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Nakashima H, Nakatsuji H. Potential Energy Curves of the Low-Lying Five 1Σ + and 1Π States of a CH + Molecule Based on the Free Complement - Local Schrödinger Equation Theory and the Chemical Formula Theory. J Chem Theory Comput 2023; 19:6733-6744. [PMID: 37706317 DOI: 10.1021/acs.jctc.3c00645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/15/2023]
Abstract
The potential energy curves (PECs) of the low-lying five 1Σ+ and 1Π states (X1Σ+, C1Σ+, 31Σ+, A1Π, and D1Π states) of a CH+ molecule, an important interstellar molecule, were calculated by the free complement (FC) - local Schrödinger equation (LSE) theory with the direct local sampling scheme. The FC wave functions were constructed based on the chemical formula theory (CFT), whose local characters correspond to the covalent dissociations: C+(2P°(s2p))) + H(2S) of the X1Σ+ and A1Π states and the ionic dissociations: C(1D(s2p2)) + H+ of the C1Σ+ and D1Π states. All the calculated PECs were obtained with satisfying the chemical accuracy, i.e., error less than 1 kcal/mol, as absolute total energy of the Schrödinger equation without any energy shift. The spectroscopic data calculated from the PECs agreed well with both experimental and other accurate theoretical references. We also analyzed the wave functions using the inverse overlap weights proposed by Gallup et al. with the CFT configurations. For the X1Σ+ and A1Π states, the covalent C+(sp2) and C+(p3) configurations played important roles for bond formation. In the small internuclear distances of the C1Σ+, D1Π, and 31Σ+ states, the covalent character was also dominant as a result of the electron charge transfer from C to H+. Thus, the present FC-LSE results not only are accurate but also can provide chemical understanding according to the CFT.
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Affiliation(s)
- Hiroyuki Nakashima
- Quantum Chemistry Research Institute, Kyoto Technoscience Center 16, 14 Yoshida Kawaramachi, Sakyo-ku, Kyoto 606-8305, Japan
| | - Hiroshi Nakatsuji
- Quantum Chemistry Research Institute, Kyoto Technoscience Center 16, 14 Yoshida Kawaramachi, Sakyo-ku, Kyoto 606-8305, Japan
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Vidal-García A, Falgarone E, Battaia FA, Godard B, Ivison RJ, Zwaan MA, Herrera C, Frayer D, Andreani P, Li Q, Gavazzi R, Bergin E, Walter F, Omont A. CH +(1-0) in a z~2.8 galaxy group: Probe of multi-phasic turbulent gas reservoirs. EPJ WEB OF CONFERENCES 2022. [DOI: 10.1051/epjconf/202226500045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Starburst galaxies at redshifts z~2 to 4 are among the most intensely star-forming galaxies in the universe. The way they accrete their gas to form stars at such high rates is still a controversial issue. We have detected the CH+(1-0) line in emission and/or in absorption in all the gravitationally lensed starburst galaxies observed so far with ALMA in this redshift range. The unique spectroscopic and chemical properties of CH+ allow its rotational transition to highlight the sites of dissipation of mechanical energy. Whilst the absorption lines reveal highly turbulent reservoirs of low-density molecular gas extending far out of the galaxies, the broad emission lines with widths up to a few thousands of km/s, arise in myriad molecular shocks powered by the feedback of star formation and possibly active galactic nuclei. The CH+(1-0) lines therefore probe the sites of prodigious energy releases, mainly stored in turbulent reservoirs before being radiated away. These turbulent reservoirs act as extended buffers of mass and energy over timescales of a few tens to hundreds of Myr. Their mass supply involves multi-phasic gas inflows from galaxy mergers and/or cold stream accretion, as supported by Keck/KCWI Lyα observations of one of these starburst galaxies.
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Hodge JA, da Cunha E. High-redshift star formation in the Atacama large millimetre/submillimetre array era. ROYAL SOCIETY OPEN SCIENCE 2020; 7:200556. [PMID: 33489252 PMCID: PMC7813222 DOI: 10.1098/rsos.200556] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 11/02/2020] [Indexed: 06/12/2023]
Abstract
The Atacama Large Millimetre/submillimetre Array (ALMA) is currently in the process of transforming our view of star-forming galaxies in the distant ( z ≳ 1 ) universe. Before ALMA, most of what we knew about dust-obscured star formation in distant galaxies was limited to the brightest submillimetre sources-the so-called submillimetre galaxies (SMGs)-and even the information on those sources was sparse, with resolved (i.e. sub-galactic) observations of the obscured star formation and gas reservoirs typically restricted to the most extreme and/or strongly lensed sources. Starting with the beginning of early science operations in 2011, the last 9 years of ALMA observations have ushered in a new era for studies of high-redshift star formation. With its long baselines, ALMA has allowed observations of distant dust-obscured star formation with angular resolutions comparable to-or even far surpassing-the best current optical telescopes. With its bandwidth and frequency coverage, it has provided an unprecedented look at the associated molecular and atomic gas in these distant galaxies through targeted follow-up and serendipitous detections/blind line scans. Finally, with its leap in sensitivity compared to previous (sub-)millimetre arrays, it has enabled the detection of these powerful dust/gas tracers much further down the luminosity function through both statistical studies of colour/mass-selected galaxy populations and dedicated deep fields. We review the main advances ALMA has helped bring about in our understanding of the dust and gas properties of high-redshift ( z ≳ 1 ) star-forming galaxies during these first 9 years of its science operations, and we highlight the interesting questions that may be answered by ALMA in the years to come.
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Affiliation(s)
- J. A. Hodge
- Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
| | - E. da Cunha
- International Centre for Radio Astronomy Research, University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009, Australia
- Research School of Astronomy and Astrophysics, Australian National University, Canberra, Australian Capital Territory 2611, Australia
- ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D)
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A 100-kiloparsec wind feeding the circumgalactic medium of a massive compact galaxy. Nature 2019; 574:643-646. [PMID: 31666723 DOI: 10.1038/s41586-019-1686-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2019] [Accepted: 08/16/2019] [Indexed: 11/08/2022]
Abstract
Ninety per cent of baryons are located outside galaxies, either in the circumgalactic or intergalactic medium1,2. Theory points to galactic winds as the primary source of the enriched and massive circumgalactic medium3-6. Winds from compact starbursts have been observed to flow to distances somewhat greater than ten kiloparsecs7-10, but the circumgalactic medium typically extends beyond a hundred kiloparsecs3,4. Here we report optical integral field observations of the massive but compact galaxy SDSS J211824.06+001729.4. The oxygen [O II] lines at wavelengths of 3726 and 3729 angstroms reveal an ionized outflow spanning 80 by 100 square kiloparsecs, depositing metal-enriched gas at 10,000 kelvin through an hourglass-shaped nebula that resembles an evacuated and limb-brightened bipolar bubble. We also observe neutral gas phases at temperatures of less than 10,000 kelvin reaching distances of 20 kiloparsecs and velocities of around 1,500 kilometres per second. This multi-phase outflow is probably driven by bursts of star formation, consistent with theory11,12.
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Goicoechea JR, Santa-Maria MG, Bron E, Teyssier D, Marcelino N, Cernicharo J, Cuadrado S. Molecular tracers of radiative feedback in Orion (OMC-1) Widespread CH + ( J = 1-0), CO (10-9), HCN (6-5), and HCO + (6-5) emission. ASTRONOMY AND ASTROPHYSICS 2019; 622:A91. [PMID: 30820064 PMCID: PMC6390943 DOI: 10.1051/0004-6361/201834409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Young massive stars regulate the physical conditions, ionization, and fate of their natal molecular cloud and surroundings. It is important to find tracers that help quantifying the stellar feedback processes that take place at different spatial scales. We present ~85 arcmin2 (~1.3 pc2) velocity-resolved maps of several submillimeter molecular lines, taken with Herschel/HIFI, toward the closest high-mass star-forming region, the Orion molecular cloud 1 core (OMC-1). The observed rotational lines include probes of warm and dense molecular gas that are difficult, if not impossible, to detect from ground-based telescopes: CH+ (J = 1-0), CO (J = 10-9), HCO+ (J = 6-5) and HCN (J = 6-5), and CH (N, J =1, 3/2-1, 1/2). These lines trace an extended but thin layer (A V ≃3-6 mag or ~1016 cm) of molecular gas at high thermal pressure, P th = n H · T k ≈ 107 - 109 cm-3 K, associated with the far ultraviolet (FUV) irradiated surface of OMC-1. The intense FUV radiation field, emerging from massive stars in the Trapezium cluster, heats, compresses and photoevaporates the cloud edge. It also triggers the formation of specific reactive molecules such as CH+. We find that the CH+ (J = 1-0) emission spatially correlates with the flux of FUV photons impinging the cloud: G 0 from ~103 to ~105. This correlation is supported by constant-pressure photodissociation region (PDR) models in the parameter space P th/G 0 ≈ [5 · 103 - 8 · 104] cm-3 K where many observed PDRs seem to lie. The CH+ (J = 1-0) emission spatially correlates with the extended infrared emission from vibrationally excited H2 (v ≥ 1), and with that of [C ii] 158 μm and CO J = 10-9, all emerging from FUV-irradiated gas. These correlations link the presence of CH+ to the availability of C+ ions and of FUV-pumped H2 (v ≥ 1) molecules. We conclude that the parsec-scale CH+ emission and narrow-line (Δv ≃ 3 km s-1) mid-J CO emission arises from extended PDR gas and not from fast shocks. PDR line tracers are the smoking gun of the stellar feedback from young massive stars. The PDR cloud surface component in OMC-1, with a mass density of 120-240 M ⊙ pc-2, represents ~5% to ~10% of the total gas mass, however, it dominates the emitted line luminosity; the average CO J = 10-9 surface luminosity in the mapped region being ~35 times brighter than that of CO J = 2-1. These results provide insights into the source of submillimeter CH+ and mid-J CO emission from distant star-forming galaxies.
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Affiliation(s)
- Javier R Goicoechea
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - Miriam G Santa-Maria
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - Emeric Bron
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - David Teyssier
- Telespazio Vega UK Ltd for ESA/ESAC. Urbanización Villafranca del Castillo, Villanueva de la Cañada, E-28692 Madrid, Spain
| | - Nuria Marcelino
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - José Cernicharo
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
| | - Sara Cuadrado
- Instituto de Física Fundamental (CSIC). Calle Serrano 121, E-28006, Madrid, Spain
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Abstract
Galaxy-scale outflows of gas, or galactic winds (GWs), driven by energy from star formation are a pivotal mechanism for regulation of star formation in the current model of galaxy evolution. Observations of this phenomenon have proliferated through the wide application of old techniques on large samples of galaxies, the development of new methods, and advances in telescopes and instrumentation. I review the diverse portfolio of direct observations of stellar GWs since 2010. Maturing measurements of the ionized and neutral gas properties of nearby winds have been joined by exciting new probes of molecular gas and dust. Low-z techniques have been newly applied in large numbers at high z. The explosion of optical and near-infrared 3D imaging spectroscopy has revealed the complex, multiphase structure of nearby GWs. These observations point to stellar GWs being a common feature of rapidly star-forming galaxies throughout at least the second half of cosmic history, and suggest that scaling relationships between outflow and galaxy properties persist over this period. The simple model of a modest-velocity, biconical flow of multiphase gas and dust perpendicular to galaxy disks continues to be a robust descriptor of these flows.
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Zhang ZY, Romano D, Ivison RJ, Papadopoulos PP, Matteucci F. Stellar populations dominated by massive stars in dusty starburst galaxies across cosmic time. Nature 2018; 558:260-263. [PMID: 29867162 DOI: 10.1038/s41586-018-0196-x] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Accepted: 02/27/2018] [Indexed: 11/09/2022]
Abstract
All measurements of cosmic star formation must assume an initial distribution of stellar masses-the stellar initial mass function-in order to extrapolate from the star-formation rate measured for typically rare, massive stars (of more than eight solar masses) to the total star-formation rate across the full stellar mass spectrum 1 . The shape of the stellar initial mass function in various galaxy populations underpins our understanding of the formation and evolution of galaxies across cosmic time 2 . Classical determinations of the stellar initial mass function in local galaxies are traditionally made at ultraviolet, optical and near-infrared wavelengths, which cannot be probed in dust-obscured galaxies2,3, especially distant starbursts, whose apparent star-formation rates are hundreds to thousands of times higher than in the Milky Way, selected at submillimetre (rest-frame far-infrared) wavelengths4,5. The 13C/18O isotope abundance ratio in the cold molecular gas-which can be probed via the rotational transitions of the 13CO and C18O isotopologues-is a very sensitive index of the stellar initial mass function, with its determination immune to the pernicious effects of dust. Here we report observations of 13CO and C18O emission for a sample of four dust-enshrouded starbursts at redshifts of approximately two to three, and find unambiguous evidence for a top-heavy stellar initial mass function in all of them. A low 13CO/C18O ratio for all our targets-alongside a well tested, detailed chemical evolution model benchmarked on the Milky Way 6 -implies that there are considerably more massive stars in starburst events than in ordinary star-forming spiral galaxies. This can bring these extraordinary starbursts closer to the 'main sequence' of star-forming galaxies 7 , although such main-sequence galaxies may not be immune to changes in initial stellar mass function, depending on their star-formation densities.
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Affiliation(s)
- Zhi-Yu Zhang
- Institute for Astronomy, University of Edinburgh, Edinburgh, UK.,European Southern Observatory, Garching, Germany
| | - D Romano
- INAF, Astrophysics and Space Science Observatory, Bologna, Italy
| | - R J Ivison
- Institute for Astronomy, University of Edinburgh, Edinburgh, UK. .,European Southern Observatory, Garching, Germany.
| | - Padelis P Papadopoulos
- Institute for Astronomy, University of Edinburgh, Edinburgh, UK.,Department of Physics, Section of Astrophysics, Astronomy and Mechanics, Aristotle University of Thessaloniki, Thessaloniki, Greece.,Research Center for Astronomy, Academy of Athens, Athens, Greece
| | - F Matteucci
- Department of Physics, Section of Astronomy, University of Trieste, Trieste, Italy.,INAF, Osservatorio Astronomico di Trieste, Trieste, Italy.,INFN, Sezione di Trieste, Trieste, Italy
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Doménech JL, Jusko P, Schlemmer S, Asvany O. First Laboratory Detection of Vibration-Rotation Transitions of 12CH + and 13CH + and Improved Measurement of their Rotational Transition Frequencies. THE ASTROPHYSICAL JOURNAL 2018; 857:61. [PMID: 29861500 PMCID: PMC5975947 DOI: 10.3847/1538-4357/aab36a] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The long-searched C-H stretches of the fundamental ions CH+ and 13CH+ have been observed for the first time in the laboratory. For this, the state-dependent attachment of He atoms to these ions at cryogenic temperatures has been exploited to obtain high-resolution rovibrational data. In addition, the lowest rotational transitions of CH+, 13CH+ and CD+ have been revisited and their rest frequency values improved substantially.
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Affiliation(s)
- José L. Doménech
- Instituto de Estructura de la Materia (IEM-CSIC), Serrano 123, E28006 Madrid, Spain
| | - Pavol Jusko
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - Stephan Schlemmer
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
| | - Oskar Asvany
- I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
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