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a02b60ca7caeed89a8e59580d1b2926052aa287d
subsection
264
279
The group
Math., volume=20, number=8, pages=1850014, 43, url=https://doi.org/10.1142/S0219199718500141, review=3883405,Kobayashibook author=Kobayashi, Shoshichi, title=Differential geometry of complex vector bundles, series=Publications of the Mathematical Society of Japan, publisher=Princeton University Press, Princeton, NJ; Pr...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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708257d80117e81a6821444fa162be5f48276122
subsection
265
279
The group
Topol., volume=13, number=4, pages=18771944, url=http://dx.doi.org.umiss.idm.oclc.org/10.2140/gt.2009.13.1877, review=2497314,McLeanMBSequencemisc author=McLean, Mark, title=Computing symplectic homology of affine varieties (using spectral sequences), date=2016, url=http://www.math.stonybrook.edu/ markmclean/talks/spec...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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357be215d95325b3dd802681d0a8c2985722008a
subsection
266
279
The group
Symplectic Geom., volume=11, number=1, pages=109133, url=http://projecteuclid.org.umiss.idm.oclc.org/euclid.jsg/1362146735, review=3022923,Pascaleffunpublished author=Pascaleff, James, title=On the symplectic cohomology of log Calabi–Yau surfaces, date=2013, note=arXiv:1304.5298,Ritterarticle author=Ritter, Alexander F...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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278a25c8838fab28f0691afef0bd97e4db0836ab
subsection
267
279
The group
Ann., volume=368, number=1-2, pages=367390, url=https://doi.org/10.1007/s00208-016-1478-y, review=3651577,SiebertGWarticle author=Siebert, Bernd, title=Algebraic and symplectic Gromov–Witten invariants coincide, date=1999, ISSN=0373-0956, journal=Ann. Inst. Fourier (Grenoble), volume=49, number=6, pages=17431795, url=h...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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bc0a4593112d1de009142c5f86b03159fd09fee4
subsection
268
279
The group
Given k\ge 2,\partial {m}_{k+1} &= 2 \, n_L(M,m) \, \widehat{M}_{k-1} \,+ \,\big ( n_{L_1} \, + \, n_{L_2} \big )\, \widehat{m}_k = \\ &= 2 \times 1 \, \widehat{M}_{k-1} \, + \, \big (1 + 1 \big )\, \widehat{m}_k = 2 \, \widehat{M}_{k-1} + 2 \, \widehat{m}_kand\partial {M}_{k} &= \big ( n_{L_1} \, + \, n_{L_2} \big )\,...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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65c5dd6fd29218cff0d56af08a98bfb505c8a507
subsection
269
279
The group
We can conclude the following.Proposition 11.1SH_*(T^*S^2 ; \mathbb {Z}) = \mathbb {Z}\left\langle c, {m}_{1}, e, {M}_{k} - {m}_{k+1}, \widehat{M}_{k} \right\rangle \oplus \mathbb {Z}/ 2 \left\langle e + \widehat{m}_{1}, \widehat{M}_{k} + \widehat{m}_{k+1} \right\ranglewhere we take all k \ge 1.We can compare these res...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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5685ef16ddf2e7e75ec2e5a16afb72a6a3e985b0
subsection
270
279
The group
Phys., volume=24, publisher=Eur. Math. Soc., Zürich, pages=271485, review=3444367,AlbersFrauenfelderNegativeLineBundlesarticle author=Albers, Peter, author=Frauenfelder, Urs, title=Floer homology for negative line bundles and Reeb chords in prequantization spaces, date=2009, ISSN=1930-5311, journal=J. Mod. Dyn., volume...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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cdedb36f5f8b35c6562ee9f630632bbff2cb7caa
subsection
271
279
The group
Topol., volume=7, pages=799888, url=https://doi.org/10.2140/gt.2003.7.799, review=2026549,BiranBarriersarticle author=Biran, Paul, title=Lagrangian barriers and symplectic embeddings, date=2001, ISSN=1016-443X, journal=Geom. Funct. Anal., volume=11, number=3, pages=407464, url=http://dx.doi.org/10.1007/PL00001678, revi...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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7b90b052629b9c2791a31712dc22e2deea4e590b
subsection
272
279
The group
S., author=Yan, Jun, title=The loop homology algebra of spheres and projective spaces, date=2004, booktitle=Categorical decomposition techniques in algebraic topology (Isle of Skye, 2001), series=Progr. Math., volume=215, publisher=Birkhäuser, Basel, pages=7792, review=2039760,DiogoLisiSplitunpublished author=Diogo, Lu...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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71717dda6eb88ed4e076eb49594aea3877e25581
subsection
273
279
The group
Math., volume=41, number=6, pages=775813, url=http://dx.doi.org.umiss.idm.oclc.org/10.1002/cpa.3160410603, review=948771,GanatraThesisbook author=Ganatra, Sheel, title=Symplectic Cohomology and Duality for the Wrapped Fukaya Category, publisher=ProQuest LLC, Ann Arbor, MI, date=2012, url=http://gateway.proquest.com.umi...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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98f1fd538b77fbf115155bf485311eb02327fb4d
subsection
274
279
The group
Math., volume=82, number=2, pages=307347, url=https://doi.org/10.1007/BF01388806, review=809718,HuRuanarticle author=Hu, JianXun, author=Ruan, YongBin, title=Positive divisors in symplectic geometry, date=2013, ISSN=1674-7283, journal=Sci. China Math., volume=56, number=6, pages=11291144, url=http://dx.doi.org/10.1007/...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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bd1065e4e187875ebf5f7806a93aa59b2480f7a1
subsection
275
279
The group
Math., volume=20, number=8, pages=1850014, 43, url=https://doi.org/10.1142/S0219199718500141, review=3883405,Kobayashibook author=Kobayashi, Shoshichi, title=Differential geometry of complex vector bundles, series=Publications of the Mathematical Society of Japan, publisher=Princeton University Press, Princeton, NJ; Pr...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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02c62be8edf4688805564220f6f56cafb5a76338
subsection
276
279
The group
Topol., volume=13, number=4, pages=18771944, url=http://dx.doi.org.umiss.idm.oclc.org/10.2140/gt.2009.13.1877, review=2497314,McLeanMBSequencemisc author=McLean, Mark, title=Computing symplectic homology of affine varieties (using spectral sequences), date=2016, url=http://www.math.stonybrook.edu/ markmclean/talks/spec...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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70df35567d88f2267e47cecdff165ed3b08ae413
subsection
277
279
The group
Symplectic Geom., volume=11, number=1, pages=109133, url=http://projecteuclid.org.umiss.idm.oclc.org/euclid.jsg/1362146735, review=3022923,Pascaleffunpublished author=Pascaleff, James, title=On the symplectic cohomology of log Calabi–Yau surfaces, date=2013, note=arXiv:1304.5298,Ritterarticle author=Ritter, Alexander F...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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6b8b5d0076acc770c23b9e6fb71606d3ae66e8dc
subsection
278
279
The group
Ann., volume=368, number=1-2, pages=367390, url=https://doi.org/10.1007/s00208-016-1478-y, review=3651577,SiebertGWarticle author=Siebert, Bernd, title=Algebraic and symplectic Gromov–Witten invariants coincide, date=1999, ISSN=0373-0956, journal=Ann. Inst. Fourier (Grenoble), volume=49, number=6, pages=17431795, url=h...
{ "cite_spans": [] }
10.1112/topo.12105
1804.08014
Symplectic Homology of complements of smooth divisors
[ "Luís Diogo", "Samuel T. Lisi" ]
[ "math.SG" ]
2,018
en
Mathematics
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7844f721afef1f039ce3d1605a5cf82a43fc6895
abstract
0
47
Abstract
We present Lampray: a multi-group long characteristics ray tracing method for adaptive mesh radiation hydrodynamics in the Ramses code. It avoids diffusion, captures shadows, and treats colliding beams correctly, and therefore complements existing moment-based ray tracing in Ramses. Lampray includes different options f...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
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c88276a93fd0568d5f039fc12017aba8685d82d7
subsection
1
47
Introduction
The interaction between radiation and matter is important for a majority of objects in the Universe, and often required for accurate, quantitative numerical modelling in astrophysics. In the interstellar medium (ISM) the role of radiative stellar feedback versus feedback from supernovae and galactic dynamics is debated...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
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83544a01be67bea13f17503b47889a7e9f0bfd27
subsection
2
47
Introduction
Both flux-limited diffusion , , and the M1 method , have been implemented on adaptive mesh for use in radiation-hydrodynamics. rayramses is a ray-tracing tool for post-processing of cosmological simulations using curved rays to capture gravitational lensing, while provide an algorithm to estimate column densities takin...
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1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
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subsection
3
47
Numerical methods
Radiation hydrodynamics model the interaction and evolution of radiation and matter with a fluid description. Radiation can transport energy and momentum through emission, absorption, and scattering. In addition, when high-energy photons are present radiation has important consequences for the chemical composition of t...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
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32d92ede080effb9b0f6b509448aaec8cea0f3f0
subsection
4
47
Numerical methods
The molecular weight of the gas is \mu = 1 / (\sum X_s / m_s).lampray does not compute the radiative pressure and momentum, and we have for clarity left out other contributions from e.g. magnetic fields, self-gravity, and external forces, which are included in ramses.The dynamical time-scale of the fluid is dictated by...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
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955f04ba5c434787618b2a00fb2a5a112c47b24e
subsection
5
47
Numerical methods
The mean intensity, which is the main input to compute the effect of radiation on matter, isJ_{\nu }\left({x}\right)=\frac{1}{4\pi }\int _{0}^{4\pi }I_{\nu }\left({x},\Omega \right)\mathrm {d}\Omega \,,while the intensity of the emitted radiation is given by the source functionS_{\nu }\left({x}\right)=\frac{j_{*,\nu }\...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.0161735936999321, 0.031248603016138077, -0.033934030681848526, -0.0013465279480442405, -0.014724073000252247, -0.047910455614328384, 0.02056792750954628, 0.02873101457953453, 0.03034837543964386, 0.0377790741622448, -0.051267240196466446, -0.03454435244202614, -0.041898760944604874, 0.0...
ca7c2d7625b4355c3b850628a346e31a72033527
subsection
6
47
Numerical methods
In particular, for a photo-ionization or photo-dissociation reactionk_{j} = 4\pi \int ^\infty _{\nu _{\mathrm {th}}} \frac{\sigma _{\mathrm {j},\nu } J_\nu }{h\nu } \mathrm {d}\nu ,where \sigma _{j,\nu } is the frequency dependent photo cross section for reaction j and \nu _{\mathrm {th}} is the energy threshold of the...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ 0.0038092159666121006, 0.0021783297415822744, -0.041201334446668625, 0.0005059561808593571, -0.021729888394474983, -0.07758058607578278, -0.02842891961336136, -0.027101321145892143, -0.0124595882371068, 0.03875977173447609, -0.022126642987132072, -0.00804951973259449, -0.06421304494142532, ...
ccdfa6749df8dc208dd45d1aba3e43f5f18bb2f7
subsection
7
47
Radiative transfer
The radiative transfer equation is solved explicitly using long characteristics ray tracing. We discretise the intensity in frequency into a set of bins so I_{\textrm {bin}} = \int ^{\nu _{u\left(\textrm {bin}\right)}} _{\nu _{l\left(\textrm {bin}\right)}} I_\nu \textrm {d}\nu , where \nu _{u\left(\textrm {bin}\right)}...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.024303970858454704, 0.009993158280849457, -0.025783874094486237, 0.0022618102375417948, -0.0029502701945602894, 0.014257414266467094, 0.011534088291227818, 0.0055992198176681995, 0.022000204771757126, 0.029674340039491653, -0.04018622636795044, -0.00016424823843408376, 0.00495080882683396...
0cb52685c68033efdbc5a4a3bd7cb19e58666679
subsection
8
47
Radiative transfer
Finally, the chemical network is evolved in each cell ignoring any PdV work using the new radiation field in each cell, giving a net heating / cooling term by which the total energy is changed. A new mean molecular weight and adiabatic index is also computed after the chemistry update. The timestep can be adaptively su...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.0016176017234101892, -0.0014125402085483074, -0.03332870081067085, 0.004272910300642252, -0.030093496665358543, -0.030062975361943245, 0.00886628869920969, 0.014596566557884216, 0.01394800003618002, 0.020921999588608742, 0.012017560191452503, 0.018571898341178894, -0.022921111434698105, ...
43dc06bee64b098a46fe1fcc67aa4e5beee8372f
subsection
9
47
Coupling to chemistry
We have implemented two methods that solve Eqn.(REF ), Eqn.(REF ) and Eqn.(REF ). The first method (Sect. REF ) solves it for any set of photo-reactions and in connection with an arbitrary chemical network using the krome package. It however requires a fairly restrictive time step if a correct propagation speed of fast...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.02032785303890705, -0.0038019344210624695, -0.02533351071178913, -0.027012238278985023, -0.002344494452700019, -0.0016119590727612376, 0.007787002716213465, 0.015322196297347546, 0.01196474302560091, -0.00041205110028386116, -0.016634654253721237, 0.015993686392903328, -0.0240210518240928...
a770fa4db702bf2f806d3b532dd169fe74d9989c
subsection
10
47
Photo-chemistry with KROME
krome is a framework that generates code from a description of a chemical network to efficiently solve its time-dependent evolution. It is able to compute photo-chemical rate coefficients based on frequency-binned mean intensities and on frequency-dependent photo cross-sections where available, and include the latter t...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1101, "openalex_id": "", "raw": "Abel T., Norman M. L., Madau P., 1999, , 523, 66", "source_ref_id": "7d73b8beab11b759cea3fbf61100f7b4108a5102", "start": 977 }, { "arxiv_id": "", "doi": "", "e...
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ 0.010162157006561756, -0.009765436872839928, -0.04122845083475113, -0.02358963154256344, -0.007873383350670338, -0.06878529489040375, 0.01065042894333601, 0.004108349792659283, -0.004596621263772249, 0.040801212191581726, -0.04421911761164665, -0.0030688645783811808, -0.02639719471335411, ...
05193fe5d66544cb482a2e717826d3cb9ffc3dfc
subsection
11
47
Photo-chemistry with KROME
In this case, the optical depth element is\Delta \tau _{\nu }=\sum _{\mathrm {r}\in \mathcal {P}}\sigma _{\nu ,\mathrm {r}}n_{s(\mathrm {r})}\Delta l\,,where the sum is over all photo-reactions \mathcal {P}: s(\mathrm {r}) + \gamma \rightarrow p(\mathrm {r}). s(\mathrm {r}) is the reactant and p(r) is the product in re...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.009978605434298515, -0.01771431416273117, -0.036313582211732864, -0.01486110407859087, 0.004550640936940908, -0.004348475020378828, 0.04479692131280899, 0.0131293423473835, 0.029233958572149277, 0.034391097724437714, -0.031171699985861778, 0.007449624128639698, -0.002948571229353547, 0....
ca7d120b5980ecf8c37f111ed867a4ba618495c3
subsection
12
47
Photo-chemistry with KROME
In our example calculation of the structure of a photo-ionized region irradiated with the spectrum from (Sect. REF ), we find that the most accurate method is to use the unweighted average, combined with careful placement of bin limits. To describe the ionization transitions of H and He as accurately as possible with f...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.01982700824737549, -0.009447973221540451, -0.043469835072755814, 0.023887041956186295, 0.028420235961675644, -0.010127189569175243, 0.01997964084148407, -0.010936143808066845, 0.012233522720634937, 0.04063086584210396, -0.05055199936032295, 0.000517997716087848, 0.008539807982742786, 0....
80efa1e1a71616ce08755cf182beae7c2be1a1b1
subsection
13
47
Photo-chemistry with KROME
The optical depth can be expressed in terms of the dust column density, as well as the visual extinction as\tau _{\mathrm {bin}} = \kappa _{\mathrm {bin,d}}f_{\mathrm {d}}\frac{N_{\mathrm {H}}\,m_\mathrm {p}}{ x_{\mathrm {H}}} = \gamma _\mathrm {bin}A_\mathrm {v}\, .Here, f_{\mathrm {d}} is the dust mass fraction, N_{\...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.04919056594371796, -0.04290442541241646, 0.02273385226726532, -0.01405226718634367, 0.004287390969693661, -0.029630297794938087, -0.0006632296717725694, 0.007964476943016052, 0.04830562323331833, 0.05782637745141983, -0.03323109447956085, -0.029554009437561035, 0.01171022281050682, 0.02...
2918e0736a4e040de84efa1715b2e05eecccc527
subsection
14
47
Hydrogen ionization with
In an explicit method, the evolution of radiatively driven ionization fronts can require a very small time step and cell size to resolve correctly the ionization front, and obtain the right propagation speed. c2ray is an explicitly photon-conserving and causally implicit photo-ionization method that takes the ionizatio...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.01626947708427906, -0.004044475965201855, -0.03553033992648125, 0.029562829062342644, -0.026571443304419518, -0.03986479714512825, -0.018314607441425323, 0.03650711849331856, 0.019840825349092484, 0.01713941991329193, -0.00950070284307003, 0.0020088835153728724, -0.0021119031589478254, ...
a6e2767c07db11f9452670d29001dbd8e9345786
subsection
15
47
Interstellar radiation field as diffuse emission
In earlier 3D dynamical models of PDRs, the external radiation field has been simulated as an ISRF, attenuated through a column density measured from the edge of the simulation box , . While this works well when modelling an isolated cloud that stays more or less centred in the simulated box, when simulating turbulent ...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.05360153317451477, -0.01336985919624567, -0.02573239989578724, -0.032631002366542816, -0.01680389791727066, -0.031532108783721924, 0.00825695600360632, 0.0026289476081728935, 0.02295464277267456, 0.04856494441628456, -0.04157476872205734, 0.01558290608227253, -0.02562556229531765, 0.036...
03f2d27e08c1a4f7e88ae03822c08f94bb468967
subsection
16
47
Self-shielding of H2 and CO
The self-shielding of \textrm {H}_2 and CO needs to be treated carefully to get qualitatively correct results for the two most abundant molecules in the ISM. Since this requires that one follows in detail their excited states and the associated frequencies , this is not currently achievable in 3D radiation hydrodynamic...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.04703659564256668, 0.026082266122102737, -0.048013344407081604, -0.00594825204461813, 0.0018895906396210194, -0.04517466574907303, 0.005673541221767664, -0.026738518849015236, 0.005085965618491173, 0.049142710864543915, -0.025517582893371582, -0.01945868320763111, 0.0012772144982591271, ...
875ddc3916158616289c33f44e0eafa1b5864efc
subsection
17
47
Self-shielding of H2 and CO
23, slightly relabelled here)I_{\mathrm {bin}}\left(n\right)=\sum _{i=0}^{n-1}\Delta l_{i}j_{*,\mathrm {bin},i} \mathcal {S}_{\mathrm {bin}}\left(\sum _{j=i}^{n}\mathbf {n}_{spec,j}\Delta l_{j}\right)\,,where I_{\mathrm {bin}}\left(n\right) is the intensity in the frequency range “bin” in cell n, \Delta l_{i} is the pa...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.029260937124490738, 0.0014969913754612207, -0.041892874985933304, -0.016171321272850037, 0.005934569519013166, 0.0042487857863307, -0.004729348700493574, 0.0062358747236430645, -0.011701323091983795, 0.05739293247461319, -0.051565155386924744, 0.01740705408155918, 0.000012395469639159273,...
6c46f3d4573abfeb10d051458ff3b7aa4b868bc5
subsection
18
47
Thermal balance of dust grains
Grain surface chemistry depends on the temperature of the dust grains, and is used in our chemical network for calculating the {H2} formation rate, and the freeze-out and evaporation of {H2O} and {CO} ices. The kinetic cooling or heating of the gas also depends on the temperature differential between dust and gas. In w...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.005337625741958618, 0.010186891071498394, -0.03241491690278053, -0.019702285528182983, -0.020419565960764885, -0.04083913192152977, -0.016131151467561722, -0.005169751588255167, 0.00012280544615350664, 0.04657736420631409, -0.0358944833278656, 0.012216638773679733, -0.001540433382615447, ...
713235558295efce415b4bd7176b1f9151eb1b2c
subsection
19
47
Thermal balance of dust grains
Then the radiation absorbed by the dust grains can be calculated as\Gamma _\mathrm {abs} = \sum _{i \in \mathrm {bins}} J_i \tilde{\Gamma }_\mathrm {abs,i}\,,where\tilde{\Gamma }_\mathrm {abs,i} = \int _{E_\mathrm {min, i}}^{E_\mathrm {max, i}} {\rm d}E\, \int {\rm d}a\, \pi a^2 \varphi (a) \frac{Q_\mathrm {abs}(a,E)}{...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ 0.013104136101901531, 0.03469011187553406, -0.03252388536930084, -0.012966840527951717, -0.02117408812046051, -0.04225664585828781, -0.01746709644794464, -0.03633766248822212, 0.012623600661754608, 0.04860277101397514, -0.037283480167388916, 0.017421331256628036, -0.03243235498666763, 0.00...
0cd6160913009e6a227d8c52d0e507b52367f461
subsection
20
47
Adsorption and desorption of CO and H
For the adsorption reaction rate coefficients per gas molecule for species s, k_\mathrm {ads,s}, we follow , .k_\mathrm {ads,s} = \sigma _s v_\mathrm {gas,s} n_\mathrm {dust}\,,where \sigma _s is the cross section, v_\mathrm {gas,s} is the thermal velocity of species s, and n_\mathrm {dust} is the number density of dus...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.010228272527456284, -0.0007689319318160415, -0.038380809128284454, -0.017115766182541847, -0.030356841161847115, -0.019159896299242973, -0.017664935439825058, -0.03954016789793968, 0.019068367779254913, 0.03203485533595085, -0.004092071671038866, 0.01041895616799593, -0.017847992479801178...
b043ed6a788d6cd459929beda00b335ceaa2a8ab
subsection
21
47
Adsorption and desorption of CO and H
The cosmic-ray photodesorption rate , isk_\mathrm {cr-des,s} = f(70\,{\rm K})\,k_\mathrm {th-des,s}(70\,{\rm K})\,,where the fraction of time spent by the grain at 70 K is f(70\,{\rm K})=3.16\times 10^{-19}\zeta /\zeta _0, \zeta _0=1.3\times 10^{-17} s^{-1}, and \zeta is the cosmic ray ionization rate. Although for the...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ 0.005571187939494848, 0.0015273068565875292, -0.037700917571783066, -0.03937990590929985, -0.03730406612157822, -0.026497486978769302, 0.017751485109329224, -0.010272354818880558, 0.01620986871421337, 0.03800618648529053, -0.014805623330175877, -0.040204133838415146, -0.024116376414895058, ...
ccc556fbb9eafd7bc37e8780b2f1a45fbf8eff57
subsection
22
47
Implementation
The hybrid-characteristics method described for point-sources in and diffuse radiation in works well on patch-based hierarchical adaptive meshes. ramses, however, has a cell-based octree, based on the fully threaded tree by , and the “patches” that would be connected by short-characteristics rays, would consists of onl...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.005646908655762672, 0.002781484043225646, -0.0437406487762928, 0.020008372142910957, -0.014521712437272072, -0.03369830921292305, -0.00579571258276701, 0.011331972666084766, 0.030111759901046753, 0.04822765290737152, -0.04645727202296257, 0.023243896663188934, 0.03839898109436035, 0.052...
ef23179346eb1c9bca7d5238a69aa43388c2cd56
subsection
23
47
Ray Tracing
The radiation field is split into two components: A diffuse field for extended sources of emission, and a point source field. The diffuse field is discretised in solid angle into a set of equal-solid-angle directions using the healpix scheme , and for each direction into a set of parallel rays that cover the computatio...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.011217337101697922, -0.011865958571434021, -0.049356281757354736, 0.009790369309484959, 0.015750056132674217, 0.0042656403966248035, 0.011713341809809208, 0.030492842197418213, 0.016436832025647163, 0.03910043090581894, -0.004231301601976156, 0.0004955277545377612, -0.02606695331633091, ...
5c0d2c123e15524546834febd07e2c85405cb81e
subsection
24
47
Ray Tracing
Going from level \ell to \ell +1 we can proceed as just described. Lets label by d the distance from the ray plane cell centre to the projected cell centre in units of the cell size at level \ell , and the vector of indices at level \ell +1 by {i}_{\ell +1}=(2i, 2i+1)+q_{\ell +1}, whereq_{l+1}= {\left\lbrace \begin{arr...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.025738051161170006, 0.005141507834196091, -0.02952171303331852, -0.011923110112547874, -0.003619652008637786, 0.020047303289175034, 0.00955832190811634, 0.03393089771270752, 0.010931424796581268, -0.0016734692035242915, 0.006194219924509525, 0.02405981533229351, -0.019543832167983055, 0...
376630b7d08f30ae839f22ffd8dd86fe62c81f1d
subsection
25
47
Ray Tracing
We use the healpix nested pixel index as unique ray id for matching up ray points and load balancing rays.
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.02589035965502262, 0.01064144168049097, -0.018582474440336227, 0.011770425364375114, -0.021176086738705635, 0.007818980142474174, 0.06358928978443146, 0.031733617186546326, -0.005416073836386204, 0.017895929515361786, -0.04659349471330643, -0.028544997796416283, -0.018536703661084175, 0...
14cb39897cd895f105480457346fe3958a4beb45
subsection
26
47
Interpolation
When interpolating from cells to rays, we are interpolating in three dimensions from a uniform grid so we can get a second-order accurate, conservative interpolation with triangular-shaped cloud (TSC) interpolation. Where support points are missing, they are reconstructed from the eight surrounding parent cells using c...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.014255971647799015, 0.012638055719435215, -0.04603427276015282, -0.004682033322751522, -0.011630674824118614, 0.01272200420498848, 0.006303764414042234, 0.028985105454921722, -0.015545724891126156, 0.024436626583337784, -0.011340671218931675, -0.009776176884770393, 0.00992881041020155, ...
857dadbf8b7d3eb9ed3887610304d60c6677102e
subsection
27
47
Interpolation
Selected results are summarised in Tab. REF . Ray discretisation and error for tests I3 and I8 are shown in Fig. REF .Based on these tests, we choose to use the unstructured variant of TSC interpolation in the plane perpendicular to the main ray direction and the R1 coverage strategy. [Table: Summary of tests of interp...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.05300459265708923, -0.011374473571777344, -0.028501030057668686, -0.030438734218478203, 0.010291190817952156, 0.02395429089665413, 0.010779431089758873, 0.026517553254961967, 0.0008110320195555687, 0.0316745899617672, -0.01010810025036335, -0.012129721231758595, 0.02944699488580227, 0.0...
ae9c7c5cb601d3b72283a6f4e23cf797e780dc71
subsection
28
47
Parallelisation
The ramses grid is distributed over different MPI ranks, and when constructing the hash table of rays in Sect. REF , we need to merge them before constructing ray points. This is done by extracting an array of the keys and values on each rank, gathering them on a single master rank, inserting them into the master rank'...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ 0.02908928692340851, -0.010822678916156292, -0.04631099849939346, 0.0351145975291729, -0.004824062343686819, 0.003212863579392433, 0.00836679246276617, 0.013766692019999027, 0.022911436855793, 0.04875162988901138, -0.01923523284494877, -0.0033005739096552134, -0.01210401114076376, 0.044846...
bf9d21ac88531e36cde917cd3b92be4095e9f77d
subsection
29
47
Scaling considerations
As described, each rank must have access to a global hash table of all rays. Inevitably, for a large enough number of ranks, merging of tables will dominate computational time, and holding the table will dominate memory usage. Here we describe a way to solve this problem. The method is however not currently implemented...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ 0.03799523785710335, -0.01605260744690895, -0.04446510970592499, 0.02282766066491604, -0.00808733981102705, 0.012718486599624157, 0.016922377049922943, -0.004821885842829943, -0.013809514231979847, 0.015838978812098503, -0.03704917058348656, 0.00726716173812747, 0.011696124449372292, 0.045...
764991fcdf73275507193b26629d67a26789e0f5
subsection
30
47
Boundary conditions
We have implemented the following boundary conditions for the radiation. A prescribed incoming intensity (I(0)=I_{0}, I(L)=I_{L}), which is useful in test problems, radiative equilibrium (I(0)=S(0), I(L)=S(L)), and periodic boundaries for the radiation. Periodicity is useful in situations with periodic boundaries for t...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.01617598533630371, 0.007206706330180168, -0.0423322468996048, -0.014726249501109123, 0.0016118758358061314, -0.011368970386683941, 0.034854669123888016, -0.0008035534992814064, 0.019807951524853706, 0.033237069845199585, -0.04910784587264061, -0.025225378572940826, 0.018205612897872925, ...
7bebbdc3d1169cbbae0b39799c2334ebe015d4be
subsection
31
47
Tests
lampray is applied to a set of test problems where the result can be compared to a well-known analytical solution or to other established codes. The tests include the expansion of an HII region around a new star (Test 1), trapping of an ionization front by a dense clump of gas (Test 2), photo-evaporation of a dense clu...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ 0.0004222594725433737, 0.01834193989634514, -0.01985263265669346, 0.010994482785463333, -0.02948138862848282, -0.018570832908153534, -0.02388114482164383, 0.04623633995652199, -0.003563097445294261, 0.033265747129917145, -0.04809799790382385, -0.01116233691573143, -0.006271661724895239, 0....
924951065c045d9fd0c41463bfda7ce4dd804981
subsection
32
47
TEST 1: HII region expansion
The cosmological code comparison papers and include a series of four tests with the expansion of an HII region around a point source. We reproduce three of these here, starting with a monochromatic source in an isothermal, static, uniform density medium, then replacing the source with a T=10^5 K black body and includin...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.0006832400686107576, -0.007529467344284058, -0.04235420748591423, -0.015776026993989944, -0.0015104706399142742, -0.05440745875239372, -0.012022736482322216, -0.0053591192699968815, -0.010207120329141617, 0.017057638615369797, -0.04305604100227356, -0.00533241918310523, -0.019956521689891...
416c84458d6197f83e7783cb809aac3188819c43
subsection
33
47
TEST 1.1: Isothermal gas
The first test reproduces Test 1, which has monochromatic radiation with photon energy 13.6 eV, is isothermal at T=10^4 K, has box length L=6.6 kpc, and is resolved by 128^3 cells. At the final time, the ionization front is spherical (Fig. REF ) with ionization structure in good agreement with the benchmark codes. The ...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.04929638281464577, -0.034309063106775284, -0.047037601470947266, -0.023274607956409454, 0.006066660396754742, -0.028066888451576233, -0.022496243938803673, 0.014094492420554161, 0.00042376003693789244, 0.02982202358543873, 0.006951858755201101, -0.02434295043349266, -0.006036136299371719,...
2a428421875c30ef07fc804fed5244c92b372cbd
subsection
34
47
TEST 1.2: Non-isothermal gas
The second test reproduces Test 2, which has initial temperature T=100 K and includes heating and cooling. The box length is still L=6.6 kpc. Again, the ionization structure agrees well, especially with the ray tracing codes (Fig. REF ), and the temperature structure is similar to that of especially rsph, with signific...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.015622102655470371, -0.01842919923365116, -0.04384562745690346, 0.041709791868925095, 0.008726408705115318, -0.06328172236680984, -0.018063055351376534, -0.005301445722579956, 0.0021758812945336103, 0.030633965507149696, -0.0045233918353915215, -0.015698382630944252, -0.015187307260930538...
bf977a15b274fa4ecf9cf8e0a0f986d335599528
subsection
35
47
TEST 1.3: Hydrodynamics
The third test reproduces Test 5. It has the same parameters as Test 1.2, except that the box length is L=15 kpc and hydrodynamics is included. The position of the ionization front (Fig. REF ) follows the agreement of all the benchmarked codes except Enzo, which is monochromatic. In density and Mach number, the double ...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
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8e0a8aa046629eb37d57047882c41626ad985078
subsection
36
47
TEST 2: ionization front trapping by a dense clump
This test is a replication of Test 3 from the code comparison paper . It tests hydrogen photo-ionization chemistry and related heating and cooling processes, as well as the diffusivity of radiation transport and ability to form a shadow. The setup is briefly repeated here. The simulated volume is resolved by 128^3 cell...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.021969478577375412, -0.025066565722227097, -0.04961440712213516, -0.008558942936360836, -0.005194866564124823, -0.05846322700381279, -0.042962536215782166, 0.023586677387356758, -0.009573506191372871, 0.02259499952197075, -0.01659916155040264, -0.023723985999822617, -0.03615809977054596, ...
09a77ba5a73a8fbe55da6e0670e2f915d8a65510
subsection
37
47
TEST 3: Photo-evaporation of a dense clump
This test corresponds to Test 7 from the code comparison paper . It is identical to the above test, except hydrodynamics is included, allowing the clump to evaporate. At 1 Myr, the gas is still almost static, and the structure resembles the previous test, with virtually no flaring from the ionization front (Fig. REF )....
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.05228126049041748, -0.012948233634233475, -0.03604446351528168, -0.030184568837285042, 0.001862691598944366, -0.05658462271094322, -0.00585226621478796, 0.030138788744807243, 0.0017882983665913343, 0.03381648287177086, -0.01820535399019718, -0.03311451897025108, -0.02012813277542591, 0....
d83e1ec4a3c79cf89945166436f20001c162eaab
subsection
38
47
TEST 4: Plane-parallel PDR
A motivation for developing the present method is to study the effect of the interstellar radiation field on molecular clouds. Therefore we wish to test it on the case of a PDR. The problem is so rich in micro-physical processes that no consensus solution exists, even in the simplified case of a uniform density, plane ...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.01408061757683754, 0.0025819551665335894, -0.03960268944501877, -0.04533867537975311, 0.002675393596291542, -0.021723510697484016, 0.026513665914535522, -0.005446132738143206, -0.007185233756899834, 0.04710828512907028, -0.062272027134895325, -0.004012137185782194, -0.021616723388433456, ...
46926d96e300335ed7a5430c4d165a2f42424513
subsection
39
47
TEST 4: Plane-parallel PDR
REF ) as is used in . The ionization transition to H+ and He+, and the dissociation transition for H2 agrees well with Richings' result (Fig. REF ). There is roughly a 50% deviation in the optically thin ionization degree of He+, which is due to the coarseness of frequency bins. The locations of the molecular transitio...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.015554765239357948, -0.02349616214632988, -0.045985348522663116, 0.021711064502596855, -0.0016239434480667114, -0.023709764704108238, -0.039973992854356766, 0.03667842596769333, -0.0053705512546002865, 0.04253720864653587, -0.03231485188007355, -0.011641280725598335, 0.033504918217659, ...
51ce581efc38287c33f221764e9ffc4d398fadb3
subsection
40
47
TEST 4: Plane-parallel PDR
In the top panel are shownH2: n_{{H2}} / n_{{H}_\mathrm {tot}}, CO: n_{{CO}} / n_{{C}_\mathrm {tot}}, OH: n_{{OH}} / n_{{O}_\mathrm {tot}} and H2O: n_{{H2O}} / n_{{O}_\mathrm {tot}}.In the lower panel are shown E: n_{{e-}} / n_{{H}_\mathrm {tot}}, H: n_{{H}} / n_{{H}_\mathrm {tot}},H+: n_{{H+}} / n_{{H}_\mathrm {tot}},...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.003982649650424719, 0.010246548801660538, -0.04763920605182648, 0.014427568763494492, 0.010673807002604008, -0.051454003900289536, -0.026184778660535812, 0.011947949416935444, -0.012108171358704567, 0.051423486322164536, -0.023224493488669395, -0.028885655105113983, 0.027085071429610252, ...
489ad82a6cf308bd2c528e9dde9c8433070d7bc9
subsection
41
47
TEST 4: Plane-parallel PDR
They are similar to the previous test in that they use constant pressure, with n T=10^3\, \mathrm {K}\, \mathrm {cm}^{-3} as a model for an ISM in pressure equilibrium, except that at high densities a temperature floor is imposed at T=10\, \textrm {K} for the gas temperature, to emulate an isothermal molecular cloud. T...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.006656200159341097, 0.01586807519197464, -0.04375927150249481, -0.033689144998788834, -0.006980427540838718, -0.026792636141180992, 0.03576420247554779, -0.012000232003629208, -0.013464977964758873, 0.04903845861554146, -0.04974031448364258, 0.022169532254338264, -0.013426832854747772, ...
cc3bc65132f14fc7d30c1bcce17590a7d9c61248
subsection
42
47
TEST 5: Spherical PDR
The final PDR test uses the same density and temperature profile as above, but with r being the radius in a spherically symmetric cloud. 192 healpix directions are used (N_\mathrm {side}=4), with outflow boundaries for the radiation on all faces. The emission is set such that we get one Black flux at a distance of r_0+...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.019556721672415733, 0.00980887096375227, -0.020441504195332527, -0.04854094609618187, -0.005411659367382526, 0.010716535151004791, 0.012333549559116364, -0.028968967497348785, 0.007551152724772692, 0.032248761504888535, -0.010891965590417385, 0.010968239977955818, -0.04732055589556694, ...
4749559ea6caeda2eec094c5de3ff6173c6399f5
subsection
43
47
TEST 5: Spherical PDR
In the 1D solution, Eqn.() is used to account for the clouds spherical shape.][Figure: Test 5: Same as Fig. , but with two extra adaptive mesh levels. Refinement is applied where the relative gradient in H, H+ or H2 exceeds 0.2, and the abundance of that species is above 1% by mass.]The test is repeated with two additi...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.010536364279687405, -0.008560318499803543, -0.04773026332259178, -0.0222476739436388, -0.008491653017699718, -0.026474427431821823, -0.004604414105415344, 0.031174208968877792, -0.003162435023114085, 0.010536364279687405, -0.03778137266635895, -0.009460601955652237, 0.0018167789094150066,...
9db80d41e5efcc485150207085d3ad1ed2c7e236
subsection
44
47
Performance and scaling
The weak-scaling properties of the photo-chemistry solver with krome are measured on the spherical cloud setup of Test 5, except using 48 healpix directions instead of 192. The test is performed on the local HPC cluster at University of Copenhagen using nodes with 2x 10-core Xeon E5-2680v2 running at 2.8 GHz with 64 GB...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.04939568042755127, -0.009259783662855625, -0.0350559838116169, -0.003047185717150569, 0.0032760107424110174, -0.009679296053946018, -0.009038586169481277, 0.013935440219938755, 0.010022533126175404, 0.02181464619934559, -0.03810698539018631, -0.0006087697693146765, -0.020929856225848198, ...
870e453eb39d3a8c250183ad6a78def53b7190d8
subsection
45
47
Summary and future work
We have presented a new method we call lampray, and its implementation into the ramses code, for solving the time-independent radiative transfer problem on an adaptive octree mesh by means of tracing rays, that each cover the entire length of the domain. The diffuse radiation field is represented by rays that uniformly...
{ "cite_spans": [] }
1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
[ -0.01771717704832554, -0.009629231877624989, -0.049717966467142105, 0.0067641157656908035, -0.018770135939121246, -0.0547538585960865, -0.001061542658135295, 0.02064714953303337, 0.02513366937637329, 0.06329961121082306, -0.03927994146943092, 0.0011368902632966638, 0.009659752249717712, 0....
8edb1195b1ff6d666fae4cdbff85c6deec7401cc
subsection
46
47
Summary and future work
Electron and OH density in the optically thick part differs due to the omission of metals that would donate electrons if included.A new method for including an interstellar radiation field in periodic boundary gas simulations has been presented, in which the interstellar field is modelled as an emissivity in the diffus...
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1809.05541
Lampray: Multi-group long characteristics ray tracing for adaptive mesh radiation hydrodynamics
[ "Troels Frostholm", "Troels Haugbølle", "Tommaso Grassi" ]
[ "astro-ph.SR", "astro-ph.GA" ]
2,018
en
Physics
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adfff87b06630d728c81ed85c0833f7ed08fb101
abstract
0
56
Abstract
Long before we learn to construct the field of rational numbers (out of the ring of integers) at university, we learn how to calculate with fractions at school. When it comes to "numbers", we are used to a commutative multiplication, for example 2*3=6=3*2. On the other hand --even before we can write-- we learn to talk...
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
[ -0.017033211886882782, 0.029350239783525467, -0.027854492887854576, 0.011653098277747631, 0.004968020599335432, -0.05515952780842781, 0.025732971727848053, 0.007829783484339714, 0.03272330388426781, 0.017567409202456474, -0.025229301303625107, -0.03342539072036743, -0.053999558091163635, 0...
0868beff054e4161b796599de7f7856f90a6eeb5
subsection
1
56
Introduction
Since most of the literature on free fields is almost inaccessible without a degree in mathematics and difficult without a specialization in algebra we want to provide an introduction with focus on the application. One of the main hurdles is the huge number of concepts and definitions (for precise formulations), needin...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1017/cbo9780511542794", "end": 720, "openalex_id": "https://openalex.org/W574556491", "raw": "P. M. Cohn. Free ideal rings and localization in general rings, volume 3 of New Mathematical Monographs. Cambridge University Press, Cambridge,...
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
[ -0.02123115211725235, 0.019414827227592468, -0.03751701861619949, 0.02579485811293125, 0.017690083011984825, -0.048323385417461395, 0.08608461171388626, 0.02149062789976597, 0.03623490780591965, 0.01939956471323967, -0.0220553670078516, -0.03257173299789429, -0.027855394408106804, 0.031900...
553ffa28213f1b070dac27709a24e77b40156f33
subsection
2
56
Representing Elements
First of all, we need a suitable representation for the elements in the free field \mathbb {F} = \mathbb {K}(\!\langle X\rangle \!) of the free associative algebra \mathbb {K}\langle X\rangle over the commutative field \mathbb {K} (for example the rational numbers \mathbb {Q} or the real numbers \mathbb {R}) and the (f...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.4153/cjm-1994-027-4", "end": 533, "openalex_id": "https://openalex.org/W2331768386", "raw": "P. M. Cohn and C. Reutenauer. A normal form in free fields. Canad. J. Math., 46(3):517–531, 1994.", "source_ref_id": "9ffe20691e2acb3bb357...
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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b49e9f772b3443f42989c07dd46247b9f026ea7e
subsection
3
56
Representing Elements
So here we could write \pi _r = (1, a, v).)For the polynomial f = xy+yx-yz \in \mathbb {K}\langle X\rangle an ALS \mathcal {A}_f = (u,A,v) of dimension n=4 is (the zeros are replaced by lower dots to emphasize the structure)\begin{bmatrix} 1 & -x & -y & . \\ . & 1 & . & -y \\ . & . & 1 & z-x \\ . & . & . & 1 \end{bmat...
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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f6550376f1973b72b34519a0b2c73f06519d55b3
subsection
4
56
Representing Elements
A (square) matrix A \in R^{n \times n} is called full, if A = PQ with P \in R^{n \times m} and Q \in R^{m \times n} implies m \ge n . To show that the full matrices over the free associative algebra are those which are invertible over the free field (and vice versa) is very difficult. For details we refer to . Importan...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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a313c102fd9d9f4ecedc6f8a4243e2ce43e80087
subsection
5
56
Free Fractions
The main idea (of free fractions) is as simple as in the usage of “classical” fractions (for elements in \mathbb {Q}): calculating, factorizing and minimizing (or cancelling), for example&\frac{2}{3} \cdot \frac{3}{4} = \frac{6}{12} = \frac{2\cdot 3}{2\cdot 2 \cdot 3} = \frac{1}{2}\quad \text{or}\\ &\frac{1}{2} + \frac...
{ "cite_spans": [ { "arxiv_id": "", "doi": "10.1515/math-2020-0076", "end": 1435, "openalex_id": "https://openalex.org/W3108660119", "raw": "K. Schrempf. A Standard Form in (some) Free Fields: How to construct Minimal Linear Representations. ArXiv e-prints, March 2018.", "sourc...
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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fc9066905dce9e3bfa0ea83f382eee6efb043447
subsection
6
56
Free Fractions
If we describe (elementary) transformations in the following, they always refer to the system matrix A.\underbrace{\begin{bmatrix} \underline{1} & \underline{0} & \underline{0} & \underline{0} \end{bmatrix}}_{\mathbox{2cm}{u, left hand side}} = \underbrace{\begin{bmatrix} t_1 & t_2 & t_3 & t_4 \end{bmatrix}}_{\mathbox{...
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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2e376fee529f699c7ec80dc18b601e6bed338e2e
subsection
7
56
Free Fractions
In this case we say “f is of type (*,1)” or 1 \in L(f) if 1 \in L(\mathcal {A}) respectively “f is of type (1,*)” or 1 \in R(f) if 1 \in R(\mathcal {A}).Now we will transform this representation step by step such that the solution of both systems of equations, that is, the computation of s and t, becomes easier. Those ...
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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c98b9943351b0e56c5e7cac9e0840a7fe0c43445
subsection
8
56
Free Fractions
Either by factorization (Section ) or by “abstract” refinement (Section ). But we should not worry here. The examples in the beginning are such that we can easily minimize them by “hand” respectively check their minimality.A last note concerning the system matrix A. We always write it in the compact form with (at most)...
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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62d5a01d5f44063cf47c053f9fc3e08e355bc8e9
subsection
9
56
Left and Right Minimization Steps
For practical computations we repeatedly have to make admissible linear systems smaller. In concrete situations it is possible to minimize them. Later, in Section  we will see that there are some subtle details behind the rather simple looking (left and right) “minimization steps”. Let us take a closer look on the exam...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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ae48e4746e8341c664e5963a31aa3ce97f488e76
subsection
10
56
Left and Right Minimization Steps
For the inverse we use the minimal inverse (Theorem REF ). And finally, using the multiplication (Proposition REF ) we obtain an ALS of dimension 5 for f f^{-1}. for f f^{-1}= 1 with f = xy - z,\mathcal {A} = \left( \begin{bmatrix} 1 & . & . & . & . \end{bmatrix}, \begin{bmatrix} 1 & -x & z & . & . \\ . & 1 & -y & . & ...
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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bad9f6884b292cb88fc1d64ba908c6e8814434a6
subsection
11
56
Left and Right Minimization Steps
Given an ALS \mathcal {A} = (u,A,v) with v = [0,\ldots ,0,\lambda ]^{\!\top } we write also write \mathcal {A} = (1,A,\lambda ).Remark. The other case f^{-1}f = 1 is somewhat more difficult because we must not change the first component in the left family. The trick here is, to work with an “extended” ALS for 1 \cdot f...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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6c27c4d77f73692fb693f87dce4efd162016968a
subsection
12
56
Calculating
One of the main parts of this section is the construction of a minimal admissible linear system for the inverse (of an element in the free field) in Section REF . The following (simple) construction (of an ALS for the inverse) is from Proposition REF . We assume that we have given the inverse of a monomial f = xyz by t...
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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8133a29fe6e3980e9548ace15e4dd7df3b8ac797
subsection
13
56
Calculating
We denote by I_n the identity matrix and \Sigma _n the permutation matrix that reverses the order of rows/columns (of size n) respectively I and \Sigma if the size is clear from the context.
{ "cite_spans": [] }
1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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f083ef7be5fd65faa084efac9c3b522b70946229
subsection
14
56
Preliminaries
Let \mathbb {K} be a commutative field, \overline{\mathbb {K}} its algebraic closure and X = \lbrace x_1, x_2, \ldots , x_d\rbrace be a finite (non-empty) alphabet. \mathbb {K}\langle X\rangle denotes the free associative algebra (or free \mathbb {K}-algebra) and \mathbb {F} = \mathbb {K}(\!\langle X\rangle \!) its uni...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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e7ee69d704fdbfa5defc7b47e7518d8eb9262a6b
subsection
15
56
Preliminaries
A linear representation of f is a triple \pi _f = (u,A,v) with u \in \mathbb {K}^{1 \times n}, full A = A_0 \otimes 1 + A_1 \otimes x_1 + \ldots + A_d \otimes x_d, that is, A is invertible over \mathbb {F}, A_\ell \in \mathbb {K}^{n\times n}, v \in \mathbb {K}^{n\times 1} and f = u A^{-1}v. The dimension of \pi _f is \...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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a051478ce3996bd6d44820d7190ea04ddc3edea2
subsection
16
56
Preliminaries
The following definition is a special case of the more general admissible systems and the slightly more general linear representations .Definition 2.6 (Admissible Linear Systems, Admissible Transformations ) A linear representation \mathcal {A} = (u,A,v) of f \in \mathbb {F} is called admissible linear system (ALS) f...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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20b927f66c6c6b6a4a21a67104025e1711e6c333
subsection
17
56
Preliminaries
An admissible transformation (P,Q) for an ALS \mathcal {A} is called polynomial if it has the form(P,Q) = \left( \begin{bmatrix} 1 & \alpha _{1,2} & \ldots & \alpha _{1,n-1} & \alpha _{1,n} \\ & \ddots & \ddots & \vdots & \vdots \\ & & 1 & \alpha _{n-2,n-1} & \alpha _{n-2,n} \\ & & & 1 & \alpha _{n-1,n} \\ & & & & 1 \e...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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245012236c5a04c28f1ca83ab14774bb69ea3f4a
subsection
18
56
Minimal Systems
The main idea is to start with minimal admissible linear systems and construct minimal ones for the rational operations (scalar multiplication, sum, product, inverse). We already have seen the minimal monomial:Proposition 2.9 (Minimal Monomial ) Let k \in \mathbb {N} and f= x_{i_1} x_{i_2} \cdots x_{i_k} be a monomial...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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39453bc2a4b3bd032725d25ffb0a89fb82406b93
subsection
19
56
Rational Operations
“Basic” rational operations (on the level of admissible linear systems) are easy to formulate. For the multiplication we can provide alternative constructions yielding minimal admissible linear systems immediately in special cases, for example the minimal polynomial multiplication (Proposition REF ).Proposition 2.10 (R...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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5b034ee895d3e560807b23631f13b9c9c831ad21
subsection
20
56
Rational Operations
Then there exists an admissible transformation (P,Q) such that the first column of PAQ is [1,0,\ldots ,0]^{\!\top } and Pv = [0,\ldots ,0,\lambda ]^{\!\top } for some \lambda \in \mathbb {K}.Proposition 2.12 (Multiplication Type (*,1) ) Let f,g\in \mathbb {F} \setminus \mathbb {K} be given by the admissible linear sys...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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1817920fd3e6fe082dc0f732927bc5dcd6cd8103
subsection
21
56
Disjoint Addition
For disjoint elements f,g \in \mathbb {F} , that is, \operatorname{rank}(f+g) = \operatorname{rank}(f) + \operatorname{rank}(g), the addition from Proposition REF is minimal. For further details we refer to the remarks after . An important result of Cohn and Reutenauer is the primary decomposition (of elements in the f...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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f43d099a11696fb89ea6e9bbb0c99047055c66ac
subsection
22
56
Minimal Inverse
The derivation of the minimal inverse in consists of two major steps (motivated in the beginning of this section): keeping the form for f = (f^{-1})^{-1} and distinguishing different cases to ensure minimality. Notice especially the remark before how to transfer admissible linear systems into the appropriate form.The...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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66948dff221090c6bcc711cc3805c1dc8d009a16
subsection
23
56
Minimal Inverse
\\ -\lambda b & -b^{\prime }\Sigma & -a \\ . & . & 1 \end{bmatrix}, 1 \right) \quad \text{for}\quad \mathcal {A} = \left(1, \begin{bmatrix} a & b^{\prime } & b \\ a^{\prime } & B & b^{\prime \prime } \\ . & . & 1 \end{bmatrix}, \lambda \right).f of type (0,0) yields f^{-1} of type (1,1) with \dim (\mathcal {A}^{\prime ...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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4a96aa8e8d021191b60991758531463c94deb6a9
subsection
24
56
Rational Identities
Using the minimal inverse (Theorem REF ) and the rational operations (Proposition REF ) one can already show non-trivial rational identities very systematically by “hand”. The following proof is from .Example 2.14 (Hua's Identity ) We have:x - \bigl (x^{-1}+ (y^{-1}- x)^{-1}\bigr )^{-1}= xyx.Minimal admissible linear ...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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285a53b65b8c71ec786166018f9dd3356ba03f2a
subsection
25
56
Rational Identities
\\ -1 \end{bmatrix}, \quad s = \begin{bmatrix} x^{-1}+ (y^{-1}-x)^{-1}\\ (y^{-1}-x)^{-1}\\ -(1-xy)^{-1}\end{bmatrix}.This system is minimal and —after adding row 3 to row 1 (to eliminate the non-zero entry in the right hand side)— we apply the (minimal) inverse of type (0,0):\begin{bmatrix} -1 & -1 & -x & . \\ . & -y &...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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d3c172e01b394c53b660985ef01d00f40ede49bb
subsection
26
56
Factorizing
Since the whole factorization theory originated from a “small” problem of the minimization of linear representations, it should lead as a thread through this section. Somehow this theory has become independent and is interesting now from a purely algebraic point of view since it enables to view the free field as a “rin...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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d371ba96543e05eb12aaeac011f3e644d796d0fe
subsection
27
56
Factorizing
And this upper right block of zeros is that one coming from multiplication (1,*), see also . This yields a “natural” correspondence between factorizations and upper right zero block structure in the system matrix (assuming zero entries in the corresponding components of the right hand side).In other words: One can find...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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fd0aa8e20ed0ec88646a4af159661abe9bcc3dec
subsection
28
56
Minimal Polynomial Multiplication
As an introduction one could take the multiplication of x and 1-yx using Proposition REF , see also . The following lemma is needed in Section REF and (the proof of) the following proposition.Lemma 3.1 () Let \mathcal {A} = (u,A,v) = (1,A,\lambda ) be an ALS of dimension n\ge 2 and \mathbb {K}-linearly dependent left...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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5414aed6e72c713bef406f87039225403b0a9008
subsection
29
56
Polynomial Factorization
The polynomial factorization theory depends on minimal (polynomial) admissible linear systems. How to obtain such systems directly is discussed in Section REF . How to construct them in general is discussed in Section REF .Remark. Notice that, although we use (general) admissible linear systems here to represent polyno...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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f85629adc6f17ae549fd89798a7b12a875342120
subsection
30
56
Factorization Theory
The general factorization theory is somewhat difficult. Although it seems to be clear from the polynomials how it should be, the path to the divisibility equivalence (Theorem REF ) is long and stony. One needs a notion of left (respectively right) divisibility on the level of minimal admissible linear systems. This is ...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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236b9761b4bcee55fe39b4982a74a1370a5b3017
subsection
31
56
Minimal Factor Multiplication
Given two minimal admissible systems, under which conditions are the multiplications from Proposition REF and REF minimal? A special case is the minimal polynomial multiplication (Proposition REF ). The general answer is given in within the (framework of the) general factorization theory.
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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11080e6cdb606c72941b3d53a716a5b85ba37e61
subsection
32
56
General Factorization
Like in the general (minimal) multiplication in the previous subsection we have to distinguish several cases for the factorization . Looking for zero (lower left and upper right) blocks (of appropriate size) in the system matrix of a minimal ALS (similar to the polynomial factorization) is rather natural when we want t...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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178e7bfd601c4cb92c3c06d5300f99991482119c
subsection
33
56
Examples Factorization
Polynomial factorization is illustrated in detail (step by step) in . The general factorization (of a regular element) is discussed briefly in .
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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8599ff8e6148c858cd71ef4617d0d2dad4a85405
subsection
34
56
Minimizing
The basic idea of the minimization (of a linear representation) with left and right minimization steps is surprisingly simple. If the block structure becomes coarser and a “look” is not sufficient any more, row and column transformations can be found by solving a linear system of equations. That is the essential conten...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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3fb89e462d8afe248bc94753c414288278274b28
subsection
35
56
Preliminaries and a Standard Form
To be able to formulate statements —in particular for the minimization— in a convenient way, we need some notation which formalizes what we have already used, namely to describe an ALS (and admissible transformations) in terms of block rows and columns instead of (single) rows and columns. Then it is possible to define...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
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en
Mathematics
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bc14e99be274f4b304b3d996437098b728f4517f
subsection
36
56
Preliminaries and a Standard Form
The admissible linear system \mathcal {A} is called refined if all pivot blocks are refined.Definition 4.3 (Standard Admissible Linear System ) A minimal and refined ALS \mathcal {A} = (u,A,v) = (1,A,\lambda ), that is, v = [0,\ldots , 0, \lambda ], is called standard.Remark. For a polynomial p given by a standard ALS...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
2,018
en
Mathematics
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d17803801fa558b0c536ede2057a9b12854159f0
subsection
37
56
The Word Problem
One of the difficulties in free fields is (that of) the word problem, that is, to check whether two admissible linear systems represent the same element. A solution to the word problem is . Unfortunately it is hard to apply practically already for systems of dimension 3. If those systems are given by minimal admissible...
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1809.05425
Free Fractions: An Invitation to (applied) Free Fields
[ "Konrad Schrempf" ]
[ "math.RA" ]
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en
Mathematics
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