Nordic-Baltic Astronomy Days 2026

Session

27-C2: Galaxies

We-08C

27 May 2026, 15:00

Room C

Description

Chair: Sabine König

289. Galaxy Unsupervised Learning classification combining UMAP and clustering algorithms

Luis Suelves (Tartu Observatory, University of Tartu)

27/05/2026, 15:00

Oral

Unsupervised Machine Learning can create classifications by learning from data features and has the capacity to process the vast number of galaxies observed by contemporary large sky telescopes. We designed an Unsupervised ML technique that performs a dimensionality reduction with UMAP and then applies clustering methods such as GMM and HDBSCAN to the resulting 2D embedding. It was implemented...

290. eSCALE: Mapping galaxy groups at low redshift with S-PLUS and eROSITA surveys

Lia Doubrawa (Universiy of Helsinki)

27/05/2026, 15:15

Oral

Galaxy clusters and groups are powerful tools for investigating the properties of the Universe. However, the identification of low-redshift X-ray groups remains challenging, requiring deep optical catalogs with reliable redshift estimates over large sky areas. In this work, we aim to detect and characterize galaxy groups through their outskirts by applying an optimized technique that enables...

291. Stellar cores live long and prosper in cuspy dark matter halos

Jenni Häkkinen (University of Helsinki)

27/05/2026, 15:30

Oral

The existence of cuspy or cored centers of dark matter halos is a crucial discriminant between different dark matter models. It has recently been claimed that perfectly cored stellar systems cannot survive inside cuspy dark matter halos, which would make the observation of stellar cores in ultra-faint dwarf galaxies, where dark matter cores cannot form through baryonic processes, a direct...

292. Milky Way analogue galaxies in the J-PAS sky survey

Teet Kuutma (Tartu Observatory of the University of Tartu)

27/05/2026, 15:45

Oral

The position of the Earth in the Milky Way galaxy allows detailed study of stellar and gas processes inside the Galaxy. On the other hand, Earth's position inside the Milky Way disk inhibits vision of the entirety of the Galaxy, complicating studies of the Galaxy in its entirety. One solution is to study stellar populations of other galaxies with similar properties to the Milky Way. These...

293. Age and metallicity dependency in measuring distances of early-type galaxies using planetary nebula luminosity function (PNLF) with VLT-MUSE

Azlizan Adhyaqsa Soemitro (Leibniz-Intitut für Astrophysik Potsdam (AIP))

27/05/2026, 16:00

Oral

Planetary nebulae (PNe) are post-AGB shells around stars from main sequence progenitors of 1- 8 solar masses. PNe typically emit a strong emission line of [OIII]5007, making them observable in distant galaxies. Narrow band [OIII]5007 photometry of galaxies has been used to identify the PN candidates within and construct the corresponding planetary nebula luminosity function (PNLF). With the...