<scp>3d-pdr</scp>: a new three-dimensional astrochemistry code for treating photodissociation regions

Bisbas, Thomas G.; Bell, T. A.; Viti, S.; Yates, J.; Barlow, M. J.

doi:10.1111/j.1365-2966.2012.22077.x

Cited by 112 publications

(154 citation statements)

References 78 publications

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“…We recently coupled torus with the 3d-pdr code of Bisbas et al (2012), the details and testing of which are given thoroughly in Bisbas et al (2015). This approach is novel since the UV field used in the PDR calculation is determined explicitly by the Monte Carlo radiation transport (typically the Draine field is a free parameter for PDR codes).…”

Section: Torus-3dpdrmentioning

confidence: 99%

On the relative importance of different microphysics on the D-type expansion of galactic H ii regions

Haworth

Harries

Acreman

et al. 2015

Mon. Not. R. Astron. Soc.

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Radiation hydrodynamics (RHD) simulations are used to study many astrophysical phenomena, however they require the use of simplified radiation transport and thermal prescriptions to reduce computational cost. In this paper we present a systematic study of the importance of microphysical processes in RHD simulations using the example of D-type H ii region expansion. We compare the simplest hydrogen-only models with those that include: ionisation of H, He, C, N, O, S and Ne, different gas metallicity, non-LTE metal line blanketed stellar spectral models of varying metallicity, radiation pressure, dust and treatment of photodissociation regions. Each of these processes are explicitly treated using modern numerical methods rather than parameterisation. In line with expectations, changes due to microphysics in either the effective number of ionising photons or the thermal structure of the gas lead to differences in D-type expansion. In general we find that more realistic calculations lead to the onset of Dtype expansion at smaller radii and a slower subsequent expansion. Simulations of star forming regions using simplified microphysics are therefore likely overestimating the strength of radiative feedback. We find that both variations in gas metallicity and the inclusion of dust can affect the ionisation front evolution at the 10-20 per cent level over 500 kyr, which could substantially modify the results of simplified 3D models including feedback. Stellar metallicity, radiation pressure and the inclusion of photodissociation regions are all less significant effects at the 1 per cent level or less, rendering them of minor importance in the modelling the dynamical evolution of H ii regions.

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Section: Torus-3dpdrmentioning

confidence: 99%

On the relative importance of different microphysics on the D-type expansion of galactic H ii regions

Haworth

Harries

Acreman

et al. 2015

Mon. Not. R. Astron. Soc.

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“…We model our line intensities and line ratios using the 3d-pdr code (Bisbas et al 2012) which has been fully benchmarked against the tests discussed in Röllig et al (2007). We use 3d-pdr to generate a grid of different uniformdensity, one-dimensional simulations in which we vary the density (specifically the H-nucleus number density, nH) and the UV radiation field (G).…”

Section: Model Descriptionmentioning

confidence: 99%

“…The parameter space covers 2 log(nH/cm −3 ) 7 in density and −0.2 log(G/G•) 5.8 in UV field, where G• corresponds to the radiation field strength in Habing units. In general we adopt the heating and cooling functions as described in Bisbas et al (2012) with the following updates. We use the Bakes & Tielens (1994) PAH photoelectric heating with the modifications suggested by Wolfire et al (2003) to account for the revised PAH abundance estimate from Spitzer data.…”

Section: Model Descriptionmentioning

confidence: 99%

ALMA observations of atomic carbon inz ∼ 4 dusty star-forming galaxies

Bothwell

Aguirre

Aravena

et al. 2016

Mon. Not. R. Astron. Soc.

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We present ALMA [Ci](1−0) (rest frequency 492 GHz) observations for a sample of 13 strongly-lensed dusty star-forming galaxies originally discovered at 1.4mm in a blankfield survey by the South Pole Telescope. We compare these new data with available [Ci] observations from the literature, allowing a study of the ISM properties of ∼ 30 extreme dusty star-forming galaxies spanning a redshift range 2 < z < 5. Using the [Ci] line as a tracer of the molecular ISM, we find a mean molecular gas mass for SPTDSFGs of 6.6 × 10 10 M . This is in tension with gas masses derived via low-J 12 CO and dust masses; bringing the estimates into accordance requires either (a) an elevated CO-to-H 2 conversion factor for our sample of α CO ∼ 2.5 and a gas-to-dust ratio ∼ 200, or (b) an high carbon abundance X CI ∼ 7 × 10 −5 . Using observations of a range of additional atomic and molecular lines (including [Ci], [Cii], and multiple transitions of CO), we use a modern Photodissociation Region code (3d-pdr) to assess the physical conditions (including the density, UV radiation field strength, and gas temperature) within the ISM of the DSFGs in our sample. We find that the ISM within our DSFGs is characterised by dense gas permeated by strong UV fields. We note that previous efforts to characterise PDR regions in DSFGs may have significantly under-estimated the density of the ISM. Combined, our analysis suggests that the ISM of extreme dusty starbursts at high redshift consists of dense, carbon-rich gas not directly comparable to the ISM of starbursts in the local Universe.

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“…torus-3dpdr currently considers a reduced network that comprises 33 species and 330 reactions, tailored such that it provides temperatures to with ∼ 10 per cent of the 3d-pdr (Bisbas et al 2012) full chemical network (215 species, over 3000 reactions). It iteratively solves for the composition and temperature structure until convergence, using the approach detailed by Bisbas et al (2012Bisbas et al ( , 2015.…”

Section: Photochemical-dynamics With Torus-3dpdrmentioning

confidence: 99%

Where can a Trappist-1 planetary system be produced?

Haworth

Facchini

Clarke

et al. 2018

Monthly Notices of the Royal Astronomical Society

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We study the evolution of protoplanetary discs that would have been precursors of a Trappist-1 like system under the action of accretion and external photoevaporation in different radiation environments. Dust grains swiftly grow above the critical size below which they are entrained in the photoevaporative wind, so although gas is continually depleted, dust is resilient to photoevaporation after only a short time. This means that the ratio of the mass in solids (dust plus planetary) to the mass in gas rises steadily over time. Dust is still stripped early on, and the initial disc mass required to produce the observed 4 M ⊕ of Trappist-1 planets is high. For example, assuming a Fatuzzo & Adams (2008) distribution of UV fields, typical initial disc masses have to be > 30 per cent the stellar (which are still Toomre Q stable) for the majority of similar mass M dwarfs to be viable hosts of the Trappist-1 planets. Even in the case of the lowest UV environments observed, there is a strong loss of dust due to photoevaporation at early times from the weakly bound outer regions of the disc. This minimum level of dust loss is a factor two higher than that which would be lost by accretion onto the star during 10 Myr of evolution. Consequently even in these least irradiated environments, discs that are viable Trappist-1 precursors need to be initially massive (> 10 per cent of the stellar mass).

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3d-pdr: a new three-dimensional astrochemistry code for treating photodissociation regions

Cited by 112 publications

References 78 publications

On the relative importance of different microphysics on the D-type expansion of galactic H ii regions

On the relative importance of different microphysics on the D-type expansion of galactic H ii regions

ALMA observations of atomic carbon inz ∼ 4 dusty star-forming galaxies

Where can a Trappist-1 planetary system be produced?

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