Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The conformity of HI galaxies in ALFALFA-SDSS sample   The conformity effect, indicating the evolution of a galaxy is related to its
surrounding neighbour galaxies as far as a few Mpc, is an interesting
phenomenon in the modeling of galaxy and evolution. Here we study the
conformity effect of HI galaxies in a matched galaxy sample between SDSS DR7
and ALFALFA surveys. By checking the probability difference for the detected HI
galaxies as a function of distance around a normal or an HI galaxy, we find
that this effect is significant out to 5 Mpc. It also shows a dependence on the
stellar mass of galaxies, with the strength the strongest in the stellar mass
range of 10^10~10^10.5. However, when the sample is confined to central
galaxies in groups with virial radii smaller than 1 Mpc, the 1-halo conformity
signal is still evident, while the 2-halo conformity signal is reduced to a
very weak amplitude. Our results confirm the previous study in the optical band
that the 2-halo term is possibly caused by the bias effect in the sample
selection. Furthermore, we confirm the existence of the 1-halo conformity
discovered in the optical and radio band in previous lectures. Our results
provide another viewpoint of the conformity effect and hope to shed the light
on the co-evolution of the galaxies and their neighbours in the current galaxy
formation models.

30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
13
The categories of this paper are: quant-ph
36
The categories of this paper are: cmp-lg
5
The categories of this paper are: gr-qc
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
21
The categories of this paper are: adap-org
26
The categories of this paper are: bayes-an
15
The categories of this paper are: nucl-ex
9
The categories of this paper are: nlin
24
The categories of this paper are: dg-ga
33
The categories of this paper are: plasm-ph
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom