Spitzer’s perspective of polycyclic aromatic hydrocarbons in galaxies

Li, Aigen

doi:10.1038/s41550-020-1051-1

Cited by 160 publications

(103 citation statements)

References 178 publications

(289 reference statements)

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“…Potential building blocks that did not participate in water chemistry were excluded. This scenario explains the exclusion of various molecules from extant biochemistry, such as polycyclic aromatic hydrocarbons, which are highly abundant in the abiotic universe (Hertzog et al 2019 ; Li 2020 ), but do not react with water.…”

Section: Discussionmentioning

confidence: 99%

Water and Life: The Medium is the Message

et al. 2021

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Water, the most abundant compound on the surface of the Earth and probably in the universe, is the medium of biology, but is much more than that. Water is the most frequent actor in the chemistry of metabolism. Our quantitation here reveals that water accounts for 99.4% of metabolites in Escherichia coli by molar concentration. Between a third and a half of known biochemical reactions involve consumption or production of water. We calculated the chemical flux of water and observed that in the life of a cell, a given water molecule frequently and repeatedly serves as a reaction substrate, intermediate, cofactor, and product. Our results show that as an E. coli cell replicates in the presence of molecular oxygen, an average in vivo water molecule is chemically transformed or is mechanistically involved in catalysis ~ 3.7 times. We conclude that, for biological water, there is no distinction between medium and chemical participant. Chemical transformations of water provide a basis for understanding not only extant biochemistry, but the origins of life. Because the chemistry of water dominates metabolism and also drives biological synthesis and degradation, it seems likely that metabolism co-evolved with biopolymers, which helps to reconcile polymer-first versus metabolism-first theories for the origins of life.

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Section: Discussionmentioning

confidence: 99%

Water and Life: The Medium is the Message

et al. 2021

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“…Detailed Spitzer IRS spectra of hundreds of galaxies with AGN activity found that some PAH features are seen in most cases, 146 showing that PAHs can survive in some of these environments. Li 147 summarized the PAH observations in AGN by noting that the 6.2, 7.7, and 8.6 μm PAH features, although suppressed with respect to the 11.3 μm band (perhaps because smaller PAHs are more susceptible to the hard radiation field of an AGN) nevertheless can be present. Figure 5 in Ref.…”

Section: Gep-i Redshift Measurementsmentioning

confidence: 99%

“…Other physical effects will also influence the strengths of these mid-IR PAHs features, for example, low metallicity in high-z, young galaxies, or destructive supernovae activity. 147 Although weak PAH features make photometric redshift measurements more challenging, it is precisely the complexity and variability of these features that ultimately enable diagnosis of the physical conditions present.…”

Section: Gep-i Redshift Measurementsmentioning

confidence: 99%

Galaxy Evolution Probe

Glenn

Bradford

Rosolowsky

et al. 2021

J. Astron. Telesc. Instrum. Syst.

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The Galaxy Evolution Probe (GEP) is a concept for a mid-and far-infrared space observatory to measure key properties of large samples of galaxies with large and unbiased surveys. GEP will attempt to achieve zodiacal light and Galactic dust emission photon backgroundlimited observations by utilizing a 6-K, 2.0-m primary mirror and sensitive arrays of kinetic inductance detectors (KIDs). It will have two instrument modules: a 10 to 400 μm hyperspectral imager with spectral resolution R ¼ λ∕Δλ ≥ 8 (GEP-I) and a 24 to 193 μm, R ¼ 200 grating spectrometer (GEP-S). GEP-I surveys will identify star-forming galaxies via their thermal dust emission and simultaneously measure redshifts using polycyclic aromatic hydrocarbon emission lines. Galaxy luminosities derived from star formation and nuclear supermassive black hole accretion will be measured for each source, enabling the cosmic star formation history to be measured to much greater precision than previously possible. Using optically thin far-infrared fine-structure lines, surveys with GEP-S will measure the growth of metallicity in the hearts of galaxies over cosmic time and extraplanar gas will be mapped in spiral galaxies in the local universe to investigate feedback processes. The science case and mission architecture designed to meet the science requirements is described, and the KID and readout electronics state of the art and needed developments are described. This paper supersedes the GEP concept study report cited in it by providing new content, including: a summary of recent mid-infrared KID development, a discussion of microlens array fabrication for mid-infrared KIDs, and additional context for galaxy surveys. The reader interested in more technical details may want to consult the concept study report. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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“…These forces bring SP3-bond. In interstellar space, central star can do such illumination on cosmic dust 29) . By photoionization, angle of 1C-0C-2C varies from 94.7 to 95.4 degree.…”

Section: S Sp Pi In N S St Ta At Te E a An Na Al Ly Ys Si Is Smentioning

confidence: 99%

Void-Defect Induced Magnetism and Structure Change of Carbon Material-Ⅲ: Hydrocarbon Molecules

Ota

Nemes

2021

J. Magn. Soc. Jpn.

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Void-defect induced magnetism of graphene molecule was recently reported in our previous paper of this series study. This paper investigated the case of hydrogenated graphene molecule, in chemical term, polycyclic aromatic hydrocarbon (PAH). Molecular infrared spectrum obtained by density functional theory was compared with astronomical observation. Void-defect on PAH caused serious structure change. Typical example of C23H12 had two carbon pentagon rings among hexagon networks. Stable spin state was non-magnetic singlet state. This is contrary to pure carbon case of C23, which show magnetic triplet state. It was discussed that Hydrogen played an important role to diminish magnetism by creating an SP3-bond among SP2-networks. Such a structure change affected molecular vibration and finally to photoemission spectrum in infrared region. The dication-C23H12 showed featured bands at 3.2, 6.3, 7.7, 8.6, 11.2, and 12.7 micrometer. It was surprising that those calculated bands coincided well with astronomically observed bands in many planetary nebulae. To confirm our study, large size molecule of C53H18 was studied. Calculation reproduced again similar astronomical bands. Also, small size molecule of C12H8 showed good coincidence with the spectrum observed for young stars. This paper would be the first report to indicate the specific PAH in space.

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Spitzer’s perspective of polycyclic aromatic hydrocarbons in galaxies

Cited by 160 publications

References 178 publications

Water and Life: The Medium is the Message

Water and Life: The Medium is the Message

Galaxy Evolution Probe

Void-Defect Induced Magnetism and Structure Change of Carbon Material-Ⅲ: Hydrocarbon Molecules

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