I want to do a research about some properties of galaxies which are merging. Thus, a large sample of merging galaxies is required.
Are there some fields can help us to identify the merging galaxies so that we can extra the information of a large sample galaxies?
It really depends on what definition you would like to apply, i.e., what do you mean by mergers?
For instance: distance to near neighbors, morphological disturbance, modified internal properties (i.e. SFR). Any of these could be computed and used to define a merger sample.
Sincerely thank you for your replying.
The science goal of our work is to study the emission line properties, e.g., H/alpha, of galaxies which are merging. Thus, we prefer the modified internal properties as the definition of merging.
The two scripts shown in example scripts of Sunlink is valuable. Especially, the numMergers script give a good template for me to do study about major merger. Thus, I sincerely hope you don't mind a stupid detail question as following.
In this calculation, if I haven't misunderstood the script of 'numMergers', the "NextProgenitorID" is not calculated in order. "fpIndex" is calculated in the order(1,2,3,4,5...), while the order of "npIndex" is complex (1595,1670,1692,-1).
the question is,for a given "FirstProgenitorID",whether the "NextProgenitorID" has been fully covered before it become "-1"?
If yes, why the order of "NextProgenitorID" is designed as such way? If no, Is there a problem in the value of "numMergers" since there are other possibilities which are not involved.
The NextProgenitorID is explained in the picture here. For example, the red arrow pointing from (1) to (5) is a NextProgenitorID link. But there is no such link from (2), so this would have a value of -1.
The full tree is ordered "depth first", which means, as you say, that the FirstProgenitorID will be 'in order', while the NextProgenitorID will in general point elsewhere and this depends on the depth and complexity of the tree, so it will not be in order.