| Full text | |
| Author(s): |
de Souza, R. S.
[1, 2, 3]
;
Dantas, M. L. L.
[2]
;
Costa-Duarte, M. V.
[2, 4]
;
Feigelson, E. D.
[5, 6]
;
Killedar, M.
[7]
;
Lablanche, P. -Y.
[8, 9]
;
Vilalta, R.
[8, 10]
;
Krone-Martins, A.
[11]
;
Beck, R.
[12]
;
Gieseke, F.
[13]
Total Authors: 10
|
| Affiliation: Show less - | [1] MTA Eotvos Univ, EIRSA Lendulet Astrophys Res Grp, H-1117 Budapest - Hungary
[2] Univ Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, R do Matao 1226, BR-05508090 Sao Paulo - Brazil
[3] Univ North Carolina Chapel Hill, Dept Phys & Astron, Chapel Hill, NC 27599 - USA
[4] Leiden Univ, Leiden Observ, Niels Bohrweg 2, NL-2333 CA Leiden - Netherlands
[5] Penn State Univ, Dept Astron & Astrostat, Davey Lab 525, University Pk, PA 16802 - USA
[6] Penn State Univ, Ctr Astrostat, Davey Lab 525, University Pk, PA 16802 - USA
[7] Burnet Inst, 85 Commercial Rd, Melbourne, Vic 3004 - Australia
[8] African Inst Math Sci, 6 Melrose Rd, ZA-7945 Cape Town - South Africa
[9] Stellenbosch Univ, ZA-7602 Matieland - South Africa
[10] Univ Houston, Dept Comp Sci, 4800 Calhoun Rd, Houston, TX 77204 - USA
[11] Univ Lisbon, CENTRA SIM, Fac Ciencias, Ed C8, P-1749016 Lisbon - Portugal
[12] Eotvos Lorand Univ, Dept Phys Complex Syst, H-1117 Budapest - Hungary
[13] Radboud Univ Nijmegen, Toernooiveld 212, NL-6525 EC Nijmegen - Netherlands
Total Affiliations: 13
|
| Document type: | Journal article |
| Source: | Monthly Notices of the Royal Astronomical Society; v. 472, n. 3, p. 2808-2822, DEC 2017. |
| Web of Science Citations: | 7 |
| Abstract | |
We invoke a Gaussian mixture model (GMM) to jointly analyse two traditional emission-line classification schemes of galaxy ionization sources: the Baldwin-Phillips-Terlevich (BPT) and W-H alpha versus {[}N-II]/H alpha (WHAN) diagrams, using spectroscopic data from the Sloan Digital Sky Survey Data Release 7 and SEAGal/STARLIGHT data sets. We apply a GMM to empirically define classes of galaxies in a three-dimensional space spanned by the log {[}O (III)]/H beta, log {[}N-II]/H alpha and log EW(H alpha) optical parameters. The best-fitting GMM based on several statistical criteria suggests a solution around four Gaussian components (GCs), which are capable to explain up to 97 per cent of the data variance. Using elements of information theory, we compare each GC to their respective astronomical counterpart. GC1 and GC4 are associated with star-forming galaxies, suggesting the need to define a new starburst subgroup. GC2 is associated with BPT's active galactic nuclei (AGN) class and WHAN's weak AGN class. GC3 is associated with BPT's composite class and WHAN's strong AGN class. Conversely, there is no statistical evidence-based on four GCs-for the existence of a Seyfert/lowionization nuclear emission-line region (LINER) dichotomy in our sample. Notwithstanding, the inclusion of an additional GC5 unravels it. The GC5 appears associated with the LINER and passive galaxies on the BPT and WHAN diagrams, respectively. This indicates that if the Seyfert/LINER dichotomy is there, it does not account significantly to the global data variance and may be overlooked by standard metrics of goodness of fit. Subtleties aside, we demonstrate the potential of our methodology to recover/unravel different objects inside the wilderness of astronomical data sets, without lacking the ability to convey physically interpretable results. The probabilistic classifications from the GMM analysis are publicly available within the COINtoolbox at https://cointoolbox. github. io/GMM\_ Catalogue/. (AU) | |
| FAPESP's process: | 14/18632-6 - The cosmic web described by superclusters of galaxies |
| Grantee: | Marcus Vinícius Costa Duarte |
| Support Opportunities: | Scholarships in Brazil - Post-Doctoral |
| FAPESP's process: | 16/13470-3 - The drivers of star-formation activity in galaxy clusters |
| Grantee: | Laerte Sodré Junior |
| Support Opportunities: | Research Grants - Visiting Researcher Grant - International |
| FAPESP's process: | 16/05254-9 - Investigating galaxy clusters in the photometric redshift space |
| Grantee: | Marcus Vinícius Costa Duarte |
| Support Opportunities: | Scholarships abroad - Research Internship - Post-doctor |
| FAPESP's process: | 12/00800-4 - The 3-D universe: astrophysics with large galaxy surveys |
| Grantee: | Laerte Sodré Junior |
| Support Opportunities: | Research Projects - Thematic Grants |