2020, Springer Nature Limited.",

year = "2020",

month = jul,

day = "1",

doi = "10.1038/s41550-020-1033-3",

language = "English",

volume = "4",

pages = "670--674",

journal = "Nature Astronomy",

issn = "2397-3366",

publisher = "Nature Publishing Group",

number = "7",

}

TY - JOUR

T1 - Infalling gas in a Lyman-α blob

AU - Ao, Yiping

AU - Zheng, Zheng

AU - Henkel, Christian

AU - Nie, Shiyu

AU - Beelen, Alexandre

AU - Cen, Renyue

AU - Dijkstra, Mark

AU - Francis, Paul J.

AU - Geach, James E.

AU - Kohno, Kotaro

AU - Lehnert, Matthew D.

AU - Menten, Karl M.

AU - Wang, Junzhi

AU - Weiss, Axel

PY - 2020/7/1

Y1 - 2020/7/1

N2 - Lyman-α blobs (LABs) are spatially extended nebulae of emission in the Lyman-α (Lyα) line of hydrogen, seen at high redshifts1,2, and most commonly found in the dense environment of star-forming galaxies3,4. A recent study showed that nearly 100% of the sky is covered by Lyα emission around high-redshift galaxies5–7. The origin of Lyα emission in the LABs is still unclear and under debate8. It may be powered by photoionization involving galactic superwinds/outflows, resonant scattering of Lyα photons from starbursts or active galactic nuclei9–16, or by cooling radiation from cold streams of gas accreting onto galaxies17,18, as demonstrated by recent simulations19. Here we analyse the gas kinematics within a LAB, providing rare observational evidence for infalling gas. This is consistent with the release of gravitational accretion energy as cold streams radiate Lyα photons. It also provides direct evidence for possible cold streams feeding the central galaxies. The mass of the infalling gas is not important in comparison to the gas mass consumed by star formation, and is also not the major powering source of Lyα emission, but it hints at another mechanism to explain the origin of the extended Lyα emission around young galaxies.

AB - Lyman-α blobs (LABs) are spatially extended nebulae of emission in the Lyman-α (Lyα) line of hydrogen, seen at high redshifts1,2, and most commonly found in the dense environment of star-forming galaxies3,4. A recent study showed that nearly 100% of the sky is covered by Lyα emission around high-redshift galaxies5–7. The origin of Lyα emission in the LABs is still unclear and under debate8. It may be powered by photoionization involving galactic superwinds/outflows, resonant scattering of Lyα photons from starbursts or active galactic nuclei9–16, or by cooling radiation from cold streams of gas accreting onto galaxies17,18, as demonstrated by recent simulations19. Here we analyse the gas kinematics within a LAB, providing rare observational evidence for infalling gas. This is consistent with the release of gravitational accretion energy as cold streams radiate Lyα photons. It also provides direct evidence for possible cold streams feeding the central galaxies. The mass of the infalling gas is not important in comparison to the gas mass consumed by star formation, and is also not the major powering source of Lyα emission, but it hints at another mechanism to explain the origin of the extended Lyα emission around young galaxies.

UR - http://www.scopus.com/inward/record.url?scp=85081689763&partnerID=8YFLogxK

U2 - 10.1038/s41550-020-1033-3

DO - 10.1038/s41550-020-1033-3

M3 - Article

SN - 2397-3366

VL - 4

SP - 670

EP - 674

JO - Nature Astronomy

JF - Nature Astronomy

IS - 7

ER -

Infalling gas in a Lyman-α blob

Abstract

Access to Document

Other files and links

Fingerprint

Cite this