The Lyman Alpha Reference Sample

Puschnig, Johannes; Hayes, Matthew; Östlin, Göran; Cannon, John; Smirnova-Pinchukova, I.; Kunth, D.; Bridge, Joanna S.; Herenz, Edmund Christian; Messa, Matteo; Oteo, I.

doi:10.1051/0004-6361/201936768

Cited by 14 publications

(10 citation statements)

References 184 publications

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“…The distribution of R CO,max /R 25 for our sample, shown in the left panel of Figure 2, has a range of 0.26−1.2, and median of 0.72. Our data thus probe out to ∼3.6 CO scale lengths (following Schruba et al 2011), thereby characterizing ∼90% of the total CO emission (Schruba et al 2011;Puschnig et al 2020). Moreover, our maps typically probe beyond radii where the rotation curve flattens out (which happens on average within 0.1 R 25 , as discussed in Section 4.4.1).…”

Section: Radial Extent Of the Co Emissionsupporting

confidence: 60%

PHANGS CO kinematics: disk orientations and rotation curves at 150 pc resolution

Lang,

Meidt,

Rosolowsky

et al. 2020

Preprint

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We present kinematic orientations and high resolution (150 pc) rotation curves for 67 main sequence star-forming galaxies surveyed in CO (2-1) emission by PHANGS-ALMA. Our measurements are based on the application of a new fitting method tailored to CO velocity fields. Our approach identifies an optimal global orientation as a way to reduce the impact of non-axisymmetric (bar and spiral) features and the uneven spatial sampling characteristic of CO emission in the inner regions of nearby galaxies. The method performs especially well when applied to the large number of independent lines-of-sight contained in the PHANGS CO velocity fields mapped at 1 resolution. The high resolution rotation curves fitted to these data are sensitive probes of mass distribution in the inner regions of these galaxies. We use the inner slope as well as the amplitude of our fitted rotation curves to demonstrate that CO is a reliable global dynamical mass tracer. From the consistency between photometric orientations from the literature and kinematic orientations determined with our method, we infer that the shapes of stellar disks in the mass range of log(M (M ))=9.0-10.9 probed by our sample are very close to circular and have uniform thickness.

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Section: Radial Extent Of the Co Emissionsupporting

confidence: 60%

PHANGS CO kinematics: disk orientations and rotation curves at 150 pc resolution

Lang,

Meidt,

Rosolowsky

et al. 2020

Preprint

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show abstract

“…Future observations of the presence of such turbulent motions (e.g. Herenz et al 2016;Puschnig et al 2020) and outflows in low-mass galaxies that are not strong LAEs could test this scenario.…”

Section: Systematic Variations In 𝑓 Escly𝛼mentioning

confidence: 98%

The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: what makes a galaxy a Lyman α emitter?

Matthee

Sobral

Hayes

et al. 2021

Monthly Notices of the Royal Astronomical Society

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We present the first results from the X-SHOOTER Lyman-α survey at z = 2 (XLS-z2). XLS-z2 is a deep spectroscopic survey of 35 Lyman-α emitters (LAEs) utilising ≈90 hours of exposure time with VLT/X-SHOOTER and covers rest-frame Lyα to Hα emission with R≈4000. We present the sample selection, the observations and the data reduction. Systemic redshifts are measured from rest-frame optical lines for 33/35 sources. In the stacked spectrum, our LAEs are characterised by an interstellar medium with little dust, a low metallicity and a high ionisation state. The ionising sources are young hot stars that power strong emission-lines in the optical and high ionisation lines in the UV. The LAEs exhibit clumpy UV morphologies and have outflowing kinematics with blue-shifted Siii absorption, a broad [O iii] component and a red-skewed Lyα line. Typically 30 per cent of the Lyα photons escape, of which one quarter on the blue side of the systemic velocity. A fraction of Lyα photons escapes directly at the systemic suggesting clear channels enabling a ≈10 per cent escape of ionising photons, consistent with an inference based on Mgii. A combination of a low effective H i column density, a low dust content and young starburst determine whether a star forming galaxy is observed as a LAE. The first is possibly related to outflows and/or a fortunate viewing angle, while we find that the latter two in LAEs are typical for their stellar mass of 109 M⊙.

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“…The dependence on the CO brightness makes α CO sensitive to varying environmental properties, such as diverse density and temperature of the molecular gas. This is even more true in ULIRGs, where starbursting regions would make the molecular gas denser and hotter, thus resulting in brighter CO emission (and thus lower α CO ; for further details, see also the Appendix in Puschnig et al 2020). We obtained α CO values in the range α CO =0.6-5.2 M pc −2 (K km s −1 ) −1 , with ∼90% of the sample (29/33 objects) having a α CO between 1.1 and 4.3 M pc −2 (K km s −1 ) −1 , i.e., the α CO usually adopted for AGN and Milky-way like galaxies, respectively.…”

Section: The Molecular Gas Contentmentioning

confidence: 99%

The molecular gas properties in local Seyfert 2 galaxies

Salvestrini,

Gruppioni,

Hatziminaoglou

et al. 2022

Preprint

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Aims. We present a multi-wavelength study of the molecular gas properties of a sample of local Seyfert 2 galaxies to assess if, and to what extent, the presence of an active galactic nucleus (AGN) can affect the Interstellar Medium (ISM) properties in a sample of 33 local Seyfert 2 galaxies. Methods. We compare the molecular gas content (M H 2 ), derived from new and archival low-J CO line measurements of a sample of AGN and a control sample of star-forming galaxies (SFGs). Both the AGN and the control sample are characterised in terms of host-galaxy properties (e.g., stellar and dust masses, M and M dust , respectively; and star formation rate, SFR). We also investigate the effect of AGN activity onto the emission of polycyclic aromatic hydrocarbon (PAH) molecules in the mid-infrared (MIR), a waveband where the dust-reprocessed emission from the obscured AGN contributes the most.Results. The AGN hosted in less massive galaxies (i.e., M < 10 10.5 M ; M dust < 10 7.5 M ) show larger molecular gas content with respect to SFGs matched in stellar and dust mass. When comparing their depletion time (t dep ∝ M H 2 /S FR), AGN show t dep ∼ 0.3−1.0 Gyr, similar to those observed in the control sample of SFGs. Seyfert 2 galaxies show fainter PAH luminosity at increasingly larger dominance of the nuclear activity in the MIR. Conclusions. We find no clear evidence for a systematic reduction of the molecular gas reservoir at galactic scale in Seyfert galaxies with respect to SFGs. This is in agreement with recent studies showing that molecular gas content only is reduced in regions of subkpc size, where the emission from the accreting supermassive black hole dominates. Nonetheless, we show that the impact of AGN activity on the ISM is clearly visible as suppression of the PAH luminosity.

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The Lyman Alpha Reference Sample

Cited by 14 publications

References 184 publications

PHANGS CO kinematics: disk orientations and rotation curves at 150 pc resolution

PHANGS CO kinematics: disk orientations and rotation curves at 150 pc resolution

The X-SHOOTER Lyman α survey at z = 2 (XLS-z2) I: what makes a galaxy a Lyman α emitter?

The molecular gas properties in local Seyfert 2 galaxies

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