Tracing the Giant Outer Halo of the Mysterious Massive Disk Galaxy M104. I. Photometry of the Extended Globular Cluster Systems

Abstract M104 (NGC 4594, the Sombrero galaxy) is a mysterious massive early-type galaxy that shows a dominant bulge and a prominent disk. However, the presence of a halo in M104 has been elusive, and it is not yet known how M104 has acquired such a peculiar structure. Using wide (∼2 deg 2 ) and deep...

Full description

Saved in:
Bibliographic Details
Published in:The Astrophysical journal 2022-11, Vol.939 (2), p.74
Main Authors: Kang, Jisu, Lee, Myung Gyoon, Jang, In Sung, Ko, Youkyung, Sohn, Jubee, Hwang, Narae, Park, Byeong-Gon
Format: Article
Language:English
Subjects:
Astrophysics
Clumps
Disk galaxies
Dwarf galaxies
Early-type galaxies
Elliptical galaxies
Galaxy evolution
Globular clusters
Globular star clusters
Lenticular galaxies
Metals
Ponds
Stars & galaxies
Subpopulations
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Abstract M104 (NGC 4594, the Sombrero galaxy) is a mysterious massive early-type galaxy that shows a dominant bulge and a prominent disk. However, the presence of a halo in M104 has been elusive, and it is not yet known how M104 has acquired such a peculiar structure. Using wide (∼2 deg 2 ) and deep ugi images of M104 obtained with the CFHT/MegaCam, we detect a large number of globular clusters (GCs) found out to R ≈ 35 ′ (∼100 kpc). The color distribution of these GCs shows two subpopulations: a blue (metal-poor) system and a red (metal-rich) system. The total number of GCs is estimated to be N GC = 1610 ± 30 and the specific frequency to be S N = 1.8 ± 0.1. The radial number density profile of the GCs is steep in the inner region at R < 20 ′ and becomes shallow in the outer region at 20 ′ < R < 35 ′ . The outer region is dominated by blue GCs and is extended out to R ≈ 35 ′ . This shows clearly the existence of a giant metal-poor halo in M104. The inner region is composed of a bulge hosting a disk, corresponding to a metal-rich halo as seen in early-type galaxies. At least two clumps of blue GCs are found in the outer region. One clump is overlapped with a faint stellar stream located in the southwest, indicating that it may be a remnant of a disrupted dwarf galaxy. Our results imply that the metal-rich inner halo of M104 formed first via major mergers, and the metal-poor outer halo grew via numerous minor mergers.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/ac9670