Low gas-phase metallicities of ultraluminous infrared galaxies are a result of dust obscuration

Chartab, Nima; Cooray, Asantha; Ma, Jingzhe; Nayyeri, Hooshang; Zilliot, Preston; Lopez, J. A.; Fadda, D.; Herrera-Camus, Rodrigo; Malkan, Matthew A.; Rigopoulou, D.; Sheth, Kartik; Wardlow, J. L.

doi:10.1038/s41550-022-01679-y

Cited by 13 publications

(4 citation statements)

References 78 publications

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“…Bernard-Salas et al 2009), the derived Ar and Ne abundance corresponds to 0.62-0.79 times the solar value (assuming the solar Ar/H and Ne/H derived in Asplund et al 2021). This metallicity is lower than the range generally observed in U/LIRGs (Rupke et al 2008;Pereira-Santaella et al 2017b;Chartab et al 2022).…”

Section: Discussioncontrasting

confidence: 55%

Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H₂O and CO

García-Bernete,

Pereira-Santaella,

González-Alfonso

et al. 2024

A&A

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We analyze JWST NIRSpec$+$MIRI/MRS observations of the infrared (IR) gas-phase molecular bands of the most enshrouded source (D1) within the interacting system and luminous IR galaxy II\,Zw\,096. We report the detection of rovibrational lines of H$_2$O $ (sim 5.3-7.2 mu m) and 12CO nu =1-0 (sim 4.45-4.95 mu m) in D1. The CO band shows the R- and P-branches in emission and the spectrum of the H$_2$O band shows the P-branch in emission and the R-branch in absorption. The H$_2$O R-branch in absorption unveils an IR-bright embedded compact source in D1 and the CO broad component features a highly turbulent environment. From both bands, we also identified extended intense star-forming (SF) activity associated with circumnuclear photodissociation regions (PDRs), consistent with the strong emission of the ionised 7.7 mu m polycyclic aromatic hydrocarbon band in this source. By including the 4.5-7.0 mu m continuum information derived from the H$_2$O and CO analysis, we modelled the IR emission of D1 with a dusty torus and SF component. The torus is very compact (diameter of sim 3\,pc at 5 mu m) and characterised by warm dust (sim 370\,K), giving an IR surface brightness of sim 3.6times 108\,L$_ This result suggests the presence of a dust-obscured active galactic nucleus (AGN) in D1, which has an exceptionally high covering factor that prevents the direct detection of AGN emission. Our results open a new way to investigate the physical conditions of inner dusty tori via modelling the observed IR molecular bands.

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Section: Discussioncontrasting

confidence: 55%

Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H₂O and CO

García-Bernete,

Pereira-Santaella,

González-Alfonso

et al. 2024

A&A

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“…The ISM in the Milky Way has regions with different metallicities (De Cia et al 2021) and strengths of dust depletion (Jenkins 2009;Welty et al 2020). Variations in metallicities (Sánchez Almeida et al 2015;Kreckel et al 2019;Wang et al 2022;Chartab et al 2022) and dust depletion (Prochaska 2003;Dessauges-Zavadsky et al 2006;Rodríguez et al 2006;Wiseman et al 2017;de Ugarte Postigo et al 2018;Noterdaeme et al 2017;Guber et al 2018;Ramburuth-Hurt et al 2023) have been observed within external galaxies as well. It is well possible that the total line of sight towards a star intercepts gases with different chemical properties.…”

Section: A Mixture Of Different Ism Gas Typesmentioning

confidence: 97%

α-element enhancements in the ISM of the LMC and SMC: Evidence of recent star formation

De Cia,

Roman-Duval,

Konstantopoulou

et al. 2024

A&A

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Important questions regarding the chemical composition of the neutral interstellar medium (ISM) in the Large Magellanic Cloud (LMC) and Small Magellanic Cloud (SMC) are still open. It is usually assumed that their metallicity is uniform and equal to that measured in hot stars and regions, but direct measurements of the neutral ISM metallicity had not been performed until now. Deriving the metallicity from the observed metal abundances is not straightforward because the abundances depend on the depletion of metals into dust and on nucleosynthesis effects such as alpha -element enhancement. Our aim is to measure the metallicity of the neutral ISM in the LMC and SMC, dust depletion, and any nucleosynthesis effects. We collected literature column densities of and in the neutral ISM towards 32 hot stars in the LMC and $22$ in the SMC. We determined dust depletion from the relative abundances of different metals because they deplete with different strengths. This includes a `golden sample' of sightlines where Ti and other alpha -elements are available. We fit linear relations to the observed abundance patterns so that the slopes determined the strengths of dust depletion and the normalizations determined the metallicities. We investigated alpha -element enhancements in the gas from the deviations from the linear fits and compared them with stars. In our golden sample we find alpha -element enhancement in the neutral ISM in most systems, on average 0.26 dex (0.35 dex) for the LMC (SMC), and an Mn underabundance in the SMC (on average $-0.35$ dex). Measurements of are not available for the LMC. These are higher than for stars at similar metallicities. We find total neutral ISM metallicities that are mostly consistent with hot star metallicity values, on average $M$/H tot =-0.33$ ($-0.83$), with standard deviations of 0.30 (0.30), in the LMC (the SMC). In six systems, however, we find significantly lower metallicities, 2 out of 32 in the LMC (with $ solar) and 4 out of 22 in the SMC (3<!PCT!>\ and 10<!PCT!> solar), two of which are in the outskirts of the SMC near the Magellanic Bridge, a region known for having a lower metallicity. The observed alpha -element enhancements and Mn underabundance are likely due to bursts of star formation, more recently than $ Gyr ago, that enriched the ISM from core-collapse supernovae. With the exception of lines of sight towards the Magellanic Bridge, the neutral gas in the LMC and SMC appears fairly well mixed in terms of metallicity.

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“…We do not vary, however, relative elemental abundances, and assume the default gas-phase values provided by Cloudy for the ISM (log(N/O) = −0.6), with the default grains and polycyclic aromatic hydrocarbons (PAH) size distribution from Abel et (2008). We note that some relative elemental abundances, specifically the N/O ratio, due to the secondary nature of nitrogen production in stellar evolution, depend on the overall, absolute metallicity (e.g., O/H) of the gas, especially at values below 0.25 Z (Nicholls et al 2017;Chartab et al 2022). However, as we subsequently see, the best-fit metallicity for W2246-0526 is 0.5 Z , still sufficiently high for relative abundances not to be a dominant factor in the models.…”

Section: Ism Modelsmentioning

confidence: 99%

A benchmark for extreme conditions of the multiphase interstellar medium in the most luminous hot dust-obscured galaxy at z = 4.6

Fernández Aranda,

Díaz Santos,

Hatziminaoglou

et al. 2024

A&A

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WISE J224607.6--052634.9 (W2246--0526) is a hot dust-obscured galaxy at $z$ = 4.601, and the most luminous obscured quasar known to date. W2246--0526 harbors a heavily obscured supermassive black hole that is most likely accreting above the Eddington limit. We present observations with the Atacama Large Millimeter/submillimeter Array (ALMA) in seven bands, including band 10, of the brightest far-infrared (FIR) fine-structure emission lines of this galaxy: OI m OIII m NII m OI m CII m NII m CI m $, and CI m $. A comparison of the data to a large grid of Cloudy radiative transfer models reveals that a high hydrogen density ($n_ H $) and extinction ($A_ V mag), together with extreme ionization ($log(U)=-0.5$) and a high X-ray to UV ratio ($ ox are required to reproduce the observed nuclear line ratios. The values of $ ox $ and $U$ are among the largest found in the literature and imply the existence of an X-ray-dominated region (XDR). In fact, this component explains the a priori very surprising non-detection of the OIII m $ emission line, which is actually suppressed, instead of boosted, in XDR environments. Interestingly, the best-fitted model implies higher X-ray emission and lower CO content than what is detected observationally, suggesting the presence of a molecular gas component that should be further obscuring the X-ray emission over larger spatial scales than the central region that is being modeled. These results highlight the need for multiline infrared observations to characterize the multiphase gas in high redshift quasars and, in particular, W2246--0526 serves as an extreme benchmark for comparisons of interstellar medium conditions with other quasar populations at cosmic noon and beyond.

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Low gas-phase metallicities of ultraluminous infrared galaxies are a result of dust obscuration

Cited by 13 publications

References 78 publications

Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H₂O and CO

Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H₂O and CO

α-element enhancements in the ISM of the LMC and SMC: Evidence of recent star formation

A benchmark for extreme conditions of the multiphase interstellar medium in the most luminous hot dust-obscured galaxy at z = 4.6

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Low gas-phase metallicities of ultraluminous infrared galaxies are a result of dust obscuration

Cited by 13 publications

References 78 publications

Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H2O and CO

Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H2O and CO

α-element enhancements in the ISM of the LMC and SMC: Evidence of recent star formation

A benchmark for extreme conditions of the multiphase interstellar medium in the most luminous hot dust-obscured galaxy at z = 4.6

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Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H₂O and CO

Structures Of Dust and gAs (SODA): Constraining the innermost dust properties of II Zw96 with JWST observations of H₂O and CO