Infalling gas in a Lyman-α blob

Ao, Yiping; Zheng, Zheng; Henkel, C.; Nie, Shiyu; Beelen, A.; Cen, Renyue; Dijkstra, Mark; Francis, Paul J.; Kohno, Kotaro; Lehnert, M.; Menten, K. M.; Wang, Junzhi; Weiß, A.

doi:10.1038/s41550-020-1033-3

Cited by 26 publications

(18 citation statements)

References 50 publications

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“…Wiseman et al (2017) found a rare case of inflow of metal-poor gas from the intergalactic medium onto a z = 3.35 galaxy. More recently, Ao et al (2020) report evidence of infalling gas in a Lyman-α blob at z = 2.3, and Daddi et al (2020) presented observations revealing cold gas filaments accreting toward the center of a massive group galaxy at z = 2.91. In the local Universe, a few examples of inflow activity have been found through Herschel spectroscopic observations of compact luminous infrared galaxies.…”

Section: Inflowing Gasmentioning

confidence: 99%

Close-up view of a luminous star-forming galaxy at z = 2.95

Berta

Young

Neri

et al. 2021

A&A

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Exploiting the sensitivity of the IRAM NOrthern Extended Millimeter Array (NOEMA) and its ability to process large instantaneous bandwidths, we have studied the morphology and other properties of the molecular gas and dust in the star forming galaxy, H-ATLAS J131611.5+281219 (HerBS-89a), at z = 2.95. High angular resolution (0.″3) images reveal a partial 1.″0 diameter Einstein ring in the dust continuum emission and the molecular emission lines of 12CO(9−8) and H2O(202 − 111). Together with lower angular resolution (0.″6) images, we report the detection of a series of molecular lines including the three fundamental transitions of the molecular ion OH+, namely (11 − 01), (12 − 01), and (10 − 01), seen in absorption; the molecular ion CH+(1 − 0) seen in absorption, and tentatively in emission; two transitions of amidogen (NH2), namely (202 − 111) and (220 − 211) seen in emission; and HCN(11 − 10) and/or NH(12 − 01) seen in absorption. The NOEMA data are complemented with Very Large Array data tracing the 12CO(1 − 0) emission line, which provides a measurement of the total mass of molecular gas and an anchor for a CO excitation analysis. In addition, we present Hubble Space Telescope imaging that reveals the foreground lensing galaxy in the near-infrared (1.15 μm). Together with photometric data from the Gran Telescopio Canarias, we derive a photometric redshift of zphot = 0.9−0.5+0.3 for the foreground lensing galaxy. Modeling the lensing of HerBS-89a, we reconstruct the dust continuum (magnified by a factor μ ≃ 5.0) and molecular emission lines (magnified by μ ∼ 4 − 5) in the source plane, which probe scales of ∼0.″1 (or 800 pc). The 12CO(9 − 8) and H2O(202 − 111) emission lines have comparable spatial and kinematic distributions; the source-plane reconstructions do not clearly distinguish between a one-component and a two-component scenario, but the latter, which reveals two compact rotating components with sizes of ≈1 kpc that are likely merging, more naturally accounts for the broad line widths observed in HerBS-89a. In the core of HerBS-89a, very dense gas with nH2 ∼ 107 − 9 cm−3 is revealed by the NH2 emission lines and the possible HCN(11 − 10) absorption line. HerBS-89a is a powerful star forming galaxy with a molecular gas mass of Mmol = (2.1 ± 0.4) × 1011 M⊙, an infrared luminosity of LIR = (4.6 ± 0.4) × 1012 L⊙, and a dust mass of Mdust = (2.6 ± 0.2) × 109 M⊙, yielding a dust-to-gas ratio δGDR ≈ 80. We derive a star formation rate SFR = 614 ± 59 M⊙ yr−1 and a depletion timescale τdepl = (3.4 ± 1.0) × 108 years. The OH+ and CH+ absorption lines, which trace low (∼100 cm−3) density molecular gas, all have their main velocity component red-shifted by ΔV ∼ 100 km s−1 relative to the global CO reservoir. We argue that these absorption lines trace a rare example of gas inflow toward the center of a galaxy, indicating that HerBS-89a is accreting gas from its surroundings.

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Section: Inflowing Gasmentioning

confidence: 99%

Close-up view of a luminous star-forming galaxy at z = 2.95

Berta

Young

Neri

et al. 2021

A&A

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“…Essentially every simulation of galaxy formation (Faucher-Giguère et al 2010) predicts that gaseous accretion is also important -particularly at high redshifts (z > ∼ 2) -and this has focused attention on systems in which a double Lyα profile with a blue-dominant peak is observed, often cited as evidence for on-going accretion of cool gas (e.g., Vanzella et al 2017;Martin et al 2014Martin et al , 2016Ao et al 2020). Quantitative predictions of Lyα emission from accreting baryons depend sensitively on the thermal state and the small-scale structure of the gas (e.g., Kollmeier et al 2010;Faucher-Giguère et al 2010;Goerdt et al 2010), leading to large uncertainties in the predictions.…”

Section: Introductionmentioning

confidence: 99%

The KBSS–KCWI survey: the connection between extended Ly α haloes and galaxy azimuthal angle at z ∼ 2–3

Chen

Steidel

Erb

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the first statistical analysis of kinematically-resolved, spatially-extended Lyα emission around z = 2 − 3 galaxies in the Keck Baryonic Structure Survey (KBSS) using the Keck Cosmic Web Imager (KCWI). Our sample of 59 star-forming galaxies (z med = 2.29) comprises the subset with typical KCWI integration times of ∼ 5 hours and with existing imaging data from the Hubble Space Telescope and/or adaptive optics-assisted integral field spectroscopy. The high resolution images were used to evaluate the azimuthal dependence of the diffuse Lyα emission with respect to the stellar continuum within projected galactocentric distances of 30 proper kpc. We introduce cylindrically-projected 2D spectra (CP2D) that map the averaged Lyα spectral profile over a specified range of azimuthal angle, as a function of impact parameter around galaxies. The averaged CP2D spectrum of all galaxies shows clear signatures of Lyα resonant scattering by outflowing gas. We stacked the CP2D spectra of individual galaxies over ranges of azimuthal angle with respect to their major axes. The extended Lyα emission along the galaxy principal axes are statistically indistinguishable, with residual asymmetry of ≤ 2% (∼ 2σ) of the integrated Lyα emission. The symmetry implies that the Lyα scattering medium is dominated by outflows in all directions within 30 kpc. Meanwhile, we find that the blueshifted component of Lyα emission is marginally stronger along galaxy minor axes for galaxies with relatively weak Lyα emission. We speculate that this weak directional dependence of Lyα emission becomes discernible only when the Lyα escape fraction is low. These discoveries highlight the need for similar analyses in simulations with Lyα radiative transfer modeling.

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“…The bright Lyα emission has been imputed to photoionization from active galactic nuclei (AGN; Geach et al 2009) to fluorence and reflection of the light from an embedded quasar (Cantalupo et al 2012(Cantalupo et al , 2014; to integrated emission from star-forming satellite galaxies or to material spread in the circum-galactic medium by galactic winds (see, e.g., Steidel et al 2011); to shock heating of the gas via galactic superwinds (Taniguchi & Shioya 2000); and to cooling from cold accretion (Haiman et al 2000;Fumagalli et al 2014;Trebitsch et al 2016). Furthermore, Lyα photons are likely affected by complex radiative transfer effects, at least on small scales (<10 kpc) where resonant scattering seems to be important (e.g., Ao et al 2020).…”

Section: Introductionmentioning

confidence: 99%

A search for dust and molecular gas in enormous Lyαnebulae atz≈ 2

Decarli¹,

Battaia

Walter

et al. 2020

A&A

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Enormous Lyα nebulae, extending over 300−500 kpc around quasars, represent the pinnacle of galaxy and cluster formation. Here we present IRAM Plateau de Bure Interferometer observations of the enormous Lyα nebulae “Slug” (z = 2.282) and “Jackpot” (z = 2.041). Our data reveal bright, synchrotron emission associated with the two radio-loud active galactic nuclei embedded in the targeted nebulae as well as molecular gas, as traced via the CO(3−2) line, in three galaxies (two sources in Slug, and one in Jackpot). All of the CO emission is associated with galaxies detected in their rest-frame UV stellar emission. The total mass in molecular gas of these three galaxies [∼(3 − 5) × 1010 M⊙] is comparable with the total ionized gas mass responsible for the diffuse nebular emission. Our observations place limits on the molecular gas emission in the nebulae: the molecular gas surface density is ΣH2 < 12 − 25 M⊙ pc−2 for the Slug nebula and ΣH2 < 34 − 68 M⊙ pc−2 for the Jackpot nebula. These are consistent with the expected molecular gas surface densities, as predicted via photoionization models of the rest-frame UV line emission in the nebulae, and via Lyα absorption in the Jackpot nebula. Compared to other radio-loud quasars at z > 1 and high-redshift radio-loud galaxies, we do not find any strong trends relating the molecular gas reservoirs, the radio power, and the Lyα luminosities of these systems. The significant step in sensitivity required to achieve a detection of the molecular gas from the nebulae, if present, will require a substantial time investment with JVLA, NOEMA, or ALMA.

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Infalling gas in a Lyman-α blob

Cited by 26 publications

References 50 publications

Close-up view of a luminous star-forming galaxy at z = 2.95

Close-up view of a luminous star-forming galaxy at z = 2.95

The KBSS–KCWI survey: the connection between extended Ly α haloes and galaxy azimuthal angle at z ∼ 2–3

A search for dust and molecular gas in enormous Lyαnebulae atz≈ 2

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