Culture and Religion

A world view where the guide for society is based on human nature,
 not on ancient scriptures.  Home  or Topic Groups

Supernova Luminosity Curve Stretching in Time Updated

Astronomers can use a supernova as a standard candle.
An innovation in 1998 used the supernova data from 'near and far' events to make conclusions about the universe expansion over time.
I posted about this topic on September 20 but there is more that must be said about the study's analysis. The conclusions cannot be justified because they are based on invalid manipulations of the light curve, the basis of the standard candle.

Rather than identifying changes, this new post is clearer to present a coherent story. That old post remains unchanged. This post is long but the flawed study was important.

The 1998 study is attached.

excerpt ===
The accelerated expansion was discovered during 1998, by two independent projects, the Supernova Cosmology Project and the High-Z Supernova Search Team, which both used distant type Ia supernovae to measure the acceleration.
===

my comments below apply to that prestigious project.

From the DOE Lawrence Berkeley National Laboratory:

excerpt ===
The surprising discovery that the expansion of the universe is accelerating, and thus is likely to go on expanding forever, is based on observations of type Ia supernovae, very bright astronomical "standard candles" that all have the same intrinsic brightness. Thus how bright they appear reveals their distance.

By comparing the distance of these exploding stars with the redshifts of their home galaxies, researchers can calculate how fast the universe was expanding at different times in its history. Good results depend upon observing many type Ia supernovae, both near and far. Employing supercomputer facilities at the National Energy Research Scientific Computing Center (NERSC) located at Berkeley Lab, the Supernova Cosmology Project has fully analyzed the first 42 out of the more than 80 supernovae it has discovered, and more analysis is in progress.

He adds, "Type Ia supernovae are so similar, whether nearby or far away, that the time at which an explosion started can be determined just from looking at its spectrum. Type Ia supernovae which exploded when the universe was half its present age behave the same as they do today."
===

More details and comments will follow.

The assumption is the supernova luminosity is always reliable.

The other assumption is the galaxy's distance from red shift is correct and indicates the rough time of the supernova.
This assumption about a galaxy  is wrong.

The supernova is considered the standard candle, so its host should never be used to change the standard candle.
If the observed brightness has dimmed for a standard candle then the dimming is only by distance.

For example M31 has a blue shift so a standard candle, Cepheids, are used for its distance. It cannot have a negative distance from its negative velocity.
The Magellanic Clouds have large red shifts so Cepheids are used to determine their distances another, better way.


The statement  "Type Ia supernovae are so similar, whether nearby or far away" is a confirmation of regardless of whether the host galaxy distance is right the supernova IA could be a  standard candle to replace the galaxy's distance by red shift - but only when used correctly.

The Supernova Cosmology Project document is attached (pdf from 2001).

excerpt===
The basic idea is that you want to find an object of known brightness, a “standard candle," and then plot it on the astronomer’s Hubble diagram (Fig. 1), which is a plot of brightness (magnitude) against redshift. We should interpret this graph as follows: for an object of known brightness, the fainter the object the farther away it is and the further back in time you are looking, so you can treat the y-axis as the time axis. The x-axis, the redshift, is a very direct measurement of the relative expansion of the universe, because as the universe expands the wavelengths of the photons travelling to us stretch exactly proportionately—and that is the redshift. Thus the Hubble diagram is showing you the “stretching" of the universe as a function of time. As you look farther and farther away, and further back in time, you can find the deviations in the expansion rate that are caused by the cosmological parameters.
===

my comment:
This is an incredible mistake: 'as the universe expands the wavelengths of the photons travelling to us stretch exactly proportionately—and that is the redshift. '

NO
Only one wavelength is usually red shifted for distant galaxies: the hydrogen lyman-alpha wavelength at 21.567 nm. The rest of the spectrum is intact. ALL wavelengths are not being stretched. This is never observed.
In this study they found the thermal radiation spectrum was shifted for a hot moving object, part of the supernova event.

Since the wavelength is related to the energy of light (or a photon in their text) proposing all  wavelengths increase during the light travel over the expanse of the universe means much energy is being lost from light during its travel, contrary to the conservation of energy. This is definitely not happening.

Perhaps the scientists did not make this mistake, just the author, but the text is very distracting given that problematic result. Hydrogen absorption line red shifts are in only one wavelength, not all, and come from hydrogen atoms encountered over the distance the light travels across the integalactic medium. Therefore this absorption line is affected by many atoms and is not reliable.

===
Figure 1: The Hubble plot: A history of the “size" of the Universe.
===

my comments:
Figure 1 indicates terrible confusion. In the past for cosmology, the luminosity of the supernova light curve was used to calculate the distance for that dimming. It is called a 'standard candle' for that purpose.
Figure 1 indicates the luminosity reduction (y-axis) is directly proportional to the red shift of the host galaxy (x-axis ).

because the graph shows dimming increases with red shift (or distance), the graph claims this conclusion:  'More redshift = Faster expansion in past= Expansion is slowing = More mass'

Dimming with distance is what light does but does not justify a conclusion about the past.
A red shift of a supernova absolutely has no connection to distance or time, neither does the galaxy red shift (but that is assumed by mistake).
When a supernova is analyzed to determine a relative velocity then that result is for only that object.
Any velocity of a separate  object even when near a galaxy has no connection to the distance to that object or the galaxy.

The comment in the upper right corner of figure 1 about the universe expansion has no justification in this study.

excerpt of the 'new' step in this analysis ===

Before this high-redshift supernova data can be plotted on the Hubble diagram [probably a reference to Figure 1] and the cosmological parameters fitted, there are two small additional analysis steps necessary in order to compare the distant supernovae to the nearby supernovae on the same Hubble plot. First of all, although most type Ia supernovae follow a very similar light curve, there are a few outliers that are a little bit brighter or a little bit fainter. In the early 1990s, it was pointed out by Mark Phillips that there is an easy way to distinguish these supernovae, and recognize the slightly brighter ones and slightly fainter ones, using the timescale of the events. Phillips  noted that the decline rate in the first 15 days after maximum provides a good parameterization of the timescale, and that this is a good predictor of how bright the supernova will be.

Later, [they] showed another elegant statistical method which effectively added and subtracted shoulders on the light curve to achieve the same sort of timescale characterization. Finally, our group developed a third method, which we call the timescale stretch factor method, in which we simply stretch or contract the timescale of the event by a linear stretch factor, s. This also predicts very nicely the brightness of the supernova: The s > 1 supernovae are the brighter ones and the s < 1 supernovae are the fainter ones.
===

my comment:
The new step involves a linear stretch factor, so this 'predicts very nicely' the brightness.
Later in this document 'stretch factor refers to a hot object moving away from the supernova. They are mixing measurements without justification.

excerpt ===
'
Figure 5: Upper panel: The range of lightcurve for low-redshift supernovae discovered by the Calan/Tololo Supernova Survey. At these redshifts, the relative distances can be determined (from redshift), so their relative brightnesses are known. Lower panel: The same lightcurves after calibrating the supernova brightness using the “stretch” of the timescale of the lightcurve as an indicator of brightness (and the color at peak as an indicator of dust absorption).
===

my comment:
The supernova  light curve is 'calibrated' by the red shift of a separate object but this wrong. The ejected object has nothing to with the time scale. The velocity of the ejected object is used to stretch the light curve.
As the light curve is assumed to be reliable this usage means the observed light curve is wrong but it is stretched by an inappropriate factor to fix it. This is wrong.

Figure 6 is a comparison of two spectra, B and R.

excerpt ===
'
Figure 6: Slightly different parts of the supernova spectrum are observed through the “B filter” transmission function at low redshift (upper panel) and through the “R filter” transmission function at high redshift (lower panel). This small difference is accounted for by the “cross-filter K-correction”
===

my comment:
I My interpretation of this figure 6 implies there is an interpretation problem in the study when this is called time dilation. This wavelength distribution is thermal radiation with the peak indicating a temperature so curve B appears hotter than curve R, with the  B peak at a shorter wavelength.
If the peaks and patterns in thermal radiation were different between B and R I would have assumed different temperatures. They treat this  shift as a time dilation.
Instead this difference in spectra is just a red shift. This perceived dilation is wrong. B has a peak wavelength at about 4000 while curve R has a peak at about 6000.
For reference:
B peaking at 4000 Ang is 7244K.
R peaking at 6000 Ang is 4829K.

The calculated red shift from 4000 to 6000 (Figure 10 uses Angstroms) is z=0.5
The figure shows z=0.45 but the exact wavelengths are not provided for a better calculation here.

These spectrum curves represent a blackbody temperature curve of an object in thermal equilibrium. I will not debate whether this is a correct temperature because the value is not part of the analysis. Any doppler effect measured is for only this object. This separate object's motion is not related to any assumed motion of the host galaxy. The object's red shift certainly cannot be used to calculate its distance.
A body's measured temperature can change by its rapid motion, as observed by this study.
The supernova has no red shift in an absorption line or emission line being shifted for this analysis. Only the red shift in the galaxy hydrogen absorption line is used (incorrectly) for a galaxy distance.
In this figure the red shift is observed in comparing the range of wavelengths for thermal radiation, assuming both have the same temperature, but then shifted by a different z.
Apparently the study found several supernovae with their thermal radiation spectrum shifted in a similar manner.

This comparison of  motions of these objects (by their measured temperature) has no connection to time. However this study uses the object's red shift to stretch the observed light curve. This application cannot be justified.

The 'stretch factor' is also mentioned in figure 5 where a stretch factor is applied to the luminosity curve.
The light curves should be consistent when the supernovae are consistent but these supernovae with an ejected object are not consistent until their timing is stretched, or 'fixed'.

excerpt ===
This is one of the most dramatic examples of a macroscopic time dilation that you will get to see. If you take out that (1+z) time dilation, and also remove the small variations in the stretch factor, the low redshift and high redshift composite light curves now lay right on top of each other. This shows that the supernovae are very similar across redshifts and that the K-correction does an excellent job in bringing them in line with each other.
===

my comment:

There is no such thing as time dilation for a supernova. A hot moving object at the supernova is emitting thermal radiation and its spectrum is shifted by the Doppler effect on electromagnetic radiation. Surprisingly, this object shows a red shift so it is moving away from Earth. I expected a blue shift from an explosive event.

Figures 7 and 8  are irrelevant because the relative velocities observed among a number of supernovae have nothing to do with the mass density of the universe.

excerpt from below figure 9===


This result can also be interpreted as a measurement of the age of the universe,
if you know the current expansion rate (i.e., the current Hubble constant).
This is shown on the plot with isochrons of age for a given mass density and cosmological constant (see Fig. 9). The supernova confidence region picks off a value of about 14.5 billion years, or 15 billion years along the flat universe line.
These values are for a Hubble constant of 65 km/s/Mpc; if we had chosen a Hubble constant that was 10 percent higher we would have found an age that was 10 percent lower. In either case, there no longer appears to be an “age crisis" in which the oldest stars seemed to be older than the age of universe.
===

my comment:

Figure 9 is a completely worthless plot.
Whether supernovae had different z values compared to their host galaxies has absolutely nothing to do with the mass density of the universe.

a subsequent excerpt:

'
These results can also be compared with those from other methods for measuring the cosmological parameters. In particular, we can ask to what extent do we know that we live along the flat universe line, because our measurement does not constrain that very well. The cosmic microwave background, the leftover glow from the very dense period at the beginning of the big bang, is a very good indicator of how curved the universe is. We are beginning to see CMB data coming in that is starting to constrain the curvature. Although much better data should be available within the next few years, we can already begin to rule out the upper right (“over-closed") and lower left (very “open") regions . This has been taken by some as suggestive that we will find the answer to be a flat universe. If you put the CMB data together with the supernova data, you find a result that centers quite close to the flat universe line, with mass density approximately 0.3 and vacuum energy density approximately 0.7.
'

my comment:
Since the CMB has been shown to be the background noise from the Earth's oceans, it is not meaningful to know there is a common conclusion with CMB analysis after an inappropriate time stretching of the light curve was applied here.

The paper concludes with a question about the level of confidence.

excerpt from section 7 ===
'
Given the surprising nature of this result, it is important to ask how strongly it
can be believed. First of all, if you believe that we have evidence for a flat universe
from the cosmic microwave background data—or if you like the inflationary universe model which predicts a flat universe—then the supernova results are very strong.

such higher redshifts are useful in addressing both loopholes, evolution and gray dust. This is because the curve on the Hubble diagram that is predicted for a cosmology with a positive cosmological constant is fainter at z = 0.5 than the curve for a universe with no cosmological constant, but at much higher redshifts the two curves come back together and cross. This behavior is very difficult to mimic with an evolutionary effect.
===

my trailing comment:
After figure 6 the main focus of the document is whether is universe is open or closed and determining a cosmological parameter based this study's results.
This study seeks to connect supernovae events in remote galaxies to concluions about the entire universe. This case was not convincing.

A section is titled : Plugging the remaining loopholes

This section has figure 10 with absorption lines in a broad spectrum so each must be from a star still luminous after the supernova. There are many red shifted absorption lines from calcium, iron, silicon and cobalt. Each spectrum, from six  different 'nearby' supernovae  is not like figure 6 showing thermal radiation.
Below the figure is text noting this data compares SN 1997ap at z=0.83

These spectra are not comparable to figure 6. This figure 10 compares stars measured after the event while figure 6 was only a hot ejected object which is rapidly receding.

The irony with figure 10 is absorption lines indicate motions of atoms in the star's stmosphere being above the light source.
These spectra indicate presence of elements but nothing about the star, certainly nothing about the star's motion.
Figure 10 is presented to show red shifts of 6 supernovae velocities but in reality it does not.

excerpt from the end of the source===

It now appears that we live in a universe that will continue to accelerate forever in its expansion—but the jury is still out; and we have only begun to take our first steps in cosmology as an empirical science.
===

my comment:
My verdict is: guilty of wrong conclusions based on wrong interpretations.
An empirical science is one based on evidence.
Cosmology continues to be based on interpretation. Whenever the interpretations are wrong the science is damaged by conclusions based on them.

The accelerating expansion is the conclusion based on wrong interpretations of spectral lines.
This study confirms this is only an effort to confirm assumptions not to learn what is real based on evidence.

I My summation of this study:

Viewing light curves for many supernova found them to be very similar. However the 'high red shift' supernova light curve had to be 'time stretched' to conform to others. Instead of using supernovae to confirm the universe expansion the data manipulation implies supernovae are not consistent across the data set.
The determination of a red shift of a hot object near the supernova adds nothing to a procedure of using a supernova as a standard candle . The value and polarity of this separate object's velocity might be interesting trivia but it can be ignored.

Cosmology needs standard candles to avoid using problematic absorption lines.
Rather than being encouraging, this study implies supernovae are not consistent, a requirement for a standard candle.

link

Hit back to go to previous page in history.

Here is the list of topics in this Cosmology Topic Group .

Ctrl + for zoom in;  Ctrl - for zoom out ;  Ctrl 0 for no zoom;
triple-tap for zoom to fit;  pinch for zoom change;  pinched for no zoom