I A glitch in Jorrie’s Cosmo-Calculator?

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  • Thread starter Thread starter JimJCW
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AI Thread Summary
Jorrie’s Cosmo-Calculator is experiencing persistent inconsistencies in results for Dnow and Dthen compared to Gnedin’s and Wright’s calculators, particularly at low redshift values. Users speculate there may be a glitch, possibly linked to numerical integration methods used in the calculator. Adjustments to the integration parameters have shown some reduction in error but not a complete fix, indicating deeper issues in the implementation. The calculator was originally designed as an educational tool, which may explain some of its limitations. Ongoing investigations are needed to address these discrepancies and improve accuracy.
  • #151
Let’s summarize the situation:

(1) The glitch associated with Dnow(z) discussed in Post #1 is eliminated in LightCone8 (see Post #102).

(2) The error associated with Ω’s in Jorrie’s calculator discussed in Post #109 is fixed in LightCone8 (see Post #148).

(3) The difference in calculated Dnow(z) using LightCone8 and ICRAR still needs to be resolved (see Post #102). I believe I can do that, but first, I need @pbuk and @Jorrie to change the following conversion,

1 pc = 3.262 ly​

in LightCone8 to,

1 pc = 3.261563777 ly​

This will make direct comparison of results from the two calculators possible.
 
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  • #152
JimJCW said:
(3) The difference in calculated Dnow(z) using LightCone8 and ICRAR still needs to be resolved (see Post #102). I believe I can do that, but first, I need @pbuk and @Jorrie to change the following conversion,

1 pc = 3.262 ly​

in LightCone8 to,

1 pc = 3.261563777 ly​

This will make direct comparison of results from the two calculators possible.
This could surely improve accuracy for comparison purposes, but take note that Lightcone8 does not allow ##\Omega_r## to be identically zero, but only a minimum value through setting ##z_{eq} = 999999##.

(This with reference to your Post #102, where you compared calculators for ##\Omega_r = 0##)

At low redshift a tiny radiation density makes negligible difference, but not so for high redshift work.
 
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  • #153
Jorrie said:
This could surely improve accuracy for comparison purposes, . . .

My goal is to be able to say,

Calculation results from Lightcone8 and ICRAR are consistent.​

This is true for the following quantities,

LightCone8
ICRAR
z0.020.02
Scale (a)9.803921569E-019.803921569E-01
H(z)6.837765717E+016.837765717E+01
OmegaM3.217304253E-013.217304253E-01
OmegaL6.781722253E-016.781722253E-01
OmegaR9.734946123E-059.734946125E-05
OmegaT1.000000000E+001.000000000E+00

but not for Dnow and Dthen:

LightCone8ICRAR
z0.020.02
T Gyr1.351246087E+011.351276116E+01
Dnow Gpc8.808897954E-028.810076113E+01
Dthen Gpc8.636174465E-028.637329523E+01
rho kg/m38.782193743E-278.782799071E-27

I believe changing the conversion to ‘1 pc = 3.261563777 ly’ in LightCone8 will resolve this discrepancy.
@pbuk
 
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