[N ii] Fine-structure Emission at 122 and 205 μm in a Galaxy at z = 2.6: A Globally Dense Star-forming Interstellar Medium

Doherty, M.; Ivison, R. J.; Dye, S.

doi:10.3847/1538-4357/abc5b9

Cited by 9 publications

(10 citation statements)

References 78 publications

(98 reference statements)

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“…We use Splatalogue (Remĳan et al 2007) to identify emission lines in the total spectrum. CO 𝐽 = 5 → 4 at 𝜈 obs = 162.133 GHz is detected at high significance as expected, and exhibits the characteristic double horned profile as other molecular and atomic lines (Geach et al 2015(Geach et al , 2018Harrington et al 2019;Doherty et al 2020), and well-modelled in the source-plane reconstruction by a rotating disc (Geach et al 2018). We also detect a fainter, but sig-nificant, emission feature at 𝜈 obs = 161.072 GHz that is consistent with the redshifted ground state ortho-NH 3 𝐽 𝐾 = 1 0 → 0 0 rotational line at 𝜈 rest = 572.498 GHz (Cazzoli et al 2009, hereafter we refer to the line as NH 3 ).…”

Section: Resultssupporting

confidence: 74%

“…As can be seen from Figure 1, the scaled CO(5-4) emission is an excellent description of the NH 3 line emission. In turn, the line profile of the integrated, projected CO emission is well modelled by a nearly edge-on rotating disc (when modelled in the source plane and projected into the image plane) and this profile is shared by the majority of detected lines within this system covering a wide range of conditions, from the relatively low density molecular reservoir traced by C (1-0) to the warmer, dense, ionised gas traced by N + (Su et al 2017;Geach et al 2018;Harrington et al 2019;Doherty et al 2020). The striking similarity in the observed line profiles imply that the observed NH 3 emission is broadly co-located with the COemitting gas, likely emanating from discrete sites of on-going star formation scattered throughout the gas-rich disc.…”

Section: Discussionmentioning

confidence: 83%

“…Mergers undoubtedly play a role in the triggering high-z starbursts (Tacconi et al 2010;Engel et al 2010), but there is some observational evidence that some of the most intensely star-forming galaxies are simply consistent with large gas-dominated rotationally supported discs (Hodge et al 2016;Jiménez-Andrade et al 2018;Geach et al 2018;Gullberg et al 2018). In these systems a significant fraction of the ISM appears to have been driven to high density (Oteo et al 2017;Geach et al 2018;Doherty et al 2020), possibly via violent disc instabilities (VDIs, e.g. Toomre 1964;Dekel et al 2009b,a), and in this case the extreme star formation rates measured can naturally be explained by the sheer quantity of gas available for active participation in star formation .…”

Section: Introductionmentioning

confidence: 99%

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Ammonia in the interstellar medium of a starbursting disc at z = 2.6

Doherty

Ivison

Menten

et al. 2022

Monthly Notices of the Royal Astronomical Society: Letters

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We report the detection of the ground state rotational emission of ammonia, ortho-NH3 (JK = 10 → 00) in a gravitationally lensed, intrinsically hyperluminous, star-bursting galaxy at z = 2.6. The integrated line profile is consistent with other molecular and atomic emission lines which have resolved kinematics well-modelled by a 5 kpc-diameter rotating disc. This implies that the gas responsible for NH3 emission is broadly tracing the global molecular reservoir, but likely distributed in pockets of high density (n ≳ 5 × 104 cm−3). With a luminosity of 2.8 × 106 L⊙, the NH3 emission represents 2.5 × 10−7 of the total infrared luminosity of the galaxy, comparable to the ratio observed in the Kleinmann-Low nebula in Orion and consistent with sites of massive star formation in the Milky Way. If $L_{\rm NH_3}/L_{\rm IR}$ serves as a proxy for the ‘mode’ of star formation, this hints that the nature of star formation in extreme starbursts in the early Universe is similar to that of Galactic star-forming regions, with a large fraction of the cold interstellar medium in this state, plausibly driven by a storm of violent disc instabilities in the gas-dominated disc. This supports the ‘full of Orions’ picture of star formation in the most extreme galaxies seen close to the peak epoch of stellar mass assembly.

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Section: Resultssupporting

confidence: 74%

Section: Discussionmentioning

confidence: 83%

Section: Introductionmentioning

confidence: 99%

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Ammonia in the interstellar medium of a starbursting disc at z = 2.6

Doherty

Ivison

Menten

et al. 2022

Monthly Notices of the Royal Astronomical Society: Letters

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“…We traced this part to source plane using the best-fit model above, the corresponding source located in the northeast of the main source as shown in Figure 4 which suggests it is an extra individual component. S2 is also de-tected in ALMA [NII] 205 µm (data from Geach et al 2018) and described in (Doherty et al 2020). While this study failed to identify the detection with a second source, we confirm the presence of S2 at the same redshift as S1 through a combination of HST/WFC3 and [NII] observations.…”

Section: Second Lensed Sourcesupporting

confidence: 55%

Massive molecular gas reservoir in a luminous sub-millimeter galaxy during cosmic noon

Liu,

Chartab,

Nayyeri

et al. 2021

Preprint

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We present multi-band observations of an extremely dusty star-forming lensed galaxy (HERS1) at z = 2.553. High-resolution maps of HST /WFC3, SMA, and ALMA show a partial Einsteinring with a radius of ∼3 . The deeper HST observations also show the presence of a lensing arc feature associated with a second lens source, identified to be at the same redshift as the bright arc based on a detection of the [NII] 205µm emission line with ALMA. A detailed model of the lensing system is constructed using the high-resolution HST/WFC3 image, which allows us to study the source plane properties and connect rest-frame optical emission with properties of the galaxy as seen in sub-millimeter and millimeter wavelengths. Corrected for lensing magnification, the spectral energy distribution fitting results yield an intrinsic star formation rate of about 1000 ± 260 M yr −1 , a stellar mass M * = 4.3 +2.2 −1.0 × 10 11 M , and a dust temperature T d = 35 +2 −1 K. The intrinsic CO emission line (J up = 3, 4, 5, 6, 7, 9) flux densities and CO spectral line energy distribution are derived based on the velocity-dependent magnification factors. We apply a radiative transfer model using the large velocity gradient method with two excitation components to study the gas properties. The low-excitation component has a gas density n H2 = 10 3.1±0.6 cm −3 and kinetic temperature T k = 19 +7 −5 K and a high-excitation component has n H2 = 10 2.8±0.3 cm −3 and T k = 550 +260 −220 K. Additionally, HERS1 has a gas fraction of about 0.4 ± 0.2 and is expected to last 250 Myr. These properties offer a detailed view of a typical sub-millimeter galaxy during the peak epoch of star-formation activity.

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“…Although we consider specifically the line ratio of [O III ]52/88 in this study, other pairs such as [N II ] lines at 122 and 205 µm (e.g. Zhao et al 2016;Doherty et al 2020) can also be the density indicator (see also Section 5.1). Far-infrared fine structure lines are useful to observationally study the density structure of high-redshift galaxies, in which the inside-out quenching driven by massive BHs can be occuring.…”

Section: [O III ] Line Modelmentioning

confidence: 99%

Capturing the inside-out quenching by black holes with far-infrared atomic line ratios

Inoue,

Matsuo,

Yoshida

et al. 2021

Preprint

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We propose to use relative strengths of far-infrared fine structure lines from galaxies to characterise early phases of the inside-out quenching by massive black holes (BHs). The BH feedback is thought to quench star formation by evacuating the ambient gas. In order to quantify the feedback effect on the gas density in the galactic centres, we utilise the outputs of IllustrisTNG and Illustris simulations, which implement different BH feedback models. We devise a physical model of H II regions and compute the intensities of [O III ] 52 and 88 µm lines. The line intensity ratio is sensitive to the local electron density, and thus can be used to measure the strength and physical extent of the BH quenching. If the BH feedback abruptly operates and expel the gas when it grows to a certain mass, as modelled in IllustrisTNG, the low-density gas yields relatively weak [O III ] 52 line with respect to 88 µm. In contrast, if the feedback strength and hence the local gas density are not strongly correlated with the BH mass, as in Illustris, the line ratio is not expected to vary significantly among galaxies with different evolutionary stages. We find these features are reproduced in the simulations. We also show that the line ratios are not sensitive to the aperture size for measurement, and thus observations do not need to resolve the galactic centres. We argue that the integrated line ratios can be used to capture the onset of the inside-out quenching by BHs.

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[N ii] Fine-structure Emission at 122 and 205 μm in a Galaxy at z = 2.6: A Globally Dense Star-forming Interstellar Medium

Cited by 9 publications

References 78 publications

Ammonia in the interstellar medium of a starbursting disc at z = 2.6

Ammonia in the interstellar medium of a starbursting disc at z = 2.6

Massive molecular gas reservoir in a luminous sub-millimeter galaxy during cosmic noon

Capturing the inside-out quenching by black holes with far-infrared atomic line ratios

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