First extragalactic detection of a phosphorus-bearing molecule with ALCHEMI: Phosphorus nitride (PN)

Haasler, D.; Rivilla, V. M.; Martín, S.; Holdship, Jonathan; Viti, S.; Harada, Nanase; Mangum, J. G.; Sakamoto, Kazushi; Müller, S.; Tanaka, K.; Yoshimura, Yuki; Nakanishi, Koji; Colzi, L.; Hunt, L. K.; Emig, K. L.; Aladro, R.; Humire, P. K.; Henkel, C.; Werf, P. van der

doi:10.1051/0004-6361/202142032

Cited by 25 publications

(11 citation statements)

References 63 publications

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“…In molecular clouds and starforming regions, only PN and PO have been identified in different environments (Turner and Bally 1987;Ziurys 1987;Fontani et al, 2016Fontani et al, , 2019Lefloch et al, 2016;Rivilla et al, 2016;Rivilla et al, 2018Rivilla et al, , 2020aBergner et al, 2019;Bernal et al, 2021). Recently, PN has been detected toward molecular cloud complexes within the central region of the starburst galaxy NCG 253 (Haasler et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

Ionize Hard: Interstellar PO+ Detection

Rivilla

Concepción

Jiménez-Serra

et al. 2022

Front. Astron. Space Sci.

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We report the first detection of the phosphorus monoxide ion (PO+) in the interstellar medium. Our unbiased and very sensitive spectral survey toward the G+0.693–0.027 molecular cloud covers four different rotational transitions of this molecule, two of which (J = 1–0 and J = 2–1) appear free of contamination from other species. The fit performed, assuming local thermodynamic equilibrium conditions, yields a column density of N=(6.0 ± 0.7) × 1011 cm−2. The resulting molecular abundance with respect to molecular hydrogen is 4.5 × 10–12. The column density of PO+ normalized by the cosmic abundance of P is larger than those of NO+ and SO+, normalized by N and S, by factors of 3.6 and 2.3, respectively. The N(PO+)/N(PO) ratio is 0.12 ± 0.03, more than one order of magnitude higher than that of N(SO+)/N(SO) and N(NO+)/N(NO). These results indicate that P is more efficiently ionized than N and S in the ISM. We have performed new chemical models that confirm that the PO+ abundance is strongly enhanced in shocked regions with high values of cosmic-ray ionization rates (10–15 − 10–14 s−1), as occurring in the G+0.693–0.027 molecular cloud. The shocks sputter the interstellar icy grain mantles, releasing into the gas phase most of their P content, mainly in the form of PH3, which is converted into atomic P, and then ionized efficiently by cosmic rays, forming P+. Further reactions with O2 and OH produces PO+. The cosmic-ray ionization of PO might also contribute significantly, which would explain the high N(PO+)/N(PO) ratio observed. The relatively high gas-phase abundance of PO+ with respect to other P-bearing species stresses the relevance of this species in the interstellar chemistry of P.

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Section: Introductionmentioning

confidence: 99%

Ionize Hard: Interstellar PO+ Detection

Rivilla

Concepción

Jiménez-Serra

et al. 2022

Front. Astron. Space Sci.

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“…This paper is one in a series of ALCHEMI projects that analyzes the conditions in the NGC 253 CMZ using molecular signatures (Martín et al 2021;Harada et al 2021;Holdship et al 2021;Haasler et al 2022;Holdship et al 2022;Humire et al 2022). Additionally, in this paper we explore how molecular emission can trace heating processes associated with star formation in this active environment.…”

Section: Introductionmentioning

confidence: 99%

Tracing Interstellar Heating: An ALCHEMI Measurement of the HCN Isomers in NGC 253

Behrens

Mangum

Holdship

et al. 2022

ApJ

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We analyze HCN and HNC emission in the nearby starburst galaxy NGC 253 to investigate its effectiveness in tracing heating processes associated with star formation. This study uses multiple HCN and HNC rotational transitions observed using the Atacama Large Millimeter/submillimeter Array via the ALCHEMI Large Program. To understand the conditions and associated heating mechanisms within NGC 253's dense gas, we employ Bayesian nested sampling techniques applied to chemical and radiative transfer models, which are constrained using our HCN and HNC measurements. We find that the volume density n H 2 and cosmic-ray ionization rate (CRIR) ζ are enhanced by about an order of magnitude in the galaxy’s central regions as compared to those further from the nucleus. In NGC 253's central giant molecular clouds (GMCs), where observed HCN/HNC abundance ratios are the lowest, n ∼ 105.5 cm−3 and ζ ∼ 10−12 s−1 (greater than 104 times the average Galactic rate). We find a positive correlation in the association of both density and CRIR with the number of star formation-related heating sources (supernova remnants, H ii regions, and super hot cores) located in each GMC, as well as a correlation between CRIRs and supernova rates. Additionally, we see an anticorrelation between the HCN/HNC ratio and CRIR, indicating that this ratio will be lower in regions where ζ is higher. Though previous studies suggested HCN and HNC may reveal strong mechanical heating processes in NGC 253's CMZ, we find cosmic-ray heating dominates the heating budget, and mechanical heating does not play a significant role in the HCN and HNC chemistry.

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“…The nuclear region of NGC 253 is a chemically rich environment (Krieger et al 2020a;Martín et al 2021;Haasler et al 2022) and hosts a number of massive, dense molecular clouds (e.g., Sakamoto et al 2011;Leroy et al 2015a), radio continuum sources (likely H II regions and supernova remnants; Turner & Ho 1985;Watson et al 1996;Ulvestad & Antonucci 1997;Kornei & McCrady 2009), and masers (e.g., Gorski et al 2017Gorski et al , 2019Humire et al 2022). The overwhelming majority of the star formation in the nuclear starburst is concentrated in massive forming "super" star clusters (SSCs; Ando et al 2017;Leroy et al 2018;Rico-Villas et al 2020;Mills et al 2021;Levy et al 2021).…”

Section: Introductionmentioning

confidence: 99%

The Morpho-kinematic Architecture of Super Star Clusters in the Center of NGC 253

Levy

Bolatto

Leroy

et al. 2022

ApJ

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The center of the nearby galaxy NGC 253 hosts a population of more than a dozen super star clusters (SSCs) that are still in the process of forming. The majority of the star formation of the burst is concentrated in these SSCs, and the starburst is powering a multiphase outflow from the galaxy. In this work, we measure the 350 GHz dust continuum emission toward the center of NGC 253 at 47 mas (0.8 pc) resolution using data from the Atacama Large Millimeter/submillimeter Array. We report the detection of 350 GHz (dust) continuum emission in the outflow for the first time, associated with the prominent South-West streamer. In this feature, the dust emission has a width of ≈8 pc, is located at the outer edge of the CO emission, and corresponds to a molecular gas mass of ∼(8–17)×106 M ⊙. In the starburst nucleus, we measure the resolved radial profiles, sizes, and molecular gas masses of the SSCs. Compared to previous work at the somewhat lower spatial resolution, the SSCs here break apart into smaller substructures with radii 0.4–0.7 pc. In projection, the SSCs, dust, and dense molecular gas appear to be arranged as a thin, almost linear, structure roughly 155 pc in length. The morphology and kinematics of this structure can be well explained as gas following x 2 orbits at the center of a barred potential. We constrain the morpho-kinematic arrangement of the SSCs themselves, finding that an elliptical, angular-momentum-conserving ring is a good description of both the morphology and kinematics of the SSCs.

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First extragalactic detection of a phosphorus-bearing molecule with ALCHEMI: Phosphorus nitride (PN)

Cited by 25 publications

References 63 publications

Ionize Hard: Interstellar PO+ Detection

Ionize Hard: Interstellar PO+ Detection

Tracing Interstellar Heating: An ALCHEMI Measurement of the HCN Isomers in NGC 253

The Morpho-kinematic Architecture of Super Star Clusters in the Center of NGC 253

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