Static universe - revisited

In article ,
Eric Flesch writes:
The *integrated* luminosity is modelled as constant, but the peak
luminosity inversely varies with the width of the light curve,

Isn't this backwards? I thought the slow light curves (large
"stretch") have the largest peak luminosities. See Fig 16 of
Takanishi et al. (2008) for example:
http://adsabs.harvard.edu/abs/2008MNRAS.389.1577T
(Note they plot inverse stretch, i.e. small values on the abscissa
indicate slow light curves.)

at high z, we see SN1a with lower peak luminosity and
broader light curves (after FRW-modifying the raw data).

Reference? If I've got the sign right, I'd expect broader light
curves and higher peak luminosity.

I don't, though, understand a different poster's reference to "mag
45" objects.

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On Apr 26, 1:30*am, Steve Willner wrote:
[...]

I don't, though, understand a different poster's reference to "mag
45" objects.

http://supernova.lbl.gov/Union/figur...n2_mu_vs_z.txt

Columns: Identification, redshift, apparent magnitude, uncertainty in
magnitude.

2003aj 1.307 45.1191615825 0.265400797402

I only brought it up to highlight that the small sample size at high
redshifts is due to the low visibility of the objects.


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In article ,
Eric Gisse wrote:
On Apr 26, 1:30*am, Steve Willner wrote:
[...]

I don't, though, understand a different poster's reference to "mag
45" objects.

http://supernova.lbl.gov/Union/figur...n2_mu_vs_z.txt

Columns: Identification, redshift, apparent magnitude, uncertainty in
magnitude.

But their 'apparent magnitude' doesn't seem to be anything like the
actual apparent magnitude that you observe with a telescope ... if I
ask http://stella.sai.msu.su:8080/~pavlyuk/snlcurve/ for the light
curve of 1993ah, I get something that's declining from 17.2, where the
figure in http://supernova.lbl.gov/Union/figur...n2_mu_vs_z.txt
for 1993ah is 35.3. I imagine the 'M(h=0.7, statistical only) figure
at the top of the file is a correction from their magnitude figure to
the actually-observed one.

(similarly, 1996BO peaks around magnitude 16 and is described as
33.something in the datafile)

Tom

In article ,
Eric Gisse writes:
http://supernova.lbl.gov/Union/figur...n2_mu_vs_z.txt

Columns: Identification, redshift, apparent magnitude, uncertainty in
magnitude.

2003aj 1.307 45.1191615825 0.265400797402

The last two numbers are the distance modulus (in magnitudes) and its
uncertainty. Apparent magnitude 45 would be about 20 magnitudes too
faint to detect. I agree this is not as clear as it might be, but
the file name gives a good clue. (Mu is the usual symbol for
distance modulus.) Or you can find it in the description file
http://supernova.lbl.gov/Union/descriptions.html
The number of significant digits is, of course, ridiculous.

The B magnitude 26.07 is given in
http://supernova.lbl.gov/Union/figur...on2_AllSNe.tex
I'm not sure what kind of magnitude it's supposed to be, but my guess
would be the observed peak magnitude. No doubt the published paper
explains.

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On Apr 26, 9:50*am, Steve Willner wrote:
In article ,
*Eric Gisse writes:

http://supernova.lbl.gov/Union/figur...n2_mu_vs_z.txt

Columns: Identification, redshift, apparent magnitude, uncertainty in
magnitude.

2003aj 1.307 45.1191615825 0.265400797402

The last two numbers are the distance modulus (in magnitudes) and its
uncertainty. Apparent magnitude 45 would be about 20 magnitudes too
faint to detect. I agree this is not as clear as it might be, but
the file name gives a good clue. (Mu is the usual symbol for
distance modulus.) Or you can find it in the description filehttp://supernova.lbl.gov/Union/descriptions.html
The number of significant digits is, of course, ridiculous.

Ack, I thought that was apparent magnitude.

Thanks. The site has a LOT of data, but is not nearly as easy to read
as it could be.


The B magnitude 26.07 is given inhttp://supernova.lbl.gov/Union/figures/SCPUnion2_AllSNe.tex
I'm not sure what kind of magnitude it's supposed to be, but my guess
would be the observed peak magnitude. No doubt the published paper
explains.

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On Tue, 26 Apr 11, Steve Willner wrote:
Eric Flesch writes:
The *integrated* luminosity is modelled as constant, but the peak
luminosity inversely varies with the width of the light curve,

Isn't this backwards? I thought the slow light curves (large
"stretch") have the largest peak luminosities. See Fig 16 of
Takanishi et al. (2008) for example:
http://adsabs.harvard.edu/abs/2008MNRAS.389.1577T

Yes, apologies, my point was about the Malmquist problem but I fumbled
the luminosity-stretch relation -- been a few years since I played
around with this. Gisse put me off with his comment about all SN1a
luminosities being the same, which is of course wrong.

at high z, we see SN1a with lower peak luminosity and
broader light curves (after FRW-modifying the raw data).

Reference? If I've got the sign right, I'd expect broader light
curves and higher peak luminosity.

As would I, but the peak luminosity is lower at high z, at least
whenever they present it. An old paper describing the Malmquist
problem was 2001 ARA&A,39,67 in which Bruno Leibundgut wrote "A
striking discrepancy is that none of the slowly declining and, hence,
very luminous objects observed in the nearby sample have been
discovered at large distances. ... This is clearly contrary to what is
expected from a Malmquist bias ...". An interesting sidelight was
that the high-z SN did have bluer colors, as expected -- the reason
it's interesting is because this has since been stood on its head in
that nowadays the Union high-z SNe are *redder* than expected (see
2010 ApJ,716,712, page 2, 2nd column), so the problem has gotten
worse, not better.

I did see a recent chart of peak luminosity x redshift which showed
that the problem continues to this day, but can't find it now, grrr.

I've searched recent SNIa papers for Malmquist, but the topic seems to
have dropped off the radar. Surely this should be a primary
consideration, especially for objects like high-z SNIa for which we
need the full light curve to compute its intrinsic peak luminosity.

Eric Flesch

Reference? If I've got the sign right, I'd expect broader light
curves and higher peak luminosity.

In article ,
Eric Flesch writes:
As would I, but the peak luminosity is lower at high z, at least
whenever they present it. An old paper describing the Malmquist
problem was 2001 ARA&A,39,67 in which Bruno Leibundgut wrote "A
striking discrepancy is that none of the slowly declining and, hence,
very luminous objects observed in the nearby sample have been
discovered at large distances.

I haven't gone back to check the ARAA paper, but the problem seems to
have gone away. You can't directly measure peak luminosity, of
course, because that's what is used to determine the cosmological
model. (You could measure it if you _assumed_ a particular
cosmological model based on other data.) What you can measure
directly is the stretch factor, and indeed Fig 3b of Goldhaber et
al. (2001) shows the expected slight increase of s with z.

The link below shows the abstract of the paper, and you can get from
that page to the refereed journal article or the preprint:
http://adsabs.harvard.edu/abs/2001ApJ...558..359G

I haven't seen a similar plot for more recent data sets, but there
might be one. It should be easy enough to make one.

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Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123
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On Tue, 03 May 11, Steve Willner wrote:
Eric Flesch writes: (re Malmquist problem)
... 2001 ARA&A,39,67 in which Bruno Leibundgut wrote "A
striking discrepancy is that none of the slowly declining and, hence,
very luminous objects observed in the nearby sample have been
discovered at large distances.

you can measure the stretch factor, and indeed Fig 3b of Goldhaber
et al. (2001) shows the expected slight increase of s with z.

I haven't seen a similar plot for more recent data sets, but there
might be one. It should be easy enough to make one.

You mean like the table at bottom, Steve? It is the Union2 gold set,
from their website, sorted by redshift (but I've had to remove the
low-redshift objects because of the posting size limit). They don't
display the stretch, but do give the curve-fitter "x1" from which I've
calculated the SALT rest-frame stretch using the algorithm from Guy,
J., et al. 2007, A&A, 466, 11. I see no correlation between redshift
and rest-frame stretch, which is fine, except that we should expect a
Malmquist-caused correlation.

That we don't is because the cosmology has been tailored to fit these
observations precisely. The Malmquist effect hasn't been quantified
so hasn't been an input into the resultant cosmology. Lo and behold,
the accelerating expansion!

Now there is a really basic problem here. To use all the information
to yield the result, leaving nothing left over as a check, is what I
call "optimisation" and is basically degenerate because there are no
checks. Without checks, you lose your bearings and veer off course,
which is what the "accerating expansion" looks like to me. I think
the business needs to be reviewed.

name z x1 rest-frame stretch
2005hy 0.1560 1.44 1.115
1999ar 0.1561 -0.51 0.934
e020 0.1590 0.03 0.983
1996r 0.1600 -2.42 0.788
2005gd 0.1610 -0.80 0.910
2005fa 0.1620 1.18 1.090
2005gc 0.1650 0.22 1.000
2005is 0.1720 -0.84 0.906
1997i 0.1720 0.23 1.001
2005ga 0.1740 -0.12 0.969
2005hp 0.1750 -0.93 0.899
1999dr 0.1780 -1.86 0.826
2005hv 0.1790 -0.34 0.949
1997n 0.1800 0.23 1.001
2005ft 0.1810 -0.01 0.979
2005jl 0.1810 -0.34 0.949
k429 0.1810 0.16 0.995
2005gj 0.1830 0.63 1.038
2005id 0.1840 0.63 1.038
2005ko 0.1850 -0.96 0.896
1999dv 0.1860 -0.77 0.912
2005ht 0.1870 0.49 1.025
2005jk 0.1900 -0.70 0.918
2005eg 0.1910 0.83 1.057
2005fu 0.1930 0.06 0.985
2005fy 0.1950 0.48 1.024
2005kn 0.1980 -2.59 0.777
2005iz 0.2020 -2.26 0.798
2005jm 0.2040 0.30 1.008
d086 0.2050 -0.30 0.953
2005ge 0.2060 -0.43 0.941
2005jx 0.2100 -0.48 0.937
d099 0.2110 -0.16 0.966
2005jp 0.2120 -0.10 0.971
2005fp 0.2130 -2.04 0.813
2005jc 0.2130 -0.23 0.959
h363 0.2130 -0.73 0.915
2005mi 0.2140 0.60 1.036
1999dy 0.2150 0.74 1.049
2005ji 0.2160 -0.54 0.932
n404 0.2160 -0.54 0.932
2002kc 0.2160 1.09 1.082
2005fe 0.2170 0.22 1.000
2005lh 0.2180 -1.95 0.820
g005 0.2180 1.34 1.106
2005jo 0.2190 0.22 1.000
2005hu 0.2200 -0.29 0.954
2005gg 0.2300 0.68 1.043
2005fl 0.2340 0.83 1.057
6696 0.2380 3.49 1.302
e132 0.2390 -0.34 0.949
1995ao 0.2400 3.09 1.268
2005ll 0.2440 0.40 1.017
2005gr 0.2450 0.71 1.046
03D3bh 0.2486 0.55 1.031
m039 0.2490 0.68 1.043
2005gf 0.2500 0.16 0.995
2005gs 0.2510 1.44 1.115
2005ia 0.2520 1.46 1.117
2005jz 0.2530 -0.49 0.936
2005le 0.2540 0.75 1.050
2005li 0.2570 -0.91 0.900
2005jb 0.2580 -0.97 0.895
2005gh 0.2590 0.37 1.014
2005ih 0.2590 0.28 1.006
2005ju 0.2590 0.09 0.988
1999du 0.2600 1.29 1.101
2005fd 0.2620 -1.27 0.871
2005fo 0.2620 1.12 1.085
04D3ez 0.2630 -1.01 0.892
2005fi 0.2650 0.69 1.044
2005go 0.2650 -0.04 0.976
m043 0.2660 1.73 1.143
n346 0.2660 2.33 1.199
2005ix 0.2670 -0.35 0.949
1999dx 0.2690 -1.51 0.852
k396 0.2710 -0.04 0.976
2005jy 0.2720 -2.15 0.806
2005mo 0.2740 2.98 1.258
k425 0.2740 -0.08 0.973
2005gw 0.2770 0.53 1.029
1999fw 0.2780 -1.27 0.871
2005gt 0.2790 -1.49 0.854
2005ie 0.2800 -0.67 0.921
2005ig 0.2810 -2.05 0.813
p455 0.2840 -1.12 0.883
03D4ag 0.2850 0.79 1.053
m027 0.2860 0.54 1.030
2005fr 0.2880 -0.05 0.975
2005fx 0.2900 -1.26 0.872
03D3ba 0.2912 0.46 1.022
2005ii 0.2940 0.51 1.027
2005fc 0.2970 0.72 1.047
2005lo 0.2990 -1.85 0.827
2005lf 0.3000 1.12 1.085
2005iv 0.3000 0.14 0.993
1996j 0.3000 -2.33 0.794
2005hs 0.3010 -0.20 0.962
g055 0.3020 1.53 1.124
2005lp 0.3030 2.50 1.215
2005jg 0.3040 -0.93 0.899
d117 0.3090 -1.84 0.827
n278 0.3090 -1.97 0.818
2005it 0.3100 -0.78 0.911
2005ic 0.3110 -0.05 0.975
2005ik 0.3110 -1.09 0.885
2005jd 0.3140 0.45 1.021
m062 0.3140 -0.73 0.915
2005ka 0.3180 2.09 1.176
1997ac 0.3200 0.51 1.027
2005jn 0.3220 0.18 0.996
2005ja 0.3280 0.34 1.011
b016 0.3290 0.34 1.011
03D1fc 0.3310 0.21 0.999
2005gu 0.3320 -0.18 0.964
2005gy 0.3320 0.65 1.040
e029 0.3320 -2.38 0.791
d083 0.3330 1.25 1.097
04D3kr 0.3373 1.10 1.083
2001iw 0.3396 -1.72 0.836
2005fs 0.3400 1.75 1.144
d087 0.3400 -0.05 0.975
g097 0.3400 0.48 1.024
04D3nh 0.3402 0.50 1.026
m193 0.3410 -0.38 0.946
d149 0.3420 0.37 1.014
h364 0.3440 -0.47 0.938
03D1bp 0.3460 -1.15 0.880
h359 0.3480 -0.12 0.969
2005mq 0.3500 0.62 1.037
2005lg 0.3500 1.04 1.077
e136 0.3520 -2.08 0.810
1994f 0.3540 -3.42 0.734
1998as 0.3550 -1.55 0.849
04D2fs 0.3570 -0.08 0.973
04D3fk 0.3578 -0.41 0.943
1688 0.3590 -0.04 0.976
2005jt 0.3610 -1.45 0.857
2005gv 0.3630 0.12 0.991
d093 0.3630 1.09 1.082
2005jj 0.3680 -1.77 0.832
n263 0.3680 -0.97 0.895
04D2cf 0.3690 -0.98 0.894
03D3ay 0.3709 0.25 1.003
1994am 0.3720 -1.12 0.883
1997o 0.3740 1.42 1.113
1994h 0.3740 -0.20 0.962
1994an 0.3780 -1.40 0.861
2005lq 0.3800 0.65 1.040
1996k 0.3800 -1.44 0.857
2005jw 0.3810 1.34 1.106
2005mm 0.3820 -1.87 0.825
1166 0.3820 1.20 1.092
g052 0.3830 -2.04 0.813
1995ba 0.3880 -0.51 0.934
2005kq 0.3890 -0.74 0.915
2005gq 0.3900 -0.25 0.957
5737 0.3930 1.42 1.113
2005mh 0.3950 0.60 1.036
2001iv 0.3965 0.79 1.053
g142 0.3990 -2.84 0.763
1995aw 0.4000 2.54 1.218
2005hq 0.4010 -1.19 0.877
d085 0.4010 0.65 1.040
f308 0.4010 2.55 1.219
k448 0.4010 0.28 1.006
2005iy 0.4040 1.17 1.089
2005hw 0.4100 -1.13 0.882
f076 0.4100 -1.00 0.893
f096 0.4120 -0.01 0.979
04D2fp 0.4150 0.18 0.996
1997am 0.4160 0.44 1.021
k485 0.4160 -0.51 0.934
1994al 0.4200 -0.80 0.910
g133 0.4210 2.46 1.211
h342 0.4210 1.36 1.107
2005jv 0.4220 0.37 1.014
f235 0.4220 -1.19 0.877
2002ab 0.4230 -2.08 0.810
1994g 0.4250 -1.18 0.878
b020 0.4250 -1.42 0.859
b013 0.4260 -0.60 0.927
e148 0.4290 -1.10 0.885
1996e 0.4300 -1.52 0.851
1996u 0.4300 -0.83 0.907
1997q 0.4300 -0.26 0.957
1996cn 0.4300 -0.21 0.961
1998ba 0.4300 -0.70 0.918
04D2gb 0.4300 -2.30 0.796
d089 0.4360 0.22 1.000
d097 0.4360 1.76 1.145
1997ce 0.4400 -1.62 0.844
1998aw 0.4400 0.53 1.029
03D3aw 0.4490 -0.13 0.968
1997ai 0.4500 -2.69 0.772
1996cm 0.4500 -0.24 0.958
1995az 0.4500 -0.06 0.975
04D3gt 0.4510 -0.19 0.963
1995aq 0.4530 -0.98 0.894
1999ff 0.4550 -1.44 0.857
04Yow 0.4600 0.13 0.992
03D3cd 0.4607 2.20 1.187
03D3cc 0.4627 0.48 1.024
m158 0.4630 0.55 1.031
1995ar 0.4650 0.42 1.019
03D4au 0.4680 0.47 1.023
e108 0.4690 2.01 1.169
04D3df 0.4700 -2.33 0.794
1997p 0.4720 -0.63 0.924
2002dc 0.4750 -1.20 0.876
1999fn 0.4770 0.76 1.051
1995k 0.4790 -0.23 0.959
1995ay 0.4800 -1.51 0.852
1996cg 0.4900 0.10 0.989
04Haw 0.4900 -0.04 0.976
g160 0.4930 1.44 1.115
1996ci 0.4950 -0.91 0.900
h319 0.4950 1.06 1.079
03D1ax 0.4960 -1.00 0.893
1998ax 0.4970 1.05 1.078
e149 0.4970 -0.54 0.932
1995as 0.4980 0.26 1.004
1997cj 0.5000 -0.71 0.917
03D1au 0.5043 1.04 1.077
p524 0.5080 0.86 1.060
g120 0.5100 0.21 0.999
2001gy 0.5110 -0.31 0.952
2002ad 0.5140 1.68 1.138
d084 0.5190 0.80 1.054
04D2gc 0.5210 0.93 1.067
05Zwi 0.5210 1.10 1.083
n258 0.5220 -0.81 0.909
1997h 0.5260 -0.53 0.933
04D1ak 0.5260 -1.99 0.817
2002hr 0.5260 2.37 1.203
2001jp 0.5280 -1.17 0.879
n285 0.5280 1.11 1.084
03D3af 0.5320 -0.36 0.948
f011 0.5390 -1.45 0.857
1997eq 0.5400 -0.57 0.929
f244 0.5400 -0.59 0.928
2000fr 0.5430 0.69 1.044
03D1gt 0.5480 -2.20 0.802
1997l 0.5500 2.13 1.180
04D4bq 0.5500 0.02 0.982
04D3hn 0.5516 -0.91 0.900
2001go 0.5520 -1.15 0.880
04D1ag 0.5570 -0.46 0.939
f041 0.5610 2.45 1.210
m034 0.5620 1.00 1.073
k411 0.5640 -0.63 0.924
2001iy 0.5680 0.62 1.037
1996i 0.5700 -1.56 0.848
1996cf 0.5700 0.29 1.007
03D4gl 0.5710 -0.59 0.928
03D4bc 0.5720 -2.14 0.806
1997af 0.5790 -1.09 0.885
1997f 0.5800 3.49 1.302
1997aj 0.5810 0.71 1.046
03D4gf 0.5810 0.29 1.007
m138 0.5810 1.43 1.114
03D1aw 0.5817 -0.04 0.976
k430 0.5820 -0.44 0.941
d058 0.5830 0.17 0.996
b010 0.5910 2.00 1.168
1997k 0.5920 3.16 1.274
03D4gg 0.5920 0.85 1.059
f216 0.5990 -3.25 0.742
h323 0.6030 -0.31 0.952
03D4dy 0.6040 0.89 1.063
04D3do 0.6100 -1.15 0.880
e138 0.6120 1.04 1.077
04D4an 0.6130 -1.41 0.860
p534 0.6130 -0.31 0.952
1995ax 0.6150 0.87 1.061
f231 0.6190 1.24 1.096
1996h 0.6200 3.60 1.311
04D3co 0.6200 -0.95 0.897
03D4dh 0.6268 0.83 1.057
e140 0.6310 -0.44 0.941
n256 0.6310 0.36 1.013
03D4at 0.6330 -0.47 0.938
g050 0.6330 -0.22 0.960
1998be 0.6400 -2.27 0.798
1998ay 0.6400 0.23 1.001
2003be 0.6400 -1.08 0.886
04D3cy 0.6430 0.04 0.984
e147 0.6450 -0.38 0.946
1995at 0.6550 1.12 1.085
1996ck 0.6560 -1.15 0.880
1997r 0.6570 -0.09 0.972
2003bd 0.6700 -1.19 0.877
m226 0.6710 1.26 1.098
2001gq 0.6710 0.46 1.022
03D1co 0.6790 0.67 1.042
k441 0.6800 1.45 1.116
g240 0.6870 -0.05 0.975
h300 0.6870 0.73 1.048
03D1fl 0.6880 -0.07 0.974
04D2iu 0.6910 -1.83 0.828
03D4cz 0.6950 -2.36 0.792
2001jb 0.6980 -3.29 0.740
04D2gp 0.7070 -1.95 0.820
04D3is 0.7100 0.18 0.996
2001ix 0.7110 0.36 1.013
04D1aj 0.7210 0.52 1.028
04D3fq 0.7300 -0.76 0.913
2002kd 0.7350 -0.26 0.957
04Rak 0.7400 -0.11 0.970
04D2ja 0.7410 0.02 0.982
1998bi 0.7500 -0.09 0.972
04D3ks 0.7520 0.33 1.010
04D3oe 0.7560 -1.84 0.827
1997g 0.7630 -0.86 0.904
2001fo 0.7720 0.02 0.982
1997ez 0.7800 0.94 1.068
p528 0.7810 -0.55 0.931
03D4fd 0.7910 -0.17 0.965
2001hx 0.7990 1.87 1.156
03D1fq 0.8000 -1.68 0.839
04D3ny 0.8100 0.09 0.988
04D4dm 0.8110 0.51 1.027
2001hy 0.8120 -2.65 0.774
2001jf 0.8150 0.09 0.988
1999fj 0.8160 0.24 1.002
04D3nc 0.8170 1.39 1.110
03D4cn 0.8180 -2.62 0.776
04D3lu 0.8218 -0.36 0.948
1997ap 0.8300 0.33 1.010
04D3cp 0.8300 0.84 1.058
2001hs 0.8330 1.50 1.121
05Spo 0.8390 -0.10 0.971
04D4bk 0.8400 0.76 1.051
2003eq 0.8400 -0.02 0.978
04Man 0.8540 -1.15 0.880
2002x 0.8590 -1.09 0.885
1997ek 0.8600 0.03 0.983
03D1ew 0.8680 0.19 0.997
03D1cm 0.8700 3.41 1.295
2001fs 0.8740 -0.39 0.945
2001hu 0.8820 1.78 1.147
2001jh 0.8850 0.99 1.072
2003eb 0.9000 -0.06 0.975
03D4di 0.9050 0.86 1.060
04D3gx 0.9100 -0.52 0.934
03D4cy 0.9271 -0.14 0.967
04D3ki 0.9300 -1.03 0.890
2003XX 0.9350 -0.47 0.938
2001kd 0.9360 -2.05 0.813
03D4cx 0.9490 -0.27 0.956
04D3ml 0.9500 0.86 1.060
1999fm 0.9500 1.58 1.128
2002dd 0.9500 1.38 1.109
2001cw 0.9530 0.14 0.993
04Tha 0.9540 -0.70 0.918
2003es 0.9540 -1.12 0.883
04D3nr 0.9600 0.68 1.043
04D4dw 0.9610 0.07 0.986
1997ck 0.9700 0.53 1.029
04Pat 0.9700 -0.84 0.906
04Omb 0.9750 1.89 1.158
2001jm 0.9780 -0.54 0.932
04D3lp 0.9830 -1.37 0.863
04D3dd 1.0100 0.47 1.023
05Str 1.0100 3.46 1.300
04Eag 1.0200 -0.15 0.966
05Fer 1.0200 1.13 1.086
2001hb 1.0300 1.30 1.102
1999fk 1.0570 -0.28 0.955
05Gab 1.1200 0.11 0.990
2001gn 1.1240 0.65 1.040
04Gre 1.1400 0.15 0.994
2002ki 1.1400 -0.11 0.970
05Red 1.1900 -1.22 0.875
05Lan 1.2300 -0.56 0.930
05Koe 1.2300 -0.23 0.959
2003az 1.2650 0.27 1.005
2002fw 1.3000 0.25 1.003
2002hp 1.3050 -1.07 0.887
2003aj 1.3070 -0.34 0.949
2003dy 1.3400 1.79 1.148
04Mcg 1.3700 0.67 1.042
04Sas 1.3900 -0.23 0.959
2002fx 1.4000 1.07 1.080

On May 4, 1:08 am, Eric Flesch wrote:
[...]

That we don't is because the cosmology has been tailored to fit these
observations precisely. The Malmquist effect hasn't been quantified
so hasn't been an input into the resultant cosmology. Lo and behold,
the accelerating expansion!

How is a magnitude based selection bias going to give accelerated
expansion? I have no idea what you are talking about, which confuses
me.

We know that SN1a have a largely constant integrated luminosity, which
can be directly established by using distance measures that
independently determine redshift. That way you can avoid claims of
circular argument.

My problem with your argument is that Malmquist bias (which I mentally
equate to 'selection bias', because it is) is that the bias covers the
problem of missing data for a magnitude limited survey. Eg, you can't
account for what you can't see. But why does this meaningfully apply
to SN1a's?

What population of SN1a's do you imagine are out there which we are
not seeing? Other than the hopefully-obvious population of SN1a's that
are simply too far away and thus currently invisible.

Now there is a really basic problem here. To use all the information
to yield the result, leaving nothing left over as a check, is what I
call "optimisation" and is basically degenerate because there are no
checks. Without checks, you lose your bearings and veer off course,
which is what the "accerating expansion" looks like to me. I think
the business needs to be reviewed.

Er, what?

How do you match what you just said with the basic scientific process
of producing a model, and comparing the model with data? That process
eliminated unaccelerated expansion, and confirmed accelerated
expansion.

[...]

In article ,
Eric Flesch writes:
It is the Union2 gold set,
from their website, sorted by redshift. They don't
display the stretch, but do give the curve-fitter "x1" from which I've
calculated the SALT rest-frame stretch using the algorithm from Guy,
J., et al. 2007, A&A, 466, 11.

I haven't gone back to check this, but as long as x1 gives s
uniquely, it should be fine. Goldhaber et al. show stretch values
ranging between 0.8 and 1.2, and at first glance your numbers seem to
show lower scatter.

I see no correlation between redshift
and rest-frame stretch, which is fine, except that we should expect a
Malmquist-caused correlation.

How big do you expect it to be? Bear in mind that the discovery
images will typically have high S/N (because they are the same images
used to measure magnitudes at late times).

That we don't is because the cosmology has been tailored to fit these
observations precisely.

Neither the redshift nor the stretch depends on cosmology; both are
directly measured from the data. You are indeed correct that the
cosmology has been tailored to fit the peak magnitudes, though the
result is consistent with many other types of data.

There are several competing groups working on the supernovae, so if
there were any obvious errors, most likely someone would have caught
them. That's no guarantee, of course, but merely asserting
"something must be wrong" is not useful.

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