More from Arp et al.

[dgruss23]

Actually, I thought that it appeared only Arpians were interested in this class of objects, which I thought was kind of interesting.

You can do the google search yourself. Type in ["sci galaxies" morphology] and you get ~445 sites. Notice the first page is almost entirely a list of links to papers authored by.... David Russell! Those papers not authored by you are authored by.... Halton Arp! Well, that's weird.

OK, how many of these 445 "ScI" sites also mention "intrinsic" in some fashion? So let's intersect the two sets. Type in ["sci galaxies" morphology intrinsic] and what do you get? 428 sites! So 96% of the sites that contain the phrase "ScI galaxies" also contain the word "intrinsic."

I realize that sites such as Astro-ph for busy people that compile a large list of papers and abstracts may be contaminating this little exercise. Still, I believe the statistics show an overdensity of Arpian interest in these ScI galaxies. I don't think it's out of line to wonder why.

As I linked to, some researchers do utilize the classification system with emphasis on ScI's, but its not common because most researchers take a broader approach - lumping them all together without concern for luminosity class influence.

As I said, I haven't gotten into the details of your papers much. I have, however, made some general criticisms about how close Virgo is, what a huge cluster it is, how it is apparently made up of at least three major sub-clusters, how it is oriented with respect to our vantage, and how it is unique in composition and dynamics -- all of which are likely to have some relevance to your findings.

The problem with that criticism is that the ScI's and the large Sab/Sb's in question are not limited to any one subcluster, nor are they found to have a different TFR distance distribution or mean distance compared with each other or the Ellipticals.

One referee suggested the morphological density relation (ellipticals in clusters are found in denser environments) would explain it. But the MD relation can only explain why spirals have larger peculiar motions than ellipticals (because the spirals are more likely to be found on the cluster outskirts and thus more likely to be infalling). It cannot explain why ScI spirals all have excess redshift while the large Sab/Sb spirals have a deficit of redshift. In Virgo all the ScI's would be infalling away from the Milky Way, while all the large Sab/Sb's would be infalling toward the Milky way. There is no reason for such a phenomenon.

What I said was....
I found quite a few papers referring to this classification of objects, but none of them provided any definition. None of the standard schemes mentioned it. Not everyone has had the good fortune to have been able to spend "years studying the relevant research literature." Certainly not keyboardists with a bit of math background and a straight job.

I don't expect everyone to have such "good fortune" ... but perhaps an ask for clarification before you a fatal flaw is claimed approach might be more beneficial to the discussion.

I have no doubt you know a lot about what you're talking about. I disagree with the conclusion you're shooting for in your research program, but at least you're going about it with appropriate rigor.

Thanks!

[Thanatos]

I didn't calculate a single redshift distance for Virgo Cluster Galaxies.

My apologies. I thought you were claiming an inexplicable difference between redshift and TFR distances, and assumed you meant 'peculiar velocity' was the difference between the two. I concede I missed your point.

[Nereid]

Cougar has already noted one difficulty with this kind of analysis; I'll note another: Russell gives the "mean peculiar velocity" as "+808 km s-1" for one group, and "-868 km s-1" for the other*. Compare this with +753 and -577 for the four "Cepheid" galaxies. Are they the same? sufficiently similar? too small a sample to tell? something else?

Whatever the answer is, "exactly" is either too strong or "the trend" extremely poorly constrained.

*As I noted earlier, there are no "error bars". I also note that Russell's analysis is considerably more extensive than TomT's summary, as I'm sure all readers of this post are well aware.

I don't mind repeating until I make my point clear. I'm probably just not communicating clearly enough.

The "trend" as I've stated before is given on p.2, Par. 2.

"Arp(1987, 1988, 1990, 1994, 1998a,b) has found evidence that late type spiral galaxies (Sbc/Sc) and smaller companion galaxies tend to have a systematic excess redshift relative to larger early type (Sa/Sb) galaxies. Russell (2002) utilized linear diameters as a test and confirmed this phenomenon." The items in () are references in the paper.

So the "trend" is: one type of galaxy having systematic excess redshift relative to another type of galaxy, when both types are in the same cluster or group.

Russell presents further evidence illustrating this trend in this paper. He shows this in Tables II, III, and IV.
In Table III he shows this for ScI's relative to Sab/Sb's in Virgo for 17 galaxies, 4 of which have Cepheid distances available. The Cepheid set and the total set both show the exact same trend as was found in the 7 references given above.
I am aware of the claims of not enough galaxies in the samples, and "cherry picking". I don't mind digging into the "cherry picking" claim myself, but it will take some time. One thought on this is that "cherry picking" would be such an obvious and self defeating act, that it is preposterous to claim a person of Russell's reputation and ability would even think of it, let alone even consider doing it. Also, I hope that everyone now sees that Table III is a subset of Table II, and that Table III has the galaxy types comparable to those in the referenced papers.
As far as comparing the "Cepheid" galaxies with the total, they show the "same" trend as the references. As far as the number being sufficient, I think it's all the Cepheid data available for this cluster, so what choice is there on sample size. We can say with certainty, that what IS available does confirm the trend.
I also point out again that the Pisces and Serpens groups in Table IV show the exact same trend.
Then further types of evidence are brought forward in the remaining sections of the paper, but perhaps we should finish the current discussion first, and this includes the Pisces and Serpens filaments.
TomT

As noted earlier, the Table III PV72 column lists values, to four significant places, but no error bars.

One way to get a handle on the size of the error bars is to compare PV72 values calculated using different assumption (or inputs).

For example, in the Russell paper, the two groups average 718 km/s (ScI, 9 datapoints) and -868 km/s (Sab/Sb, 8), with standard deviations of 389 and 212 km/s respectively.

Using an average TFR (i.e. averaging eqns 6 and 7, unweighted), and 'current' LEDA inputs, gives group averages of 945 (sd 357) and -1055 (sd 389) (all km/s, as are all below, unless otherwise noted).

However, using 'current' values from LEDA*, and the same TD-TFR as in the paper, the group averages become 791 (sd 361) and -861 (sd 326) respectively.

Perhaps most interesting is the range of the deltas (Russell's Table III - PV72 calculated using 'current' LEDA values): 78 to -330 (ScI group; sd 133) and 587 to -389 (Sab/Sb group; sd 269).

It's hard to interpret what these calculations tell us, other than that the changes in the LEDA homogenisation, between when Russell downloaded the data, to use to calculate the Table III PV72 values, and 'today' produced some rather large, individual changes - many of them considerably greater than the V_rot values (for example).

(1)Four of the Virgo galaxies in Russell's Table III use Cepheid determined distances. So we can test the method using only those, and not worry about rotation rates, and magnitudes. The 3 of the ScI Group, NGC 4321, 4535, and 4536 have PV72 values of +595, +891 and +773. The single galaxy of the Sab/Sb Group, NGC 4548, has PV72 of -577. These are results for individual galaxies and they exhibit exactly the trend Russell is claiming.

There are 1,500 to 2,000 galaxies in the Virgo cluster! If I can select a specific four out of that set, I can prove to you just about any trend you want. Selecting 10 or 20 and trying to reach some conclusion is pretty darn iffy as well.

It is perhaps in this regard that the 'homogenisation changes' should be considered (one of the 'Cepheid galaxies' (NGC 4321) is at the extreme in its group, for example, illustrating that with tiny samples like these 'trend' conclusions are unreliable).

There has been considerable discussion of the 'selection effects' involved in 'the 17'; I decided to take a look at these, from a slightly different perspective (see next post).

*The homogonisation of the data is on-going, so what Russell used as inputs have changed.

[Nereid]

Two posts in this thread to note, wrt Table III and selection criteria: #2605 (dgruss23; #2612 (also dgruss23) is also useful) and #2516 (Thanatos; TomT's #2662 also uses this data).

The question I am interested in exploring, in this series of posts, is how selection criteria can produce interesting results, using the Virgo galaxies.

The first, and most obvious, thing to note is just how few of the Virgo galaxies are included in either list (43 and 92 out of ~2000)!

Next, how complete are the 'big bright' galaxies in the two samples? The selection criteria include "LEDA database [...] galaxies in Virgo with B-band magnitudes and rotational velocities ...", with no (apparent) attempt made to estimate completeness or selection effects (for inclusion in the LEDA database) - if, one day, a complete survey of all Virgo galaxies is made, how many more would meet these criteria?

Then there are the morphological class and type criteria - essential for categorising into one line or another in Table II, and inclusion in Table III.

Let's consider t ("Morphological type code"). The 17 in Table III range, in t, from 1.4 to 5.2; in Thanatos' 92, 0.2 to 6.9 (of which 55 are in the "Table III" range).

And lc ("Luminosity class code"): 1.0 to 7.0 (Table III) vs 1.0 to 7 (though only 60 of the 92 have a value for lc); and only 44* of the 55 in the "Table III" t range have lc values).

(We don't need to consider either bri₂₅ or V_rot; Thanatos' selection criteria are the same as Russell's).

So what of these 11 (Virgo galaxies that meet the Russell criteria, except that there is no "lc" code in LEDA)? How should they be treated, for the purposes of showing there is 'intrinsic redshift'?

But there are other selection criteria - there's inclination (which is covered in #2612, but not the paper) and Seyferts (which are put into the ScI group).

5 of the 44 have inclinations outside the selection criterion**, and I can't see how to select for "Seyfert" in LEDA - so there seems to be no way to estimate how this criterion affects the results (e.g. how many "Virgo Seyferts" are not among the 9 galaxies in the ScI group in Table III?).

We can, however, ask what effect classifying the 4 Seyferts as Sab/Sb (and not ScI) would have, on the 'intrinsic redshift' conclusion (note that by the LEDA t and lc values, all 4 Seyferts would belong to the Sab/Sb group, they get classified as belonging to the ScI groups solely because they are Seyferts).

The first result is that the number of remaining in the ScI group is probably too small to allow much of a conclusion at all.

The second is that TomT's 'Cepheid distance trend check' looks better! The average PV72 for the Sab/Sb group becomes -332, and NGC 4548's PV72 is -414 (no change for the ScI group, except that there are now only 2 galaxies without Cepheid distances in the group, instead of 6).

The third is that, to the extent an ScI-Sab/Sb group comparison remains meaningful, the 'intrinsic redshift' signal becomes weak - the ScI group mean goes from 791 to 843 (and the range from [39, 1312] to [561,1312]), and the Sab/Sb group mean from -861 to -332 (range widens, from [-1536, -414] to [-1536, 1036]) - IOW, for the Virgo galaxies, the 'intrinsic redshift' conclusion depends strongly on moving the Seyfert subset from the Sab/Sb group (which is what they'd be classified as, using only t and lc) to the ScI group.

post #2632 (dgruss23) addresses some of the completeness aspects of the Virgo galaxy intrinsic redshift conclusions, and overlaps with part of this post, so I'll consider that next, before looking further into selection effects (and empirical relationships).

*This is close to "the 43", but it's a coincidence - the paper uses log V_rot > 1.89; dgruss23's post #2605 "Rotational velocity should exceed 100 km s-1"
**Interpreted liberally, per dgruss23's posts in this thread.

[Nereid]

[snip]

Without calculating TFR distances, let's just assume they are cluster members and calculate the mean redshift breaking them down by morphology:

There were 4 ScI's/Seyferts among these with a mean redshift of 2276 km s-1 (Table II group mean was 1855 km s-1).

There were 10 Sbc/ScIII's with a mean redshift of 1537 km s-1 (Table II group mean was 1268 km s-1)

There were 4 Sab/Sb's with a mean redshift of 1029 km s-1 (Table II group mean was 913 km s-1).

[snip]

I'm having difficulty with these numbers, can you help please?

By referring to Table II, I deduce that "redshift" means V_vir - is that correct?

The 11 galaxies which comprise "ScI's/Seyferts" in Table II (on the line labelled "Sbc and Sc I/I-II and Seyferts") are: "6 ScI's, 3 Sab/Sb Seyferts, and 2 ScII's: NGC 4254, NGC 4303, NGC 4321, NGC 4501, NGC 4535, and NGC 4536 are the ScI's; NGc 4388, NGC 4450, and NGC 4579 are the Sab/Sb Seyferts; NGC 4651 and NGC 4654 are the ScII's" (source); is that correct?

There are 15 "Sab/Sb's" in Table II (on the line labelled "SO-a to Sb") - these are not named in the paper, nor have they been listed in any post in this thread; is that correct?

There are 23 "Sbc/ScIII's" in Table II (on the line labelled "Sbc/ScII-III to IV") - these are not named in the paper, nor have they been listed in any post in this thread; is that correct?

Of the 11 "ScI's/Seyferts", 9 are in Table III, one is among Thanatos' "list of 92" (NGC 4654) and one is not in either list (NGC 4651); is that correct?

[dgruss23]

I'm having difficulty with these numbers, can you help please?

By referring to Table II, I deduce that "redshift" means V_vir - is that correct?

Yes.

The 11 galaxies which comprise "ScI's/Seyferts" in Table II (on the line labelled "Sbc and Sc I/I-II and Seyferts") are: "6 ScI's, 3 Sab/Sb Seyferts, and 2 ScII's: NGC 4254, NGC 4303, NGC 4321, NGC 4501, NGC 4535, and NGC 4536 are the ScI's; NGc 4388, NGC 4450, and NGC 4579 are the Sab/Sb Seyferts; NGC 4651 and NGC 4654 are the ScII's" (source); is that correct?

Yes.

There are 15 "Sab/Sb's" in Table II (on the line labelled "SO-a to Sb") - these are not named in the paper, nor have they been listed in any post in this thread; is that correct?

Yes.

There are 23 "Sbc/ScIII's" in Table II (on the line labelled "Sbc/ScII-III to IV") - these are not named in the paper, nor have they been listed in any post in this thread; is that correct?

Yes.

Of the 11 "ScI's/Seyferts", 9 are in Table III, one is among Thanatos' "list of 92" (NGC 4654) and one is not in either list (NGC 4651); is that correct?

Yes.

[Nereid]

I'll amplify for you Nereid. The point of table III is that the large Sab/Sb galaxies in Virgo have a significantly different redshift distribution from the ScI's. Now you continue to quote that 2000 as if there are 2000 suitable galaxies for this comparison - which as I've already noted to Thanatos is not the case.

To repeat, most of the galaxies in that list of 2000 are ellipticals and most of those are dwarf ellipticals. Many of the 2000 also have redshifts larger than normally accepted for Virgo members (>3000 km s-1). I'll get an exact count if you want.

But you raise the question of the galaxies not selected. So, lets amplify the situation on the galaxies without TFR data.

Going back through the list there were 15 additional galaxies with Hubble T-types between 1.0 and 6.0 that did not have redshift data. Perhaps these galaxies could change the Table III results if we had TFR data? No - they cannot. Why? Every one of these 15 galaxies has an angular diameter of 1.07 arc minutes or less and B magnitudes of 14.30 or fainter. This means that either they are background galaxies or dwarfs. Given the fact that dwarf spirals are rare it is likely that they are background galaxies. In either case they are irrelevant to the Table III sample because they are not large spirals in the Virgo cluster.

In the breakdown I gave Thanatos I identified 124 spirals with redshifts in the standard accepted Virgo cluster range. Of those 124, there were 21 without measured rotational velocities for TFR distances. Could these 21 help to change the Table III result? No, they could not. Here's how they break down: 13 of the 21 are clearly dwarfs based upon angular diameters and magnitudes - regardless of their position within the cluster.

The remaining 8 are dwarfs at the Virgo core distance of ~ 18 Mpc. If you put them at the backside of the cluster (~28 Mpc) they would still be too small to fit into Table III, but they might not be dwarfs.

Recall that 42 of the 124 galaxies had rotational velocities < 100 km s-1 and thus are dwarfs.

[snip]

I'm trying to tie the above with what's in the paper, can you help please?

The paper does not, as far as I can see, have an explicit criterion for 'large spirals'; here's what it says:

In order to evaluate the relationship between mean redshift and morphology in the Virgo Cluster, the LEDA database was searched for all galaxies in Virgo with B-band magnitudes and rotational velocities derived from HI linewidths or optical rotation curves. The sample was restricted to morphological types SO-a to Sc, mean surface brightness in the D₂₅ isophote (bri25 in LEDA) from 22.40 to 24.40 mag arc sec^-2, and log Vrot > 1.89. The sample was supplemented with E and SO galaxies from the Surface Brightness Fluctuation Method study of Tonry et al (2001).

Were there angular diameter* or B-magnitude* criteria you used but did not state? Did you use Vrot as a criterion for selecting for 'large' (vs 'dwarf')?

The 92 galaxies Thanatos listed all (seem to) meet the morphological type, mean surface brightness, and rotational velocity criteria.** Of these, none has a Vrot less than 80 km/s, 4 have a Vrot between 80 and 90, 13 between 90 and 100, and 9 between 100 and 110. This suggests that a large/dwarf selection criterion, based on Vrot, might be around 90 (rather than >100), and that the paper's criterion ("log Vrot > 1.89") was OK.

*logd25 and bt, respectively, in LEDA?
**Yet, somehow, NGC 4651 was excluded.

[Nereid]

Yes.



Yes.



Yes.



Yes.



Yes.

Thanks.

So in order to check the numbers in your post, one would need the names of (another) 56 galaxies (18+15+23), is that correct?

(FYI, I get 1854 vs 1855 km/s as the mean redshift for the Table II ScI's/Seyferts - close enough I suspect).

[dgruss23]

The paper does not, as far as I can see, have an explicit criterion for 'large spirals'; here's what it says:Were there angular diameter* or B-magnitude* criteria you used but did not state? Did you use Vrot as a criterion for selecting for 'large' (vs 'dwarf')?

The criteria was simply the logVrot dividing line of 2.150. In the case of the ScI's in Virgo (and almost all ScI's known) log Vrot is in excess of 2.140, so the comparison in Table III becomes a comparison of galaxies within a similar rotational velocity range.

The 92 galaxies Thanatos listed all (seem to) meet the morphological type, mean surface brightness, and rotational velocity criteria.** Of these, none has a Vrot less than 80 km/s, 4 have a Vrot between 80 and 90, 13 between 90 and 100, and 9 between 100 and 110. This suggests that a large/dwarf selection criterion, based on Vrot, might be around 90 (rather than >100), and that the paper's criterion ("log Vrot > 1.89") was OK.

I gave a detailed breakdown of the Thanatos 92 sample here on Dec 18.

NGC 4651 was excluded.

Thanatos used the list from LEDA assigned to Virgo. NGC 4651 does not have a VCC#, but some papers include NGC 4651 in Virgo studies.

[Nereid]

(my bold)

The criteria was simply the logVrot dividing line of 2.150. In the case of the ScI's in Virgo (and almost all ScI's known) log Vrot is in excess of 2.140, so the comparison in Table III becomes a comparison of galaxies within a similar rotational velocity range.



I gave a detailed breakdown of the Thanatos 92 sample here on Dec 18.



Thanatos used the list from LEDA assigned to Virgo. NGC 4651 does not have a VCC#, but some papers include NGC 4651 in Virgo studies.

Thanks for this; I had somehow overlooked the Dec 18 post

This also goes some way to clarifying another ambiguity: "Virgo" vs "Virgo cluster".

The paper's selection criteria are somewhat vague (my bold):

In order to evaluate the relationship between mean redshift and morphology in the Virgo Cluster, the LEDA database was searched for all galaxies in Virgo with B-band magnitudes and rotational velocities derived from HI linewidths or optical rotation curves. The sample was restricted to morphological types SO-a to Sc, mean surface brightness in the D25 isophote (bri25 in LEDA) from 22.40 to 24.40 mag arc sec-2, and log Vrot > 1.89. The sample was supplemented with E and SO galaxies from the Surface Brightness Fluctuation Method study of Tonry et al (2001).

What was the (unstated?) selection criterion (criteria?) you used, wrt "in the Virgo cluster" vs that used by Thanatos? Specifically, what query (or queries) did you submit to LEDA?

[Nereid]

I have dug further into the discussion of the Virgo Galaxy list first presented by Thanatos (post #2516, p. 84), to look into the "cherry picking" claim. Using the criteria by dgruss23 (post #2642, p. 89), to apply to the Table II galaxy list (not including the Ellipticals) I get the following group of 37 galaxies from Thanatos' list which was obtained from the LEDA database.


Name H type Cz Bri25 Vrot Vvir

NGC4189 6.0 2100 23.30 210.7 2189
NGC4192 2.5 -136 23.62 224.1 -40
NGC4206 4.0 712 23.67 124.8 800
NGC4207 5.9 595 22.65 93.8 667
NGC4212 4.9 -84 22.66 150.8 8
NGC4216 3.0 136 23.23 253.3 224
NGC4237 4.0 865 22.49 140.6 964
NGC4254 5.2 2405 22.57 201.3 2501
NGC4293 0.3 946 23.56 168.8 1061
NGC4294 5.8 359 22.48 101.4 442
NGC4298 5.2 1138 22.78 157.8 1235
NGC4303 4.0 712 23.67 124.8 800
NGC4321 4.0 1578 23.01 223.4 1681
NGC4343 3.0 1012 23.27 162.6 1074
NGC4356 5.8 1135 23.83 107.9 1204
NGC4380 2.3 969 23.48 1529.0 1046
NGC4388 2.8 2522 23.44 180.2 2612
NGC4390 5.0 1103 22.57 82.7 1182
NGC4402 3.3 234 23.54 117.8 326
NGC4450 2.3 1956 23.15 183.0 2067
NGC4457 0.4 887 22.66 99.5 934
NGC4498 6.4 1506 23.02 93.4 1617
NGC4501 3.4 2283 23.04 276.5 2383
NGC4522 5.9 2331 23.30 93.7 2407
NGC4527 4.0 1738 23.23 176.8 2074
NGC4535 5.0 1963 23.44 180.2 2034
NGC4536 4.2 1800 23.47 170.5 1842
NGC4540 6.1 1286 22.68 103.3 1392
NGC4548 3.1 492 23.20 174.4 594
NGC4569 2.4 -239 23.26 176.8 -144
NGC4579 2.8 1517 22.77 266.7 1607
NGC4580 1.6 1039 22.77 117.7 1097
NGC4639 3.5 983 22.91 166.4 1082
NGC4647 5.2 1397 22.91 123.5 1448
NGC4654 5.9 1038 22.72 155.7 1136
NGC4689 4.7 1619 23.08 134.8 1721
NGC4698 1.4 1007 23.06 246.8 1084

The paper states (p.7, last sentence) that the list from LEDA "was supplemented with E and SO galaxies from the Surface Brightness Fluctuation Method study of Tonry et al (2001). From that paper, I get the following 11 galaxies (Type -3 to 0) to supplement the above list.

NGCNGC4379, NGC4459, NGC4468, NGC4476, NGC4526, NGC4531, NGC4550, NGC4620, NGC4638, NGC4754, and I3653.

This brings the total to 48, which is one short of the number in Table II.

So before going further, I have 2 questions:

(1) dgruss23 is the above list the same as used for Table II, save for the 1 galaxy I missed?

(2) Thanatos, do you have any galaxies you feel should be added to this list? If so, could you state which ones, and why they should be included.

TomT

(my bold)

NGC 4343 is one of the 8 Sab/Sb galaxies in Table III.

In post #2642, dgruss23 states (my bold):

If you calculate the TFR distances for the galaxies in the sample you'll find that 14 have TFR distances that put them in the Virgo cluster background. I adopted 30 Mpc as the standard limit - a number that is consistent with what is typically accepted. So these galaxies were not Virgo members:

When I plug the LEDA numbers (above) into the appropriate TD-TFR, I get a distance of 32.8 Mpc, cf 28.1 Mpc in Table III (the V_vir value is the same: 1074). Is this due to a LEDA update?

[Nereid]

The paper does not, as far as I can see, have an explicit criterion for 'large spirals'; here's what it says:Were there angular diameter* or B-magnitude* criteria you used but did not state? Did you use Vrot as a criterion for selecting for 'large' (vs 'dwarf')?

The criteria was simply the logVrot dividing line of 2.150. In the case of the ScI's in Virgo (and almost all ScI's known) log Vrot is in excess of 2.140, so the comparison in Table III becomes a comparison of galaxies within a similar rotational velocity range.

[snip]

NGC 4402 - one of 8 Sab/Sb galaxies listed in Table III - has a V_rot of 117.8 ± 3.5 km/s in LEDA (TomT and Thanatos' posts have the same value), so should not be included in Table III, by the above criterion.

Is this due to a LEDA update?

[dgruss23]

The paper's selection criteria are somewhat vague (my bold):What was the (unstated?) selection criterion (criteria?) you used, wrt "in the Virgo cluster" vs that used by Thanatos? Specifically, what query (or queries) did you submit to LEDA?

Sandage et al provided the list of spiral galaxies from the complete Virgo cluster sample. I used their list and searched the LEDA database for the galaxies that met the criteria stated in the paper as the starting point. Since Sandage et al were working from the complete VCC and since I'm familiar with the other papers that have applied the TFR to Virgo, I didn't see any need to SQL HyperLeda.

However, you seem capable of scouring that VCC list for an example that was missed. You can then plug that in with the rest of the sample to see if that changes the numbers. I've already done that and summarized the results in several posts in response to you and Thanatos. See here .

[dgruss23]

(my bold)

NGC 4343 is one of the 8 Sab/Sb galaxies in Table III.

When I plug the LEDA numbers (above) into the appropriate TD-TFR, I get a distance of 32.8 Mpc, cf 28.1 Mpc in Table III (the V_vir value is the same: 1074).

Actually you get a distance modulus of 32.80 which converts to a distance of 36.3 Mpc.

Is this due to a LEDA update?

Yes, its why I've stopped using LEDA as a source for rotational velocities and switched to the K-band TFR using 2MASS Ks-band magnitudes. It became quite frustrating for me to download a set of data, and then the next time I checked the data I get different numbers.

You indicated some of that frustration with the redshifts of the galaxies.

NGC 4343 had a corrected B-magnitude of 12.36 when I originally wrote the paper, now it's 12.88.

Using the K-band magnitude from 2MASS and the current rotational velocity in HyperLeda, the distance modulus is 31.89 which converts to a distances of 23.9 Mpc and PV72 = -599 km s-1.

NGC 4402 - one of 8 Sab/Sb galaxies listed in Table III - has a Vrot of 117.8 ± 3.5 km/s in LEDA (TomT and Thanatos' posts have the same value), so should not be included in Table III, by the above criterion.

Is this due to a LEDA update?

The rotational velocity was 146 km s-1. So yes, LEDA update.

[VanderL]

I may have missed it, but it seems that after Dgruss23 explained all the details, there is nothing in Nereid's selection bias investigation (or any other challenger) that would have a strong impact on the conclusions of the Russell paper. As far as I can see there's not a single reason not to accept Russell's conclusions, except of course the obvious reason that it's an ATM conclusion.

Imo, only studies based on more (reliable) data from the galactic surveys can either strengthen the conclusion, or in showing a selection bias, overturn the findings. I think there is every reason to accept the possibility of intrinsic redshift based on this paper.

Cheers.

[Jerry]

I may have missed it, but it seems that after Dgruss23 explained all the details, there is nothing in Nereid's selection bias investigation (or any other challenger) that would have a strong impact on the conclusions of the Russell paper. As far as I can see there's not a single reason not to accept Russell's conclusions, except of course the obvious reason that it's an ATM conclusion.

That is reason enough. Look how many men of science must be wrong if there is some dark thingy contributing to redshift. Dark stuff is reserved for mainstream use only.

[VanderL]

I may have missed it, but it seems that after Dgruss23 explained all the details, there is nothing in Nereid's selection bias investigation (or any other challenger) that would have a strong impact on the conclusions of the Russell paper. As far as I can see there's not a single reason not to accept Russell's conclusions, except of course the obvious reason that it's an ATM conclusion.

That is reason enough.

Then I hope the challengers are willing to acknowledge this, so we could move on to examine different ways in verifying/falsifying this result.

Look how many men of science must be wrong if there is some dark thingy contributing to redshift. Dark stuff is reserved for mainstream use only.

I don't think scientists are a priori unwilling to change their views (exactly the reason we have so much dark stuff in the first place) as long as the evidence is solid and reproducible/testable (or at least irrefutable).

The problem with the redshift discussion is that some false arguments have been raised in order to dismiss it (some have been shown to be false, but I list them anyway):

1. Intrinsic redshift excludes a Big Bang cosmology.
2. Arp was shown wrong decades ago, so the whole idea must be ludicrous.
3. Lack of a mechanism means intrinsic redshift must be wrong.
4. Extraordinary claims require extraordinary evidence.
5. Because only a few scientists publish on intrinsic redshift it must be considered "fringe" science at best.
6. Using only observational evidence is not science.

The work done by Arp, Bell, Burbidge, Russell and other proponents is scientific in approach and can be tested and falsified. Some tests are:

1. Expanding the number of galaxies included in Russell's paper and see if the conclusions hold.
2. Proper motion studies to falsify the quasar ejection hypothesis.
3. Detailed spectral analyses to investigate possible bridges between high and low redshift objects.

Cheers.

[TomT]

The problem with the redshift discussion is that some false arguments have been raised in order to dismiss it (some have been shown to be false, but I list them anyway):

1. Intrinsic redshift excludes a Big Bang cosmology.
2. Arp was shown wrong decades ago, so the whole idea must be ludicrous.
3. Lack of a mechanism means intrinsic redshift must be wrong.
4. Extraordinary claims require extraordinary evidence.
5. Because only a few scientists publish on intrinsic redshift it must be considered "fringe" science at best.
6. Using only observational evidence is not science.

The work done by Arp, Bell, Burbidge, Russell and other proponents is scientific in approach and can be tested and falsified. Some tests are:

1. Expanding the number of galaxies included in Russell's paper and see if the conclusions hold.
2. Proper motion studies to falsify the quasar ejection hypothesis.
3. Detailed spectral analyses to investigate possible bridges between high and low redshift objects.

Cheers.

The above are all good and fair points. I would point out that the Russell paper we have been discussing, has other sections that present data for over 150 more galaxies that we haven't even addressed yet.
TomT

[VanderL]

I would point out that the Russell paper we have been discussing, has other sections that present data for over 150 more galaxies that we haven't even addressed yet.
TomT

And it seems they are going to stay that way.

Cheers.

[Cougar]

I may have missed it, but it seems that after Dgruss23 explained all the details, there is nothing in Nereid's selection bias investigation (or any other challenger) that would have a strong impact on the conclusions of the Russell paper. As far as I can see there's not a single reason not to accept Russell's conclusions...

Yes, you missed the numerous reasons to be skeptical of Russell's conclusions.

I think there is every reason to accept the possibility of intrinsic redshift based on this paper.

"Possibility" is one thing. Actuality is quite another.

[Cougar]

As far as I can see there's not a single reason not to accept Russell's conclusions, except of course the obvious reason that it's an ATM conclusion.

That is reason enough.

Then I hope the challengers are willing to acknowledge this...

That's ridiculous. How many of the thousands of posts in this thread state that they do not accept Russell's conclusions based solely on the fact that the conclusions are against the mainstream?

I don't think scientists are a priori unwilling to change their views... as long as the evidence is solid and reproducible/testable (or at least irrefutable).

Goodness, what's gotten over you in making this sensible statement?

The problem with the redshift discussion is that some false arguments have been raised in order to dismiss it (some have been shown to be false, but I list them anyway):
2. Arp was shown wrong decades ago, so the whole idea must be ludicrous.

AFAIK, Arp's position decades ago is pretty much the same as his current position. If he was wrong then, how is it a false argument that the same old argument is still wrong?... particularly when an order of magnitude increase in technological and detection capability has not been accompanied by ANY increase in the evidentiary certainty of Arp's position.

3. Lack of a mechanism means intrinsic redshift must be wrong.

I think dgruss has made it clear that this argument is not necessarily valid. But lack of a mechanism is certainly a major drawback to the Arpian hypothesis that is based on evidence that is NOT solid.

4. Extraordinary claims require extraordinary evidence.

This is no false argument. It's a perfectly reasonable expectation.

5. Because only a few scientists publish on intrinsic redshift it must be considered "fringe" science at best.

Well, it IS fringe science. That doesn't mean it's necessarily wrong, but it does mean that most people can justifiably ignore it -- unless and until it comes up with enough compelling evidence to move it out of the fringe.

6. Using only observational evidence is not science.

It is observed that the Sun rises and sets. This does not mean the Sun revolves around the Earth.

[dgruss23]

Yes, you missed the numerous reasons to be skeptical of Russell's conclusions.

VanderL's point is that while many reasons to be skeptical have been raised, those reasons have been rebutted by myself.

[Cougar]

VanderL's point is that while many reasons to be skeptical have been raised, those reasons have been rebutted by myself.

Well, you've responded to most of the criticisms, but I wouldn't say you've actually refuted all of them. To take just one example, the paper's sample size has been criticized. You have explained that your sample is restricted because of the scarcity of data available within the range and types you have selected. This explains why your sample is not larger, but it does not really "rebut" the fact that the strength of your conclusion is weakened due to small-number statistics.

[VanderL]

Well, you've responded to most of the criticisms, but I wouldn't say you've actually refuted all of them. To take just one example, the paper's sample size has been criticized. You have explained that your sample is restricted because of the scarcity of data available within the range and types you have selected. This explains why your sample is not larger, but it does not really "rebut" the fact that the strength of your conclusion is weakened due to small-number statistics.

Incorrect criticism, you can only research stuff that's available, look here and see how science works; the results from small numbers can only get better and better. Btw 150 galaxies isn't really small, Perlmutter's SNe 1a sample that gave us an accelerated Universe are at the moment also some 150. It's your frame of mind that wants to disregard the Russell paper, there's nothing wrong with the science.

Cheers.

[dgruss23]

Well, you've responded to most of the criticisms, but I wouldn't say you've actually refuted all of them. To take just one example, the paper's sample size has been criticized. You have explained that your sample is restricted because of the scarcity of data available within the range and types you have selected. This explains why your sample is not larger, but it does not really "rebut" the fact that the strength of your conclusion is weakened due to small-number statistics.

The number of ScI's actually present in the Virgo cluster is just a bit out of my control. The point remains that all the ScI's that are present have positive redshift discrepancies (peculiar motions in standard views). The sample is not so small that it can be said the result is not unusual.

However, you seem to be forgetting that there are entire sections of the paper not discussed as well as the follow-up papers.

And what would be the other examples?

[dgruss23]

Speaking of sample size, I've always found this paper interesting because the researchers determined the Hubble constant from 2 galaxies, added a third from their previous study, and then added 6 from the Hubble Key Project final sample. At the same time this paper came out I recieved a referee report in which the referee told me that my sample of ~250 galaxies was too small to make any comments on the value of the Hubble Constant.

[Ari Jokimaki]

Speaking of sample size, I've always found this paper interesting because the researchers determined the Hubble constant from 2 galaxies, added a third from their previous study, and then added 6 from the Hubble Key Project final sample. At the same time this paper came out I recieved a referee report in which the referee told me that my sample of ~250 galaxies was too small to make any comments on the value of the Hubble Constant.

It also takes far less than 250 distant too dim supernovae to change radically our view of the universe. It looks like sufficient sample size is quite relative concept.

[Cougar]

And what would be the other examples?

There were a number of criticisms back on Page 73 when astro_uk checked in – I’m not sure these were “answered” sufficiently. For example....

• Further [Tully-Fisher] is only really useful in cases where you have very similar galaxies.
  
• Several recent papers have investigated the TF and found that it varies considerably between galaxy types and over time. For example in this paper http://arxiv.org/pdf/astro-ph/0603042 looking at the TF at z=1 they find that the TF is shifted upwards in magnitude, reflecting the extra star formation ongoing at that point . Another recent paper http://arxiv.org/pdf/astro-ph/0609076 investigating the TF for S0 galaxies found that the TF relation is offset to lower Magnitudes, because S0s are not forming stars and hence have faded since they were.
  
• The important point is that the TF depends on the star formation rate in a galaxy, if you select galaxies that are not forming stars at a similar rate you can get into trouble. Also star formation is related to position in a cluster (see below), if you aren't extremely careful about how you select your galaxies you can get really screwed up by picking galaxies that are not comparable.
• [There are] very few spirals in clusters (such as Virgo), this is because the gas in them is stripped out during the fall into the cluster. These spirals become S0s as they fall into the cluster. This is very important because it means that the spirals that Russell assumes are in Virgo are almost certainly not, they form a shell around the main cluster. Hence because Virgo has a fairly large virial radius > Mpc, it is not fair to assume they are all located in the cluster.... But it gets even worse, there are large filaments feeding into Virgo, http://www.ifa.hawaii.edu/~tully/, in these filaments are galaxies that are streaming into Virgo at a significant speed. So the assumption that you make that if you look at enough spirals around Virgo it will even out so it seems like they are all in the centre wont hold.

There’s also a key point that Nereid made. astro_uk summed it up best –

“It is strange that the supposedly strong correlations seem to get weaker with more data, exactly as you would expect if they were due to statistical noise.”

Then there was Astronomer, who had a pretty good criticism of the whole Arpian enterprise.

[TomT]

There were a number of criticisms back on Page 73 when astro_uk checked in – I’m not sure these were “answered” sufficiently. For example....

• Further [Tully-Fisher] is only really useful in cases where you have very similar galaxies.
  
• Several recent papers have investigated the TF and found that it varies considerably between galaxy types and over time. For example in this paper http://arxiv.org/pdf/astro-ph/0603042 looking at the TF at z=1 they find that the TF is shifted upwards in magnitude, reflecting the extra star formation ongoing at that point . Another recent paper http://arxiv.org/pdf/astro-ph/0609076 investigating the TF for S0 galaxies found that the TF relation is offset to lower Magnitudes, because S0s are not forming stars and hence have faded since they were.
  
• The important point is that the TF depends on the star formation rate in a galaxy, if you select galaxies that are not forming stars at a similar rate you can get into trouble. Also star formation is related to position in a cluster (see below), if you aren't extremely careful about how you select your galaxies you can get really screwed up by picking galaxies that are not comparable.
• [There are] very few spirals in clusters (such as Virgo), this is because the gas in them is stripped out during the fall into the cluster. These spirals become S0s as they fall into the cluster. This is very important because it means that the spirals that Russell assumes are in Virgo are almost certainly not, they form a shell around the main cluster. Hence because Virgo has a fairly large virial radius > Mpc, it is not fair to assume they are all located in the cluster.... But it gets even worse, there are large filaments feeding into Virgo, http://www.ifa.hawaii.edu/~tully/, in these filaments are galaxies that are streaming into Virgo at a significant speed. So the assumption that you make that if you look at enough spirals around Virgo it will even out so it seems like they are all in the centre wont hold.

Hi Cougar,
The above points were discussed with astro_uk in posts 2215, 2217, 2220, 2224, 2240, 2242, 2243, 2244, 2249, 2250, 2254.
I believe his comment in 2249 showed that he conceded that there is "something there" that Russell's paper points out.
TomT

[dgruss23]

There were a number of criticisms back on Page 73 when astro_uk checked in – I’m not sure these were “answered” sufficiently. For example....

• Further [Tully-Fisher] is only really useful in cases where you have very similar galaxies.

Like restricting the sample to ScI galaxies? Like correcting the Tully-Fisher relation for the type effect? ( Type Dependence

• Several recent papers have investigated the TF and found that it varies considerably between galaxy types and over time. For example in this paper http://arxiv.org/pdf/astro-ph/0603042 looking at the TF at z=1 they find that the TF is shifted upwards in magnitude, reflecting the extra star formation ongoing at that point . Another recent paper http://arxiv.org/pdf/astro-ph/0609076 investigating the TF for S0 galaxies found that the TF relation is offset to lower Magnitudes, because S0s are not forming stars and hence have faded since they were.

Two things here. First, most of the analysis (the stuff not even discussed yet) is restricted to ScI group galaxies. In fact SO galaxies were not used. Second, the observed scatter of the TFR is very small for the local samples we're talking about (where "local" is within 200 Mpc). Galaxies at z=1 simply are not relevant to the results we're discussing. The results on the high z TF samples are inconsistent in their results. Some studies show very little luminosity evolution while others show a large luminosity evolution.

The important point is that the TF depends on the star formation rate in a galaxy, if you select galaxies that are not forming stars at a similar rate you can get into trouble.

When you have redshift independent distances for calibration, it turns out that there is very little scatter in the TFR. In addition it also depends upon what wavelenth you look at. In the B-band star formation effects are larger (yet the Type dependent TFR significantly corrects for this because the narrow arms of ScI galaxies are well defined by current star formation), but in the K-band the type effect is much smaller because the underlying older population dominates the light.

Also star formation is related to position in a cluster (see below), if you aren't extremely careful about how you select your galaxies you can get really screwed up by picking galaxies that are not comparable.
[There are] very few spirals in clusters (such as Virgo), this is because the gas in them is stripped out during the fall into the cluster. These spirals become S0s as they fall into the cluster. This is very important because it means that the spirals that Russell assumes are in Virgo are almost certainly not, they form a shell around the main cluster.

Irrelevant for several reasons. First, if you look at the distance distribution of the spirals you'll see that the ScI's match the distance distribution of the other galaxy types. No "assumption" was made. The distances were calculated with the TFR. In fact, that was the whole point of the TFR analysis. Arp and others had previously made assumptions that they were members or that they were on the backside of the cluster (based upon the large redshifts). But the Cepheid and TFR distances show that they are at the distance of the cluster.

Second, as for the "shell" concept. Can anybody explain why the ScI's are on the receding side of the shell while the Sab/Sb's are on the approaching side of the shell? Other than saying its an "accident" there is no reason to expect the spirals to be distributed by morphology in that fashion.

Hence because Virgo has a fairly large virial radius > Mpc, it is not fair to assume they are all located in the cluster.... But it gets even worse, there are large filaments feeding into Virgo, http://www.ifa.hawaii.edu/~tully/, in these filaments are galaxies that are streaming into Virgo at a significant speed. So the assumption that you make that if you look at enough spirals around Virgo it will even out so it seems like they are all in the centre wont hold.

Nobody made that assumption. Distance were calculated ... and in the mean they fall at the cluster center. And most of them fall pretty close to the core distance. But the ScI's are not in filaments. If you look at their locations, they're scattered around the cluster both by coordinate and by distance. These concepts of shells and infalling filaments don't explain it.

There’s also a key point that Nereid made. astro_uk summed it up best –

“It is strange that the supposedly strong correlations seem to get weaker with more data, exactly as you would expect if they were due to statistical noise.”

Are we talking about my papers or quasars now? If we were to accept Nereid's point as correct (which it likely isn't because incorrect assumptions are often made with these studies that use the larger data sets), the point has nothing to do with spiral galaxies - for which increased data has only led to a stronger case.

Then there was Astronomer, who had a pretty good criticism of the whole Arpian enterprise.

Pretty good criticism??? I think ToSeek summed it up best.