TY - JOUR
T1 - The Cen A galaxy group
T2 - Dynamical mass and missing baryons
AU - Müller, Oliver
AU - Lelli, Federico
AU - Famaey, Benoit
AU - Pawlowski, Marcel S.
AU - Fahrion, Katja
AU - Rejkuba, Marina
AU - Hilker, Michael
AU - Jerjen, Helmut
N1 - Publisher Copyright:
© 2022 O. Müller et al.
PY - 2022/6/1
Y1 - 2022/6/1
N2 - The nearby elliptical galaxy Centaurus A (Cen A) is surrounded by a flattened system of dwarf satellite galaxies with coherent motions. Using a novel Bayesian approach, we measured the mean rotation velocity vrot and velocity dispersion Ï int of the satellite system. We found vrot/Ï inta∼ 0.7, indicating that the satellite system has non-negligible rotational support. Using Jeans equations, we measured a circular velocity of 258 km s-1 and a dynamical mass of 1.2 1013 M· within 800 kpc. In a I cold dark matter cosmological context, we found that the Cen A group has a baryon fraction Mb/M200∼ 0.035 and is missing 14;77% of the cosmologically available baryons. Consequently, Cen A should have a hot intergalactic medium with a mass of ∼8 1011 M·, which is more than ∼20 times larger than current X-ray estimates. Intriguingly, the whole Cen A group lies on the baryonic Tully-Fisher relation defined by individual rotationally supported galaxies, as expected in Milgromian dynamics (MOND) with no need of missing baryons.
AB - The nearby elliptical galaxy Centaurus A (Cen A) is surrounded by a flattened system of dwarf satellite galaxies with coherent motions. Using a novel Bayesian approach, we measured the mean rotation velocity vrot and velocity dispersion Ï int of the satellite system. We found vrot/Ï inta∼ 0.7, indicating that the satellite system has non-negligible rotational support. Using Jeans equations, we measured a circular velocity of 258 km s-1 and a dynamical mass of 1.2 1013 M· within 800 kpc. In a I cold dark matter cosmological context, we found that the Cen A group has a baryon fraction Mb/M200∼ 0.035 and is missing 14;77% of the cosmologically available baryons. Consequently, Cen A should have a hot intergalactic medium with a mass of ∼8 1011 M·, which is more than ∼20 times larger than current X-ray estimates. Intriguingly, the whole Cen A group lies on the baryonic Tully-Fisher relation defined by individual rotationally supported galaxies, as expected in Milgromian dynamics (MOND) with no need of missing baryons.
KW - Cosmology: observations
KW - Dark matter
KW - Galaxies: dwarf
KW - Galaxies: elliptical and lenticular
KW - Galaxies: halos
KW - Galaxies: kinematics and dynamics
KW - cD
UR - http://www.scopus.com/inward/record.url?scp=85132168908&partnerID=8YFLogxK
U2 - 10.1051/0004-6361/202142351
DO - 10.1051/0004-6361/202142351
M3 - Article
SN - 0004-6361
VL - 662
JO - Astronomy and Astrophysics
JF - Astronomy and Astrophysics
M1 - A57
ER -