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87012884498fb48826d12895df5cffe420c5fccc
subsection
17
31
Cutoff Frequency and Diffusion Coefficient
If the cutoff frequency is about 10^{18} Hz instead of 10^{17} Hz, then \bar{\kappa } \le (0.5–2.3) \bar{\kappa }_{\rm B}. In each of these cases, the highest-energy electrons have diffusion coefficients nearly as small as the Bohm coefficient (i.e., are being accelerated about as fast as possible).Similar results for...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 123, "openalex_id": "", "raw": "Rothenflug, R., Ballet, J., Dubner, G., Giacani, E., Decourchelle, A., & Ferrando, P. 2004, , 425, 121", "source_ref_id": "9a2da5bf38a6cccda543793719a7d08dab8e785f", "start": 0 }, ...
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.010271136648952961, 0.007989509031176567, -0.06028378754854202, -0.018878744915127754, 0.01085108146071434, -0.02878360077738762, -0.011095269583165646, 0.03711649775505066, 0.009424110874533653, 0.034766193479299545, -0.03559032827615738, 0.026418033987283707, 0.012041496112942696, -0....
cf55c0576a08a5cb69c94cb1ed8e4b2edc11ae6c
subsection
18
31
Cutoff Frequency and Diffusion Coefficient
There are at least three explanations for this apparent dilemma. One explanation is that, near the shock, B_{1} may be amplified by cosmic-ray streaming , , . For example, equation (15) of yields B_{1} = 30 \mu G (see Ksenofontov et al. 2005) and, hence, \kappa _{1} \sim \kappa _{\rm B,1}, if the upstream mass density ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 158, "openalex_id": "", "raw": "Lucek, S. G. & Bell, A. R. 2000, , 314, 65", "source_ref_id": "a8b35a61be7370bd51814d9fdc6a73ffe2effc3e", "start": 65 }, { "arxiv_id": "", "doi": "", "end": 158...
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.05317160487174988, -0.0005665889475494623, -0.03388087451457977, -0.03525442257523537, 0.009225670248270035, -0.01933651603758335, -0.016574157401919365, 0.019794365391135216, 0.01585685834288597, 0.009263824671506882, -0.014063614420592785, 0.026265308260917664, -0.01846660114824772, -...
06cef986696944fe2cb1c79a46a76bc38000b19c
subsection
19
31
Cutoff Frequency and Diffusion Coefficient
Therefore, the limit only applies to electrons at the cutoff momentum [i.e., \bar{\kappa } = \bar{\kappa }(p = p_{m})]. An advantage to using this momentum is that the limit does not depend on the functional form of \bar{\kappa }(p).4. The limit is based on the assumption that the cutoff is due to synchrotron losses. I...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1040, "openalex_id": "", "raw": "Blondin, J. M., & Ellison, D. C. 2001, , 560, 244", "source_ref_id": "b3dad069b3004ffad0412e97d77afebadfae0c6a", "start": 891 }, { "arxiv_id": "", "doi": "", "...
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.022247355431318283, -0.019790686666965485, -0.033325258642435074, -0.005561838857829571, -0.010223407298326492, 0.0034675663337111473, -0.018783604726195335, 0.030456598848104477, 0.01229860633611679, 0.008438126184046268, -0.044799886643886566, 0.021331826224923134, -0.005702983122318983...
6db48c40da24391a113d176a627d0f9d4b1f1948
subsection
20
31
Conclusions
We have performed a joint spectral analysis of some Chandra ACIS X-ray data and MOST radio data for 13 small regions along the bright northeastern rim of the supernova remnant SN 1006. The data were fitted with a model that includes a synchrotron emission component. This component is based on an electron spectrum that ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 849, "openalex_id": "", "raw": "Ellison, D. C., Berezhko, E. G., & Baring, M. G. 2000, , 540, 292", "source_ref_id": "71dfb974ea4bced362e0bffed26082fb9fd0b08f", "start": 689 }, { "arxiv_id": "", "do...
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.04051608219742775, 0.021020768210291862, -0.014369784854352474, -0.034200698137283325, -0.0017066026339307427, -0.05482484772801399, 0.0031100211199373007, 0.00019783242896664888, 0.041858479380607605, 0.023629294708371162, -0.005667064804583788, 0.020410586148500443, -0.02513949573040008...
9d9c77d80f66afdda6326c7cdd0784f8e6f8d36c
subsection
21
31
Conclusions
This result implies that at least some of the highest-energy electrons in SN 1006 diffuse close to the Bohm limit (i.e., are accelerated about as fast as possible), which provides additional support for the idea that Galactic cosmic rays are predominantly accelerated by the shocks of supernova remnants.We gratefully ac...
{ "cite_spans": [] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.04866359382867813, 0.031013505533337593, -0.01737549528479576, -0.035757824778556824, -0.027291275560855865, -0.04585666581988335, -0.014118543826043606, -0.027108214795589447, 0.04411758854985237, -0.00545367831364274, 0.01046496070921421, 0.022516446188092232, -0.032005082815885544, -...
834e5e0dec91edbccc8352b06161e97b6e5a1235
subsection
22
31
Diffusion coefficient
This appendix describes how measurements of or inferences about the shock velocity and cutoff frequency can be used to place an upper limit on the electron diffusion coefficient. Since the mean rate of synchrotron losses cannot exceed the mean rate of energy gains at momenta below the cutoff of the electron spectrum,\l...
{ "cite_spans": [] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.017485974356532097, -0.00991024449467659, -0.042143333703279495, -0.025221915915608406, 0.016570478677749634, -0.020735984668135643, -0.00745747797191143, 0.03683345764875412, 0.01101646851748228, 0.025069333612918854, -0.026564642786979675, 0.035399179905653, -0.03460574895143509, 0.02...
ccf4a016f27f2fb94bc0488359f9ec7b63b24e8e
subsection
23
31
Diffusion coefficient
If \sin \theta in equation (REF ) is replaced by the isotropic mean value of \pi / 4 and if \sin ^{2} \theta _{1} and \sin ^{2} \theta _{2} in equation (REF ) are replaced by the isotropic mean value of {2}{3}, then a combination of equations (REF ), (REF ), (REF ), and (REF ) yields\frac{\bar{\kappa }}{\bar{\kappa }_{...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1693, "openalex_id": "", "raw": "Stage, M. D., Allen, G. E., Houck, J. C., & Davis, J. E. 2006, Nature Phys., 2, 614", "source_ref_id": "044be8cd2ff9a4420af80de4af02957d65f40b16", "start": 1615 } ] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.03380850329995155, -0.013349476270377636, -0.02730921469628811, -0.05699845030903816, 0.025585224851965904, 0.004370999988168478, 0.001979536609724164, 0.03164207562804222, 0.013296078890562057, 0.014272497966885567, -0.02340354025363922, 0.025081759318709373, 0.002994096837937832, 0.00...
f4e778d7af36c0696035f1249d057c230f90f3a1
subsection
24
31
Diffusion coefficient
Equation () is similar to equation (22) of , equation (12) of , equation (A.4) of , and equation (22) of , except these authors use the peak frequency instead of the critical frequency. The latter three also use \sin \theta = 1 instead of \pi / 4.f1b.eps [f1b.eps] Color-coded ACIS image of the northeastern rim of SN 10...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 185, "openalex_id": "", "raw": "Aharonian, F. A., & Atoyan, A. M. 1999, , 351, 330", "source_ref_id": "0f0a5fd8bb59507752ef781111f10ac3c00c51b8", "start": 0 }, { "arxiv_id": "", "doi": "", "en...
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.035256270319223404, 0.009493246674537659, -0.0685589462518692, -0.03174590319395065, -0.020940087735652924, -0.04456636682152748, 0.020848512649536133, 0.014636693522334099, 0.020085390657186508, 0.03458471968770027, -0.022969992831349373, 0.036141492426395416, -0.0020260908640921116, 0...
34f9e43bfb56c59904519bf3ec4b49e37d3b77dc
subsection
25
31
Diffusion coefficient
Bottom: Differences between the data points and the solid line, divided by the uncertainties in the data points.f5.eps [f5.eps] X-ray emission profiles along a 49 -wide strip passing through region 6 toward the center of SN 1006. The black histogram in the top panel is the 2–7 keV ACIS data. For comparison, the black l...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 2178, "openalex_id": "", "raw": "Ellison, D. C., Berezhko, E. G., & Baring, M. G. 2000, , 540, 292", "source_ref_id": "71dfb974ea4bced362e0bffed26082fb9fd0b08f", "start": 2060 } ] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.024757886305451393, -0.040088556706905365, -0.05458023399114609, -0.030920663848519325, 0.018305277451872826, -0.039081767201423645, 0.0013814764097332954, 0.019586646929383278, 0.018884943798184395, 0.02280532382428646, -0.004641150590032339, 0.013973028399050236, 0.0013500141212716699, ...
5d8fc7ede1a3fb620e3c7b54d9534ed6ceefd21e
subsection
26
31
Diffusion coefficient
The red data points, which have similar confidence intervals, are the results obtained using the peak radio fluxes (Table ). The dashed line is the weighted mean value (4.98 \times 10^{16} Hz) of the black points. The corresponding 90% confidence level interval [(4.31–5.65) \times 10^{16} Hz] lies between the two dotte...
{ "cite_spans": [] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.05031140148639679, -0.03539188951253891, -0.0816454291343689, -0.011960017494857311, -0.002867963397875428, -0.03966332599520683, 0.06214937940239906, 0.032005250453948975, 0.015552599914371967, 0.04073118418455124, -0.02912203222513199, 0.03258494660258293, 0.0046833232045173645, 0.028...
0b68a52e758035513a88e2d8db13dfd5214b4b8c
subsection
27
31
Diffusion coefficient
1988; (4) Gardner & Milne 1965; (5) Kundu 1970; (6) Milne & Dickel 1975.ccccccccccc Best-Fit Parameters Using the Curved Model and “Cospatial” Radio Fluxes 0pt \alpha _{\rm X} \delta _{\rm X} \phi \zeta \nu _{\rm m}Region (J2000) (J2000) (deg) (\times 10^{-4}) \Gamma a a (10^{16} Hz) \chi ^{2}/{\rm do...
{ "cite_spans": [] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.06117274984717369, 0.020360391587018967, -0.07558070123195648, -0.0166973527520895, -0.004658927675336599, 0.033394705504179, 0.013377723284065723, -0.014476634562015533, 0.00434222724288702, 0.03427993878722191, -0.04133128747344017, 0.011080692522227764, -0.02136772684752941, 0.000480...
cb6027c4fe1e1a592a78003f76bf5779419b64ee
subsection
28
31
Diffusion coefficient
The uncertainties, which include only the statistical contributions, are reported at the 90% confidence level. These uncertainties were used to compute the weighted mean values of \Gamma and a. Units of right ascension are hours, minutes, and seconds, and units of declination are degrees, arcminutes, and arcseconds.a A...
{ "cite_spans": [] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.03296229988336563, 0.013238330371677876, -0.07666786760091782, -0.014611760154366493, -0.033603232353925705, -0.010071813128888607, 0.01881597936153412, 0.0028460503090173006, 0.005924820434302092, 0.016740575432777405, -0.05927109718322754, 0.03665529564023018, -0.018007181584835052, 0...
628094d12063015581fee4c27bd28467a409328c
subsection
29
31
Diffusion coefficient
Units of right ascension are hours, minutes, and seconds, and units of declination are degrees, arcminutes, and arcseconds.aThe curvature parameter was fixed at zero.ccccccccccc Best-Fit Parameters Using the Curved Model and Peak Radio Fluxes 0pt \alpha _{R} \delta _{R} \Delta \Psi \zeta \nu _{m}Region (J200...
{ "cite_spans": [] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.035253603011369705, -0.004940846003592014, -0.06672240793704987, 0.02193048968911171, -0.030782043933868408, -0.010835523717105389, -0.00818005669862032, 0.007420807611197233, 0.01811516471207142, 0.02089272066950798, -0.05371977761387825, 0.009736710228025913, -0.016955304890871048, -0...
67d88d3aeeb58f7f94823df28488c879ce7bb4cf
subsection
30
31
Diffusion coefficient
The uncertainties, which include only the statistical contributions, are reported at the 90% confidence level. These uncertainties were used to compute the weighted mean values of \Gamma and a. Units of right ascension are hours, minutes, and seconds, and units of declination are degrees, arcminutes, and arcseconds.a A...
{ "cite_spans": [] }
10.1086/589628
0807.1702
Evidence of a Curved Synchrotron Spectrum in the Supernova Remnant SN 1006
[ "G. E. Allen", "J. C. Houck", "S. J. Sturner" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.01820223592221737, -0.0004219661350362003, -0.06621769070625305, 0.0011757835745811462, -0.03908979892730713, -0.020048396661877632, 0.018659962341189384, 0.00030848823371343315, 0.009665646590292454, 0.022123422473669052, -0.0617930069565773, 0.027265209704637527, -0.01132108923047781, ...
69e328111dfe7e3eb1f518345e411bfc2fb84dd4
abstract
0
23
Abstract
(abridged) MHD turbulence is known to exist in shearing boxes with either zero or nonzero net magnetic flux. However, the way turbulence survives in the zero-net-flux case is not explained by linear theory and appears as a purely numerical result. Aims: We look for a nonlinear mechanism able to explain the persistence ...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.01556812971830368, -0.009877867065370083, -0.04289816692471504, -0.0029385702218860388, 0.033134713768959045, -0.00739886611700058, -0.03655192255973816, 0.059251949191093445, -0.002698297845199704, 0.0006392963696271181, -0.01197548396885395, -0.03655192255973816, -0.023630604147911072, ...
7d53e41e450eb28eb1fdbc20e80b93cec3b19d50
subsection
1
23
Introduction
The problem of angular momentum transport is a central issue of accretion disc theory. Following , angular momentum transport is often modelled assuming the disc is turbulent, using a kind of turbulent viscosity (the so-called \alpha model). However, the way discs may become turbulent is still a highly debated subject....
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 242, "openalex_id": "", "raw": "Shakura, N. I. & Sunyaev, R. A. 1973, , 24, 337", "source_ref_id": "f667a248c27df1979a5c54dac7b34be7ddc8da5b", "start": 87 }, { "arxiv_id": "", "doi": "", "end"...
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.003183655207976699, -0.010514264926314354, -0.045597419142723083, -0.022386685013771057, 0.01289485301822424, 0.0056844172067940235, -0.03137493133544922, 0.026140689849853516, 0.019304128363728523, 0.028857002034783363, -0.0317716971039772, 0.0002820749068632722, -0.027529366314411163, ...
6cc6b6ef49dea7ae8d9e13d43e5bad6b9a1b6a51
subsection
2
23
Introduction
Note also that studied this dynamo process in discs, using boundary conditions allowing for mean flux variations. Although a azimuthal field was generated in their simulations, no physical understanding of the underlying process was provided.In this paper, we describe a possible mechanism able to sustain MHD turbulence...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 114, "openalex_id": "", "raw": "Brandenburg, A., Nordlund, A., Stein, R. F., & Torkelsson, U. 1995, ApJ, 446, 741", "source_ref_id": "fc3a6b9e0e4e90fb7fe04d77992d6a440102f84f", "start": 0 } ] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.03203815594315529, -0.007940885610878468, -0.04930824786424637, 0.012563534080982208, 0.028315627947449684, -0.01450107991695404, -0.04409060627222061, 0.06273376196622849, 0.019360199570655823, 0.012784750200808048, 0.0018412404460832477, -0.01565292850136757, -0.039727311581373215, 0....
d768db86525bea37497ab03609ae40a521a8f196
subsection
3
23
Shearing-box equations and numerical method
MRI-related turbulence has been extensively studied in the literature. Therefore, we will recall here briefly the basic equations for the shearing-box model. The reader may consult , and for an extensive discussion of the properties and limitations of this model. Since MHD turbulence in discs is subsonic, we will work ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 265, "openalex_id": "", "raw": "Hawley, J. F., Gammie, C. F., & Balbus, S. A. 1995, , 440, 742", "source_ref_id": "5b82d5f5cbc6f3d1f310e288e29c08bb02da86f7", "start": 158 }, { "arxiv_id": "", "doi":...
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ 0.012794071808457375, 0.010818123817443848, -0.05337348207831383, -0.008170811459422112, 0.03369029238820076, 0.00844546128064394, -0.010886786505579948, 0.041502535343170166, 0.037016600370407104, 0.034819405525922775, -0.008666706271469593, -0.001422835048288107, -0.004039631225168705, 0...
3d2aaddf77f6886dd28a4ffa1023a06dce87f483
subsection
4
23
Shearing-box equations and numerical method
These may be written as {v}={u}-Sy{e_x}, leading to the following equations for {v}:\partial _t {v}+{\nabla \cdot }({v \otimes v})&=&-{\nabla } \Pi +{\nabla \cdot }({ B \otimes B})-Sy\partial _x {v}\\ & & +(2\Omega -S) v_y{e_x}-2\Omega v_x {e_y}+\nu {\Delta v},\\ \partial _t {B}&=&-Sy\partial _x {B}+SB_y{e_x}\\ & & +{\...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 633, "openalex_id": "", "raw": "Hawley, J. F., Gammie, C. F., & Balbus, S. A. 1995, , 440, 742", "source_ref_id": "5b82d5f5cbc6f3d1f310e288e29c08bb02da86f7", "start": 416 }, { "arxiv_id": "", "doi":...
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.03475179150700569, 0.004149467684328556, -0.03941994160413742, -0.02622402459383011, 0.030342981219291687, 0.02712409384548664, 0.03356187045574188, 0.04845113679766655, 0.021098211407661438, 0.04658997803926468, -0.025644319131970406, 0.010205859318375587, -0.0015217256732285023, 0.018...
a54663f5c832ea7be8d894b6135a1ab1a4367a82
subsection
5
23
Shearing-box equations and numerical method
One orbit corresponds to T_\mathrm {orb}=3\pi S^{-1}. [Figure: Fourier analysis of \widehat{B_x}(k_x=0,k_y=0,k_z=2\pi /L_z): amplitude (top panel) and phase (middle panel). This mode exhibits long-timescale (T\sim 50\, S^{-1}) cycles during which the phase is approximately constant. The transport coefficient (\alpha , ...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.017948074266314507, 0.01121754664927721, -0.06751894950866699, 0.02744101919233799, -0.003758259816095233, -0.019153770059347153, 0.0006348025053739548, 0.012774267233908176, 0.0025468410458415747, 0.02394602820277214, 0.004101654049009085, 0.021366756409406662, 0.02440388686954975, 0.0...
c79dde1324f23a3503e438bbc53f2d02dbd9581e
subsection
6
23
Long-timescale cycle in zero-net-flux MHD turbulence
The first zero-net-flux turbulent flow was computed by in the context of a stratified compressible shearing box. In this section we consider the simpler unstratified and incompressible case. The aspect ratio is set to L_y=L_z/2 and L_x=2L_z, which corresponds to the box used by elongated twice in the vertical direction...
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10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.04373101517558098, -0.003576223738491535, -0.030578143894672394, 0.01898164115846157, 0.017013289034366608, 0.04928513243794441, 0.004413536749780178, 0.047972895205020905, 0.013091839849948883, 0.028899701312184334, 0.030227195471525192, -0.0026416373439133167, 0.0017413825262337923, 0...
17cc98c057dc417290332c9017d480cb4e6fe370
subsection
7
23
Long-timescale cycle in zero-net-flux MHD turbulence
One easily observes the large-scale B_x(z) on the t=260 snapshot whereas strong nonaxisymmetric structures destroy the large scale structures at t=280.][Figure: Amplitude projected on \widehat{B_x}(k_0,t) (left) and phase (right) of the terms involved in equation (). The amplitude clearly shows one cycle comparable to ...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.034396227449178696, 0.01823579892516136, -0.04489516094326973, -0.023317405954003334, 0.0228901244699955, -0.0486186221241951, 0.029482480138540268, 0.014809910207986832, 0.02772757038474083, 0.015839966014027596, -0.006550390273332596, 0.007012007758021355, -0.030779587104916573, 0.007...
6e17d305dce9b66f66a4cc9d36fa3be15e079e0a
subsection
8
23
Cycle analysis
Naturally, one may wonder what mechanism generates this magnetic field structure, and whether this mechanism is related to some turbulent transport properties. To investigate these questions, we first reduce the Reynolds number of the simulation, keeping Pm constant. This allows us to have “cleaner” flows to work with,...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 467, "openalex_id": "", "raw": "Fromang, S., Papaloizou, J., Lesur, G., & Heinemann, T. 2007, , 476, 1123", "source_ref_id": "0acd280c16d155ce5ca19d197acb6dc0efa7003f", "start": 366 } ] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.028090709820389748, 0.01597554236650467, -0.03143230080604553, -0.016479069367051125, 0.007850445806980133, -0.05859224870800972, -0.004512671381235123, 0.03979390114545822, 0.03213418647646904, 0.03512483090162277, -0.03201211988925934, 0.03304969146847725, -0.016585879027843475, 0.016...
1f95b177192978eea8690cf213d2a31bf54d8805
subsection
9
23
Cycle analysis
The shear term is positive in the beginning of the cycle, but becomes negative for t>270, whereas the EMF has a systematic resistive effect, with a clear phase correlation between the EMF and the resistive term. According to these results, the long-timescale cycle in the azimuthal field comes from the behaviour of the ...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.04777314141392708, -0.012301965616643429, -0.0055671739391982555, -0.020391346886754036, 0.010775667615234852, -0.06208982318639755, -0.027366532012820244, 0.03806588426232338, 0.021475018933415413, 0.030877018347382545, 0.015270615927875042, 0.020513450726866722, -0.03232700005173683, ...
20fdc1fc31ac9c0690042989670d1ac51c82208c
subsection
10
23
Modal analysis of non axisymmetric structures
The EMFs described previously are obviously nonlinear terms, involving a coupling between {v} and {B}. An interesting question is therefore which modes contribute most to the EMFs observed in Figs REF –REF . In particular, one may wonder whether nonaxisymmetric structures play a role and if so, which structures are dom...
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10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
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6b6e3b67b15470262a41aec28f4bfd2f5a14505c
subsection
11
23
Modal analysis of non axisymmetric structures
REF . During one cycle, we note that the helicity associated with the vertical modes changes sign when B_y is reversed (t\simeq 270). Moreover, this reversal seems to be associated with an exchange of magnetic helicity between the nonaxisymmetric and the axisymmetric vertical modes. Note however that the total magnetic...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.055993687361478806, -0.015272392891347408, -0.023526502773165703, -0.02618124522268772, 0.006350782699882984, -0.017545705661177635, -0.03637301176786423, 0.05498671904206276, 0.03246718645095825, -0.004477969370782375, -0.01765250600874424, -0.0003225453838240355, 0.037196896970272064, ...
5f66709375fb1bf6c3937bf76c665df24c779c84
subsection
12
23
Model and equations
To understand the nonaxisymmetric origin of the EMF described previously, we consider a linear model including shearing waves in the presence of a background azimuthal magnetic field with a vertical structure, B_x^0(z). This vertical structure is required in order to compare the EMF generated by the perturbation with t...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 451, "openalex_id": "", "raw": "Balbus, S. A. & Hawley, J. F. 1992, , 400, 610", "source_ref_id": "5759034925171b42222007d8d6742731554946ab", "start": 350 }, { "arxiv_id": "", "doi": "", "end"...
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
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8e6cb6e7118b56b91607d8d276c69b34f47d83ea
subsection
13
23
Model and equations
Using these solutions in the evolution equations (REF )–(), one eventually finds:\partial _t {\bar{v}}&=&-(i{k}+{e_z}\partial _z)\bar{\Pi }+(2\Omega -S)\bar{v}_y{e_x}-2\Omega \bar{v}_x {e_y}\\ & &+ik_xB_x^0(z){\bar{b}} +\bar{b}_z\partial _zB_x^0(z){e_x}+\nu (\partial _z^2-k^2){\bar{v}},\\ \partial _t {\bar{b}}&=&S\bar{...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
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0464249241903e79972139014aa75eeb0c84292f
subsection
14
23
Numerical solution
In the following, we will assume a large-scale field similar to the oscillating Fourier mode studied in the previous section. We therefore set:B_x^0(z)=B_0\cos (k_0z).The resistive diffusion of this non-uniform field may be neglected on the timescales of interest here. To solve the equations (REF ) and (), we consider ...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.04558589681982994, 0.0284835584461689, -0.06413758546113968, -0.042046431452035904, 0.004248886369168758, -0.010442954488098621, 0.01028276327997446, 0.009336871095001698, 0.011213398538529873, 0.03432673215866089, 0.005850800313055515, 0.014508765190839767, -0.012548327445983887, 0.004...
5b4596d4df1975fd804eedb8785491238353e868
subsection
15
23
Numerical solution
In a real system, this excitation is a highly nonlinear process which depends on the small-scale properties of the turbulence.Note that these properties may depend in turn on the large-scale field and the amplitudes of the shearing waves. Therefore, our random excitation is not a precise enough turbulence model and we ...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.06185733154416084, 0.02087341621518135, -0.03524677827954292, -0.02992161549627781, 0.01420551910996437, -0.04434075206518173, 0.01571609638631344, 0.0585615299642086, 0.016921505331993103, 0.03396507725119591, -0.04473746940493584, -0.006229219492524862, 0.000013649066204379778, 0.0115...
b56a6741c8abadbe6cf79050d98fcd054ba7e9f0
subsection
16
23
Phenomenological properties
The waves described in this section are clearly inhomogeneous in the vertical direction. However, we can understand them as a version of the magnetorotational instability in the presence of a varying azimuthal field , . As one would expect, the transport coefficients \langle b_x b_y\rangle and \langle v_x v_y\rangle as...
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10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
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89ee2a6bee1aaed60d8465f4995259634a6898e5
subsection
17
23
A toy model
In this section, we provide a toy model reproducing the basic linear properties exhibited in the previous section. This toy model does not pretend to be an accurate set of closure relations for equations (REF )–() but it includes the main physical ingredients required to reproduce qualitatively the cycle behaviour desc...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1760, "openalex_id": "", "raw": "Rogachevskii, I. & Kleeorin, N. 2003, Phys. Rev. E, 68, 036301", "source_ref_id": "41ba0359ec10474f99ddfb574a8e21ab8b7b009a", "start": 1624 } ] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.02844833955168724, -0.009805825538933277, -0.028539910912513733, -0.015353556722402573, 0.015193305909633636, -0.02290823869407177, 0.01976427063345909, 0.042153600603342056, -0.012469041161239147, 0.02625061385333538, 0.015704581514000893, 0.04221465066075325, -0.020100034773349762, 0....
68f258c57ef4cd39b036d6aae9101a2e5ed3f890
subsection
18
23
A toy model
The resulting evolution of B_x and B_y is plotted in Fig. REF , where the “mean shear” curve corresponds to the first term on the right-hand side of equation (REF ), and the EMFs are the \beta and \gamma terms. When comparing with the fully nonlinear cycle (Figs REF –REF ), we find essentially the same time history for...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
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e55fd38536766a9d3d05973f9515852ce0c75517
subsection
19
23
Summary
In this paper, we have investigated the behaviour of the large-scale magnetic field in zero-net-flux simulations of the magnetorotational instability. We have first shown that the large-scale azimuthal field B_x(z) is subject to a long-timescale oscillation when the flow is turbulent. Studying the induction equation, w...
{ "cite_spans": [] }
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.04477928951382637, -0.018909864127635956, -0.022481217980384827, -0.0379723496735096, 0.00585686881095171, -0.04706862196326256, 0.020008742809295654, 0.013209433294832706, 0.020237674936652184, 0.008233956061303616, -0.019062485545873642, 0.010363033041357994, -0.013217063620686531, 0....
3535799db61982100a87fe21406a02152ea43c38
subsection
20
23
Comparison with previous works
We would like to stress that the model presented here does not constitute a full description of a sustaining mechanism for MHD turbulence in discs. Indeed, we have assumed in the linear analysis and in the closure model that the flow is able to generate continuously small-amplitude shearing waves. As mentioned previous...
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10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
[ -0.04885600507259369, -0.01841636374592781, -0.055355899035930634, -0.0048863631673157215, 0.020048966631293297, -0.018477395176887512, -0.023604072630405426, 0.03661911562085152, -0.0031374190002679825, 0.005683592054992914, -0.016371795907616615, 0.004279859364032745, -0.026548858731985092...
13cc8eba290a530132a149bf9433a109c306bcaf
subsection
21
23
Comparison with previous works
If this picture is correct, we would then expect a minimum transport of the order of a few times 10^{-3}, independently of the Reynolds numbers. Note however that this conclusion relies on the assumption that the large-scale field does not depend on the dissipation coefficients. We have shown that this assumption is pl...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 590, "openalex_id": "", "raw": "Rincon, F., Ogilvie, G. I., & Proctor, M. R. E. 2007, Physical Review Letters, 98, 254502", "source_ref_id": "39d051410933a6c360fac557fe38872040893a36", "start": 440 }, { "...
10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
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df1d08f259998abb77aaf0d9675e6dab3bc25c6f
subsection
22
23
Future work
As discussed previously, the main issue raised by our findings is how the turbulence is able to excite shearing waves. Interestingly, the same kind of problem arises in the case of the shearing box with a mean azimuthal field . Therefore, a simpler way to study this effect is to investigate the way turbulence is sustai...
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10.1051/0004-6361:200810152
0807.1703
On Self-Sustained Dynamo Cycles in Accretion Discs
[ "G. Lesur", "G. I. Ogilvie" ]
[ "astro-ph" ]
2,008
en
Physics
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58ff8b89ce8534200190105fbea17f7d7476002b
abstract
0
64
Abstract
A "Chen space" is a set X equipped with a collection of "plots" - maps from convex sets to X - satisfying three simple axioms. While an individual Chen space can be much worse than a smooth manifold, the category of all Chen spaces is much better behaved than the category of smooth manifolds. For example, any subspace ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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db42c29e4b42b0ec3ff658778fef7b3dcd93254e
subsection
1
64
Introduction
Algebraic topologists have become accustomed to working in a category of spaces for which many standard constructions have good formal properties: mapping spaces, subspaces and quotient spaces, limits and colimits, and so on. In differential geometry the situation is quite different, since the most popular category, th...
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0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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c693e0f8273e6cf8b1093c5c6628c9aac914c19b
subsection
2
64
Introduction
Despite a superficial resemblance to charts in the theory of manifolds, plots are very different: we should think of a plot in X as an arbitrary smooth map to X from a convex subset of a Euclidean space of arbitrary dimension. So instead of ensuring that Chen spaces look nice locally, plots play a different role: they ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 664, "openalex_id": "", "raw": "J. M. Souriau, Groupes differentiels, in Differential Geometrical Methods in Mathematical Physics (Proc. Conf., Aix-en-Provence/Salamanca, 1979), Lecture Notes in Math. 836, Springer, Berlin, 1980, ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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af62660aa05a4f0268602f83bf701933368cbf20
subsection
3
64
Introduction
It is nice having the solution set of an equation between smooth maps be a smooth space, but the price we pay is that a smooth space can be locally as bad as the Cantor set.So, we should not expect the theory of smooth spaces to support the wealth of fine-grained results familiar from the theory of smooth manifolds. In...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 475, "openalex_id": "", "raw": "P. Iglesias-Zemmour, Diffeology. Draft available at http://math.huji.ac.il/\\sim piz/Site/The%20Book/The%20Book.html.", "source_ref_id": "1f95f13959e02982771ad5527a35707feceafbdf", "star...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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f56f9dfd2d69c4aab017644f97fef77bbeafb222
subsection
4
64
Introduction
Our work covers a wide class of definitions that take the `maps in' approach.The structure of the paper is as follows. In Section , we define Chen spaces and diffeological spaces and give some examples. We also discuss the relation between these two formalisms, focusing on manifolds with corners and the work of Stacey ...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 321, "openalex_id": "", "raw": "A. Stacey, Comparative smootheology, available as arXiv:0802.2225.", "source_ref_id": "2f76b279ed6227e135a67d5246d5bb59e83eec75", "start": 203 } ] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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b2a2148ed00fb0bcdae4a1d777633080b425d024
subsection
5
64
Smooth Spaces
Souriau's notion of a `diffeological space' is very simple:Definition 1 An open set is an open subset of {\mathbb {R}}^n. A function f\colon U\rightarrow U^{\prime } between open sets is called smooth if it has continuous derivatives of all orders.Definition 2 A diffeological space is a set X equipped with, for each op...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 122, "openalex_id": "", "raw": "J. M. Souriau, Groupes differentiels, in Differential Geometrical Methods in Mathematical Physics (Proc. Conf., Aix-en-Provence/Salamanca, 1979), Lecture Notes in Math. 836, Springer, Berlin, 1980, ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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273ea66f3cc465b31700cacfc0210bf22d22fcad
subsection
6
64
Smooth Spaces
This marks an important realization, emphasized by Stacey : we can give a space a smooth structure without first giving it a topology. Indeed, we shall see that a smooth structure determines a topology!The notion of a smooth function f \colon C \rightarrow C^{\prime } between convex sets is a bit subtle, particularly f...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 134, "openalex_id": "", "raw": "A. Stacey, Comparative smootheology, available as arXiv:0802.2225.", "source_ref_id": "2f76b279ed6227e135a67d5246d5bb59e83eec75", "start": 0 } ] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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4b28ffa1c91aead15745ce7ceb0527327c293e83
subsection
7
64
Smooth Spaces
If \gamma \colon {\mathbb {R}}\rightarrow C is a smooth curve in C, then f \gamma is a smooth curve in C^{\prime }.The equivalence of conditions 1 and 2 is not hard; the equivalence of 2 and 3 was proved by Kriegl , and appears as Theorem 24.5 in Kriegl and Michor's book .Since most of our results apply both to Chen sp...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 274, "openalex_id": "", "raw": "A. Kriegl, Remarks on germs in infinite dimensions, Acta Math. Univ. Comenianae 66 (1997), 1–18.", "source_ref_id": "79a0cf8fd0bdc4347a149134ca898e19ae5259b5", "start": 116 }, { ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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2096ba5132d903aacbce6d22b70e771067ac4d88
subsection
8
64
Examples
Next we give some examples. For these it is handy to call the set of plots in a smooth space its smooth structure. So, we may speak of taking a set and putting a smooth structure on it to obtain a smooth space.Any domain D becomes a smooth space, where the plots \varphi \colon D^{\prime } \rightarrow D are just the smo...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1150, "openalex_id": "", "raw": "P. Iglesias-Zemmour, Diffeology. Draft available at http://math.huji.ac.il/\\sim piz/Site/The%20Book/The%20Book.html.", "source_ref_id": "1f95f13959e02982771ad5527a35707feceafbdf", "sta...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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21c1d5c87d236bc446685c18581e2c388ea762f1
subsection
9
64
Comparison
We should also say a bit about how Chen spaces and diffeological spaces differ, and how they are related. To begin with, let us compare their treatment of manifolds with boundary, or more generally manifolds with corners , .An n-dimensional manifold with corners M has charts of the form \varphi \colon X_k \rightarrow M...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 224, "openalex_id": "", "raw": "K. Jänich, On the classification of O(n)-manifolds, Math. Ann. 176 (1968), 53–76.", "source_ref_id": "a8577447eaf5f2f85e69a38671a1cd5bbb20054f", "start": 106 }, { "arxiv_id...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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aef7e2766180858995d5b4ed7fbf615488c88f07
subsection
10
64
Comparison
These take advantage of the fact that every open subset of \mathbb {R}^n becomes a Chen space with its subspace smooth structure, and conversely, every convex subset of \mathbb {R}^n becomes a diffeological space.Using this, Stacey defines for any Chen space X a diffeological space {\rm So}X with the same underlying se...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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8dc8aec7185770285df5853fbb4f61c0969dd47b
subsection
11
64
Comparison
To see this, he takes I to be [0,1] \subset {\mathbb {R}} made into a Chen space with its subspace smooth structure. If I were isomorphic to a Chen space in the image of {\rm Ch}^\flat , say I \cong {\rm Ch}^\flat X, we would then have {\rm Ch}^\flat {\rm So}I = {\rm Ch}^\flat {\rm So}{\rm Ch}^\flat X = {\rm Ch}^\flat ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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a3b3b2d9f27393eb2e5c8858d1b2e09eacbfd3c3
subsection
12
64
Convenient Properties of Smooth Spaces
Now we present some useful properties shared by Chen spaces and diffeological spaces. Following Def. REF , we call either kind of space a `smooth space', and we use \mathcal {C} ^\infty to denote either the category of Chen spaces or the category of diffeological spaces. Most of the proofs are straightforward diagram c...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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de7b04d77a99cc067e49d9a2a1e9bcd28d68b8da
subsection
13
64
Convenient Properties of Smooth Spaces
Not every epimorphism is of this form: for example, the natural map from {\mathbb {R}} with its standard smooth structure to {\mathbb {R}} with its indiscrete smooth structure is also an epimorphism. In Prop. REF , we show that a smooth map p \colon X \rightarrow Y comes from taking a quotient space precisely when p is...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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4c283622316d9aeb5c2c9974b072d65b5e4bf33e
subsection
14
64
Convenient Properties of Smooth Spaces
Moreover, for any other smooth space Q with smooth maps f_X \colon X \rightarrow Q and f_Y \colon Y \rightarrow Q, there exists a unique smooth maps f \colon X + Y \rightarrow Q such that { & Q & \\ X[r]_{i_X}[ur]^{f_X} & X + Y[u]_{f} & Y[l]^{i_Y}[ul]_{f_Y}\\ } commutes. So, X+Y is indeed the coproduct of X and Y in ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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853f032d84aa1d3fbedea89467afda304890dfb6
subsection
15
64
Convenient Properties of Smooth Spaces
The natural functions p_X \colon X \times _Z Y \rightarrow X, \qquad p_Y \colon X \times _Z Y \rightarrow Y are then smooth, and it is easy to check this diagram is a pullback square: { X \times _Z Y [d]_{p_Y} [r]^{p_X} & X[d]^f \\ Y[r]_g & Z \\ } In other words, given any commutative square of smooth maps like thi...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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ba92805891df8357f473d2422d9ecad99647a813
subsection
16
64
Convenient Properties of Smooth Spaces
Mapping spaces Given smooth spaces X and Y, the set \mathcal {C} ^\infty (X,Y) =\lbrace f\colon X\rightarrow Y\colon f\text{ is smooth}\rbrace becomes a smooth space where a function \tilde{\varphi } \colon D\rightarrow \mathcal {C} ^\infty (X,Y) is a plot if and only if the corresponding function \varphi \colon D \t...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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82233aaa4f12e8e9c4b76610b0cd55222efef329
subsection
17
64
Convenient Properties of Smooth Spaces
This allows us to define the smooth structure on \mathcal {C} ^\infty _B(Y,Z): for any domain D, a function \tilde{\varphi } \colon D \rightarrow C_B^\infty (Y,Z) is a plot if and only if p \tilde{\varphi } is smooth and the corresponding function \varphi \colon D \times _B Y \rightarrow Z is smooth. With this smoo...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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6bb043d27be41a98153d7617abda0c89259f4386
subsection
18
64
Smooth Spaces as Generalized Spaces
The concept of a `generalized space' was developed in the context of quasitopos theory by Antoine , Penon , and Dubuc , . Generalized spaces form a natural framework for studying Chen spaces, diffeological spaces, and even simplicial complexes. For us, a category of generalized spaces will be a category of `concrete sh...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 122, "openalex_id": "", "raw": "P. Antoine, Etude élémentaire des catégories d'ensembles structurés, Bull. Soc. Math. Belgique, 18 (1966), 142–164, 387–414.", "source_ref_id": "2cd3854a9b285706e4684ea7bb17f7cf79c93c54", ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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6a3428e969d19eee076e6fdf1457e0f9425df576
subsection
19
64
Smooth Spaces as Generalized Spaces
Axiom 1 in the definition of a Chen space is what gives us a contravariant functor from {\sf Chen} to {\rm Set}: it says that given any morphism f \colon C \rightarrow D in {\sf Chen}, we get a functionX(f) \colon X(D) \rightarrow X(C)sending any plot \varphi \colon D \rightarrow X to the plot \varphi f \colon C \right...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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af8a5eae6fc62f747e33bb8f532c247bf6fc285a
subsection
20
64
Smooth Spaces as Generalized Spaces
\end{}Quite generally, any object D in a category with a terminal object has an underlying set hom(1,D), often called its set of `points^{\prime }. The requirement that hom(1,-) be faithful says that two morphisms f,g C D in are equal when they induce the same functions from points of C to points of D. In other words: ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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417191e50b8a0dea1b7fb5341b2ec0307c3476ab
subsection
21
64
Smooth Spaces as Generalized Spaces
The category {\sf Chen} has a subcanonical coverage where (i_j\colon C_j\rightarrow C|j\in J) is a covering family if and only if the convex sets C_j \subseteq C form an open covering of the convex set C \subseteq {\mathbb {R}}^n with its usual subspace topology, and i_j \colon C_j \rightarrow C are the inclusions.Give...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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feee3ee7163f8dc98480a06fc0d8df39c8ec30ea
subsection
22
64
Smooth Spaces as Generalized Spaces
Then, let \varphi \in {\mathbf {X}}(C) and compute \underline{\varphi } \colon {\rm hom}(1,C) \rightarrow X(1) \cong X:\underline{\varphi }(c) = X(c)(\varphi ) = \varphi (c)where at the last step we identify the smooth function c \in {\rm hom}(1,C) with the one point in its image. So, \underline{\varphi } is the underl...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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b24d87d2f1d4cdc96350559685670ac26c1fe28d
subsection
23
64
Smooth Spaces as Generalized Spaces
When we turn a concrete sheaf {\mathbf {X}} into a Chen space X and back into a concrete sheaf {\mathbf {X}}^{\prime }, we have{\mathbf {X}}^{\prime }(C) = \lbrace \underline{\varphi } \colon C \rightarrow X(1) \rbracebut the latter is naturally isomorphic to X(C) via the function\begin{array}{rcl} X(C) &\rightarrow & ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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4a34b4ee58316875753f69016bfd827ae5076120
subsection
24
64
Smooth Spaces as Generalized Spaces
For instance, take f_i to be the identity function on D. The coverage is clearly subcanonical since each covering includes the identity morphism.Henceforth we make {\sf F} into a concrete site with the above coverage. Since every covering family contains the identity, this coverage is `vacuous': every presheaf is a she...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 494, "openalex_id": "", "raw": "M. Grandis, Finite sets and symmetric simplicial sets, Th. Appl. Cat. bf 8 (2001), 244–252. Available at http://www.tac.mta.ca/tac/volumes/8/n8/8-08abs.html.", "source_ref_id": "c5455f959b658a...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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fe0999502bd0e19054b5f4fa5e29456e055a7b0b
subsection
25
64
Smooth Spaces as Generalized Spaces
Since a map {\mathbf {X}}\Rightarrow {\mathbf {Y}} of {\sf F} spaces is completely determined by the function 1\colon {\mathbf {X}}(1)\rightarrow {\mathbf {Y}}(1) it is clear that this functor is faithful. We see that the functor is full since given a map of simplicial complexes f\colon (X,K)\rightarrow (Y,L) and a mor...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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4a90cd253558efe1cfc4795fad9d3ec0ac922d17
subsection
26
64
Convenient Properties of Generalized Spaces
In this section we establish convenient properties of any category of generalized spaces. We begin with some handy notation. In Section we introduced three closely linked notions of `underlying set' or `underlying function' in the context of a concrete site . It will now be convenient, and we hope not confusing, to de...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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2e963887528018ace1ca994619685cd7c9407ebf
subsection
27
64
Convenient Properties of Generalized Spaces
Recall that f and g are natural transformations between the functors X,Y opSet, so given D the following squares commute for each d\in \underline{D}:{ X(D)[r]^{f_D}[d]_{X(d)} & Y(D)[d]^{Y(d)} & & X(D)[r]^{g_D}[d]_{X(d)} & Y(D)[d]^{Y(d)} \\ X(1)=\underline{X}[r]_{\underline{f}} & \underline{Y}=Y(1) & & X(1)=\underline{X...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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15bca24e02ddfaed9c8dc2ec86b91be4617258ea
subsection
28
64
Convenient Properties of Generalized Spaces
Henceforth we denote this functor by an underline: \underline{\;\;} \colon {\rm Set}. So, any domain D has an underlying set \underline{D}, and any morphism f \colon C \rightarrow D in has an underlying function f C D. The concreteness condition on says that this underlying set functor is faithful. The underlying se...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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064bd90e75e09ac1a7e54447a8a8e014e70a039a
subsection
29
64
Convenient Properties of Generalized Spaces
Since the natural transformation\underline{\;\;} \colon Y(D) \rightarrow \underline{Y}^{\underline{D}}is one-to-one, it suffices to show that\underline{f_D(\varphi )}(d) = \underline{g_D(\varphi )}(d)for all d\in D, or in other words,Y(d) f_D(\varphi ) = Y(d) g_D(\varphi ) .By the above commuting squares, this amounts ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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2907a6f474c79ddd9e35ce858f13cca79d47d507
subsection
30
64
Subspaces, Quotient Spaces, and Limits
With these preliminaries in hand, we now study subspaces and quotient spaces of spaces, and show that the category of spaces has a weak subobject classifier, \Omega . In the process we will show that has limits.For Chen spaces or diffeological spaces, \Omega is just the 2-element set 2 = \lbrace 0,1\rbrace equipped w...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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c1b63f31929b571ac3f7524b9334a4a0f449449e
subsection
31
64
Subspaces, Quotient Spaces, and Limits
Finally, since plots \varphi \in \Omega (D) are in one-to-one correspondence with functions \underline{\varphi } \colon \underline{D} \rightarrow 2, the sheaf \Omega is concrete.Proposition 31 A monomorphism (resp. epimorphism) in is a map f\colon X\rightarrow Y for which the underlying function \underline{f} is injec...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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e37bab10938c275baa6005a1871385b8b4e74153
subsection
32
64
Subspaces, Quotient Spaces, and Limits
Note that for any plot \varphi \in B(D), the plot g_D(\varphi ) \in X(D) has\underline{g_D (\varphi )}(\underline{D}) = \underline{g} \underline{\varphi } (\underline{D}) \subseteq \underline{i}(\underline{A}) ,where in the first step we use the naturality of the map sending a plot to its underlying function, and in th...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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deacafdd1bc395b482d8dfe2f82f62c965f2a4fe
subsection
33
64
Subspaces, Quotient Spaces, and Limits
Since A' is a subspace of X and (D)=A', there exists a unique plot A'(D) such that jD()=. Thus we have tD()A(D) and by commutativity of the diagram iDtD()=jD()=. For any other 'A(D) with iD(')=, we have '=tD() since i is a monomorphism, and thus tD() is unique as desired.Definition 35 In any category, an epimorphism p...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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c1286d4c5b542600c4d9b2449935e18c1b66fd89
subsection
34
64
Subspaces, Quotient Spaces, and Limits
To show that \underline{t} induces a map of spaces, we need to check that the following naturality square commutes for every map d D' D in :{ B(D) [r]^{t_D}@{-> >}[d]_{B(d)} & A(D) @{ >->}[d]^{A(d)}\\ B(D^{\prime }) [r]_{t_{D^{\prime }}} & A(D^{\prime })\\ }Since B and A are concrete sheaves, we can check that this dia...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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e2e3d37312579ae8935eb51643ab32bcf157d72a
subsection
35
64
Subspaces, Quotient Spaces, and Limits
Either \varphi came from a plot in E(D), in which case we consider the covering family with just the identity map (1 \colon D \rightarrow D), and there exists a plot \hat{\varphi }\in E(D) which maps to \varphi , or \varphi arose from sheafification. In the latter case, there exists a family (f_i \colon D_i \rightarrow...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1427, "openalex_id": "", "raw": "S. Mac Lane and I. Moerdijk, Sheaves in Geometry and Logic: A First Introduction to Topos Theory, Springer, Berlin, 1992.", "source_ref_id": "b8026f5bc4c6627f9a2d7b94052bd2f2dc9153df", ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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9d3de5f3b5351e72a67df912e1c2287a2563ea9b
subsection
36
64
Subspaces, Quotient Spaces, and Limits
So, taking the limits of both diagrams, we get a one-to-one function\lim _{\alpha \in C} \, F(\alpha )(D) \rightarrow \lim _{\alpha \in C} \, \underline{F(\alpha )}^{\underline{D}}which by the properties of limits can be reinterpreted as a one-to-one function\lim _{\alpha \in C} \, F(\alpha )(D) \rightarrow (\lim _{\al...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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ada572b020c5ab08fd015f7ef5135befb34ec075
subsection
37
64
Subspaces, Quotient Spaces, and Limits
So, (D) will be the power set of D:Proposition 30 There is a space such that for any object D , \Omega (D) = 2^{\underline{D}}, and for any morphism f \colon C \rightarrow D in , (f) 2D 2C sends any plot D 2 to the plot f C 2.\Omega is clearly a presheaf. To show that it is a sheaf, we suppose (f_i \colon D_i \rightar...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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2d90d17bc960bec9dd9dbc92635b87853fb0ac72
subsection
38
64
Subspaces, Quotient Spaces, and Limits
Then the map from {\rm hom}(1,X) to {\rm hom}(1,Y) given by composing with f is injective, but this says precisely that \underline{f} is injective.Next, suppose f is epic. Then the map from {\rm hom}(Y,\Omega ) to {\rm hom}(X,\Omega ) given by composing with f is injective, but this says that the map from 2^{\underline...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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57e2c250b212c955242dee607492ec0117f012f9
subsection
39
64
Subspaces, Quotient Spaces, and Limits
We sett_D(\varphi ) = \psi .We can check that t is a natural transformation by considering a morphism f\colon D^{\prime }\rightarrow D in and the following diagram:{ &&& \underline{A}@{>->}[d]^{\underline{i}}\\ \underline{D^{\prime }}@{-->}[urrr][r]_{\underline{f}} & \underline{D}[r]_{\underline{\varphi }}@{-->}[urr]|-...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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212c00880350223b26ecc113e62d60aa9488f0ba
subsection
40
64
Subspaces, Quotient Spaces, and Limits
For any other 'A(D) with iD(')=, we have '=tD() since i is a monomorphism, and thus tD() is unique as desired.Definition 35 In any category, an epimorphism p\colon E\rightarrow B is strong if given any monomorphism i\colon A\rightarrow X and morphisms f,g making the outer square here commute:{ E [r]^{f}@{-> >}[d]_{p} ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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35ce16cba8dd11f5c26f701fb91b674d67e1743a
subsection
41
64
Subspaces, Quotient Spaces, and Limits
To show that \underline{t} induces a map of spaces, we need to check that the following naturality square commutes for every map d D' D in :{ B(D) [r]^{t_D}@{-> >}[d]_{B(d)} & A(D) @{ >->}[d]^{A(d)}\\ B(D^{\prime }) [r]_{t_{D^{\prime }}} & A(D^{\prime })\\ }Since B and A are concrete sheaves, we can check that this dia...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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9f4656764aab843475efa5cd86ee86bc53b88532
subsection
42
64
Subspaces, Quotient Spaces, and Limits
Either \varphi came from a plot in E(D), in which case we consider the covering family with just the identity map (1 \colon D \rightarrow D), and there exists a plot \hat{\varphi }\in E(D) which maps to \varphi , or \varphi arose from sheafification. In the latter case, there exists a family (f_i \colon D_i \rightarrow...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1427, "openalex_id": "", "raw": "S. Mac Lane and I. Moerdijk, Sheaves in Geometry and Logic: A First Introduction to Topos Theory, Springer, Berlin, 1992.", "source_ref_id": "b8026f5bc4c6627f9a2d7b94052bd2f2dc9153df", ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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ead758b05aef4e1178851315423e2981c9aa860a
subsection
43
64
Subspaces, Quotient Spaces, and Limits
So, taking the limits of both diagrams, we get a one-to-one function\lim _{\alpha \in C} \, F(\alpha )(D) \rightarrow \lim _{\alpha \in C} \, \underline{F(\alpha )}^{\underline{D}}which by the properties of limits can be reinterpreted as a one-to-one function\lim _{\alpha \in C} \, F(\alpha )(D) \rightarrow (\lim _{\al...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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aad27fec1d8767fedc611566d8309eafc622aeb7
subsection
44
64
Parametrized Mapping Spaces
We next turn to the existence of parametrized mapping spaces between spaces over a fixed base B.Definition 41 Given an object B in a category \mathcal {C} , the category of objects over B (sometimes called the slice category of B), has morphisms f\colon E\rightarrow B in \mathcal {C} as objects and commuting triangle...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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caeac2191073a9041dfbe4b1464812abb49021e5
subsection
45
64
Parametrized Mapping Spaces
Alternatively, the space structure on XB Y can be quickly obtained by the following lemma:Lemma 44 The monomorphism m\colon X\times _A Y\rightarrow X\times Y in given by inclusion of sets \underline{X\times _A Y}\hookrightarrow \underline{X\times Y} is a strong monomorphism.Given C\in , then for any (XY)(C) such that (...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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d4e32c432ddedab74b592ffb8be1dc83e0177527
subsection
46
64
Parametrized Mapping Spaces
We say that \underline{\varphi } determines a plot for \mathcal {D} _B(X,Y) if this composite function q\underline{\varphi } underlies a map of spaces and \underline{C}\times _{\underline{B}} \underline{X}\stackrel{\underline{\varphi }\times _{\underline{B}} 1}{\longrightarrow }\coprod _{b\in \underline{B}} \underline...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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d474205e0363e7ed40a4ff61ec903a76d9c030f6
subsection
47
64
Parametrized Mapping Spaces
We consider the following diagram for each j \in J:{ D_j [r]^{g_j} [drr]_{\tau _{ij}} & C^{\prime } [r]^{\psi } & C \times _B X [r]^<<<<<{\varphi \times _B 1} & \mathcal {D} _B(X,Y) \times _B X [r]^>>>>>>{{\rm ev}} & Y \\ & & C_i \times _B X [ur]_{\varphi _i \times _B 1} & & }It is easy to check that this diagram commu...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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3cce0cd2c0302ed505ba2ff8b9e24bf2641c2675
subsection
48
64
Parametrized Mapping Spaces
The equality of the first components follows from \underline{f_i h_{ij}}(e_j) = \underline{f_l h_{lk}}(e_k), and that the family of plots \lbrace \varphi _i \in \mathcal {D} _B(X,Y)(C_i) | i \in I \rbrace is compatible. Since Y is a smooth space, we have by the sheaf condition that {\rm ev}(\varphi \times _B 1_X)\psi i...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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79af5fd0adafaced69d69f37f43973cdef5040e1
subsection
49
64
Parametrized Mapping Spaces
One can check that the following diagram commutes and it follows that f determines a map: (-40,0)*{\underline{C}\times _{\underline{B}} \underline{X}}="1"; (-15,0)*{\underline{Z}\times _{\underline{B}} \underline{X}}="2"; (15,0)*{\coprod \underline{\mathcal {D}}(X_b,Y_b)\times _{\underline{B}} \underline{X}}="3"; (...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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727423837467c86bd4c1fe013ad6fc2059f36473
subsection
50
64
Parametrized Mapping Spaces
This induces a map Z^{\prime }\times _B X to Z\times _B X which we compose with \tilde{f} to obtain the desired map. It follows that (z^{\prime },x)\in Z^{\prime }\times _B X\mapsto (g(z^{\prime }),x)\in Z\times _B X\mapsto \tilde{f}(g(z^{\prime }),x)\in Y. Thus the diagram commutes. Given a map h\colon Y \rightarrow Y...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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f0a6afab9847709d176226e93ef8d87b355ee6f7
subsection
51
64
Parametrized Mapping Spaces
Given objects X,Y over B, we call the internal hom \mathcal {C} _B(X,Y) a parametrized mapping space.We want to show that the category of spaces is locally cartesian closed. To do this we need to determine the product and internal hom in the category of spaces over some space B. Given two spaces over B, { X[dr]_{p_X} ...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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b7f308dce347759b8ead0bac5fd5f18ddcb98b89
subsection
52
64
Parametrized Mapping Spaces
We say that \underline{\varphi } determines a plot for \mathcal {D} _B(X,Y) if this composite function q\underline{\varphi } underlies a map of spaces and \underline{C}\times _{\underline{B}} \underline{X}\stackrel{\underline{\varphi }\times _{\underline{B}} 1}{\longrightarrow }\coprod _{b\in \underline{B}} \underline...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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82df8e38153b3fa7153b2a4c0262cfdd2caeba0c
subsection
53
64
Parametrized Mapping Spaces
We consider the following diagram for each j \in J:{ D_j [r]^{g_j} [drr]_{\tau _{ij}} & C^{\prime } [r]^{\psi } & C \times _B X [r]^<<<<<{\varphi \times _B 1} & \mathcal {D} _B(X,Y) \times _B X [r]^>>>>>>{{\rm ev}} & Y \\ & & C_i \times _B X [ur]_{\varphi _i \times _B 1} & & }It is easy to check that this diagram commu...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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ff5f94621fe37d355da790f311a574dbd00b9df6
subsection
54
64
Parametrized Mapping Spaces
The equality of the first components follows from \underline{f_i h_{ij}}(e_j) = \underline{f_l h_{lk}}(e_k), and that the family of plots \lbrace \varphi _i \in \mathcal {D} _B(X,Y)(C_i) | i \in I \rbrace is compatible. Since Y is a smooth space, we have by the sheaf condition that {\rm ev}(\varphi \times _B 1_X)\psi i...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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312f3698681800bf67a1bc594ad9aea3a16b496b
subsection
55
64
Parametrized Mapping Spaces
One can check that the following diagram commutes and it follows that f determines a map: (-40,0)*{\underline{C}\times _{\underline{B}} \underline{X}}="1"; (-15,0)*{\underline{Z}\times _{\underline{B}} \underline{X}}="2"; (15,0)*{\coprod \underline{\mathcal {D}}(X_b,Y_b)\times _{\underline{B}} \underline{X}}="3"; (...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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69203da627fc94ae3d254d12b836f9b940b506cd
subsection
56
64
Parametrized Mapping Spaces
This induces a map Z^{\prime }\times _B X to Z\times _B X which we compose with \tilde{f} to obtain the desired map. It follows that (z^{\prime },x)\in Z^{\prime }\times _B X\mapsto (g(z^{\prime }),x)\in Z\times _B X\mapsto \tilde{f}(g(z^{\prime }),x)\in Y. Thus the diagram commutes. Given a map h\colon Y \rightarrow Y...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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1384fee5db932d55419245ed69b9d6eb9317e693
subsection
57
64
Colimits
In Prop. REF we showed that the category of spaces has limits, which can be computed pointwise. To compute colimits in , we need some facts about `sheafification^{\prime } and also `concretization^{\prime }. Given any site , sheafification is a functor that takes presheaves on to sheaves on , but does not affect preshe...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 987, "openalex_id": "", "raw": "S. Mac Lane and I. Moerdijk, Sheaves in Geometry and Logic: A First Introduction to Topos Theory, Springer, Berlin, 1992.", "source_ref_id": "b8026f5bc4c6627f9a2d7b94052bd2f2dc9153df", "...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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96435034d7a5d1eaf664475d8afa750ed5203df5
subsection
58
64
Colimits
On the other hand, there is an obvious inclusion functor R\colon \mathrm {Conc}({\rm Set}^{{\rm op}}) \rightarrow {\rm Set}^{{\rm op}} .Lemma 47 L is left adjoint to R.Given a presheaf X, a concrete presheaf Y and a natural transformation f\colon L(X)\rightarrow Y, we obtain a natural transformation \tilde{f}\colon X...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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1a8bcaa262e49d41a40fe093390ac9ae8f0e3b51
subsection
59
64
Colimits
This function takes a compatible family \lbrace \varphi _i \rbrace to the compatible family \lbrace \varphi _{j} \rbrace \subseteq \lbrace \varphi _i \rbrace for R^{\prime }.Since the sheafification process is pointwise a colimit of sets, given plots \varphi ,\varphi ^{\prime } \in X^+(D) with the same underlying funct...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 1698, "openalex_id": "", "raw": "S. Mac Lane and I. Moerdijk, Sheaves in Geometry and Logic: A First Introduction to Topos Theory, Springer, Berlin, 1992.", "source_ref_id": "b8026f5bc4c6627f9a2d7b94052bd2f2dc9153df", ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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6a83806ecb70bda1f7e1794cedd361ca4aeff75e
subsection
60
64
Colimits
Chen described a systematic process for improving any predifferentiable space to a Chen space. This process is just the plus construction! The point is that by Lemma REF , we can turn a concrete presheaf into a concrete sheaf using the plus construction.The following result is an easy spinoff of what we have done:Propo...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 460, "openalex_id": "", "raw": "S. Mac Lane and I. Moerdijk, Sheaves in Geometry and Logic: A First Introduction to Topos Theory, Springer, Berlin, 1992.", "source_ref_id": "b8026f5bc4c6627f9a2d7b94052bd2f2dc9153df", "...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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bcfa47dffad4b77a45f577d7987d9e94946fd589
subsection
61
64
Colimits
So, if X is a presheaf, X++ is a sheaf --- and in fact it is the sheafification of X. Next we turn to concretization, which makes presheaves `concrete':Definition 46 Given a concrete site , we say a presheaf X opSet is {\bf concrete} if for every object D , the function sending plots \varphi \in X(D) to functions \unde...
{ "cite_spans": [] }
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
en
Mathematics
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4c4cf1f5c9dca16f228ca2ba0854ddce3fc67a0c
subsection
62
64
Colimits
Naturality in the second argument follows similarly.Lemma 48 Any concrete presheaf on a concrete site is a separated presheaf.Clear.It follows that for any concrete presheaf, sheafification is the same as one application of Grothendieck's plus construction. This brings us to the following lemma:Lemma 49 Given a concre...
{ "cite_spans": [ { "arxiv_id": "", "doi": "", "end": 2607, "openalex_id": "", "raw": "S. Mac Lane and I. Moerdijk, Sheaves in Geometry and Logic: A First Introduction to Topos Theory, Springer, Berlin, 1992.", "source_ref_id": "b8026f5bc4c6627f9a2d7b94052bd2f2dc9153df", ...
0807.1704
Convenient Categories of Smooth Spaces
[ "John C. Baez", "Alexander E. Hoffnung" ]
[ "math.DG", "math.CT" ]
2,008
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Mathematics
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