meeting 2025 04 25 n57 - JacobPilawa/TriaxSchwarzschild_wiki_5 GitHub Wiki

Context

Collating some information on the H15 environment here.
I'm having a hard time accessing the SuperCOSMOS Science Archive database which was used in Bravo-Alfaro+09 to study the environemnt of H15. Yesterday, I was having issues connecting to the SQL database, but today I can't even get the error message to load. Instead, after querying at a specific set of coordinates, the page seems to sit in a constant "loading" phase.
In the meantime, I found a separate, earlier paper which at least catalogs the velocities of a number of galaxies toward A85 and have been playing around with that data a bit. This is a bit less annotated so still trying to figure out what each of the columns actually mean.
In the meantime, here's a few diagnostics to confirm I can reproduce what the author's claim:
- First, here's a quick comparison of their full dataset on the sky vs. what they identify as the memebrs of A85. I've included a red star where H15 is according to Simbad, and I have highlighted the 10 nearest neighbors to that point

Full Data	A85 Members Only
[images/250425/all_objects.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_5/wiki/[[images/250425/A85_galaxies_only.png)

The way they determine membership is via slicing velocities. I am able to get their exact number of members (305) by slicing in the way they describe:

All Velocities	A85 Velocities Only
[images/250425/all_velocities.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_5/wiki/[[images/250425/a85_velocities.png)

Working on getting nu10 now, need to find magnitude calibration information for this instrument. Coming soon...

I've copied the information from yesterday's page to here so it's a bit more concentrated in this bullet:
H15 Information:
- N_{HDC} estimates:
  - 367 members
  - 280 members but over a limited velocity range
  - A more recent work which is finding something like ~520 cluster members
    - This work also quotes an M200 value of ~6.1e14 Msun, and because this work has both a cluster membership and an M200 mass, I'm leaning toward quoting these values in our final environmental plot.
- Halo Mass Estimates
  - Looking for a good way to obtain Mhalo here since the Crook+07 method is quite specific to that work. For now I'm assembling some various measurements that we could use/adapt to our case:
    - ~8e14 Msun for M500 from x-ray luminosity/temperature relations
    - ~4e14 Msun for Mdyn at the extent of their data (~10 arcmin) also from x-ray temperature profile

As mentioned above, I was able to get the SuperCOSMOS Science Archive Working, and I was able to get some velocity data from a subset of the catalog used in Bravo-Alfaro+09 (it seems like the Andernach work that is referenced never got published/a public catalog is not available for all of the velocity data, so I instead grabbed the Duret+98 velocity catalog)
I've started to try to catalog match between sources here, and here are two quick plots showing the full catalogs. The blue points here are the results from the SuperCOSMOS Science Archive Query (all objects within 50 arcmin of H15), and the red points are the points with velocity information from Duret+1998. They are slightly offset from each other due to being at slightly different RA/dec, but the matching procedure will likely use minimum angular separations to determine matches.

Full Catalogs	Zoomed to H15
[images/250428/full_catalogs.png]]](/JacobPilawa/TriaxSchwarzschild_wiki_5/wiki/[[images/250428/full_catalogs_centered.png)

Here's an identical version of the "Zoomed" plot, but made a bit larger to see the points being matched.

Large Version
images/250428/full_catalogs_centered_large.png

Trying to move to matching galaxies between catalogs and finding the nearest 10, currently landing on something like this:

Matched
images/250428/top10_neighbors.png

Just adding some work in progress, but I slightly cleaned up this version of the plot:

Cleaned Matched Plot
images/250428/neighbors_used_to_calc.png

Here's the actual data associateed with the nearest neighbors (H15 is excluded since we are not counting it in the nu10 calculation):
- I'm assuming H15 is at D_A = 222.3 Mpc, which implies D_L = 247 Mpc. I'm assuming a solar I band luminosity of 4.07 from Blanton Roweis+07.
- The separation to the 10th neighbor is ~180 arcsec, which corresponds to a distance of ~0.195 Mpc which is used as the r10 value in the nu10 calculation. The numerator is the sum of 10^(-0.4(M_I - 4.07)).

The resulting nu10 I get for this is thus ~2.96e12. We've been reporting nu10/nubar, with nubar=2.8e8, and thus our nu10/nubar = 10561 for this galaxy. The point added to the environment plot would thus be:
- Note I'm using the 367 cluster member value from Bravo-Alfaro+09 for the N_{HDC} number.
- I've temporarily used the M200 value for Mhalo for H15, from here, also quoted above under the Nhdc measurements
- Note that this uses the I band data, whereas all the other nu10 calculations are done in K-band. I've also made no cuts on the sources here (based on photometry), whereas we had imposed a cutoff of M_K < -23.0 in our alternative nu10 calculation. Because the photometry here is much shallower, I think we should just compute nu10 with what we have and add a clarification note in the text.

Updated Env w H15
images/250428/250422_fiducial_lineary_with_H15.png
images/250428/250422_fiducial_black_and_red_with_H15.png

Just trouble shooting things here to ensure I am getting the correct objects/they are what they say they are. So to do this, I ran some queries on the mathced coordinates to obtain the galaxy names and references for these nearest galaxies.
- These objects were obtained by querying SIMBAD at the matched coordinates and finding the closest object marked as a galaxy to these coordinates.
- I've verified that these objects are all in fact classified as galaxies (and their classifications from the original spectroscopic survey source also classify them as galaxies).

One question Chung-Pei had asked at the end of last week was what are the magnitude limits for the surveys targetting A85, and how does that compare to our calculation of nu10. I went down a rabbit hole on some of the old papers and exact values were a bit hard to find, but in Habas+18 (a very recent spectroscopic study of the cluster), the magntiude limit for their VIMOS data is -19.0 < M_r < -16.5, corresponding to a mass of 10^(7.5) < M < 10^(10) [m<20.5 SDSS limiting magnitude is their claim]
- The earlier (Duret+98) works seem to quote completeness limits of b_J < 21.3 for a 1 degree radius and 95% complete at b_J < 19.75 over a 5 deg by 5 deg FOV.