[Speaker1]

Takafumi Tsukui,
SOKENDAI 3rd year (D1),
(Supervisor: Satoru Iguchi, Hiroshi Nagai, Yuichi Matsuda)

[Title1]

Galactic Dynamics and Dark Matter Profile of NGC1380 with ALMA and VLT/MUSE.

[Abstract1]

ALMA’s high resolution and high sensitivity images enable us to obtain kinematics of molecular gas in the center of early-type galaxies (~1kpc) complementarily to the stellar dynamics obtained with optical IFU instrument. The cold molecular gas dynamics is a powerful tracer of mass distribution of galaxies because the velocity dispersion is low(~10km/s) and the simple rotational model is applicable. To understand the interaction between dark matter and baryonic matter in the galaxy evolution history, it is fundamental to measure dark matter distribution in galaxies. However, it is difficult to derive the dark matter profile in the central region of early-type galaxies because of the lack of neutral hydrogen gas in early-type galaxies and the degeneracy between dynamical stellar M/L and dark matter distribution. To resolve this difficulty, we conducted a combined analysis of ALMA cold molecular gas kinematics data and MUSE stellar kinematics data of early-type fast rotator galaxy NGC1380. Our strategy is to measure BH mass and stellar mass well in the central region (~radius of 6”, 500pc) with the cold gas kinematics. Then we derive dark matter profile with the stellar kinematics which is available in a wide field of view(~radius of 120’’, 10kpc) with the help of information of the central cold gas modeling. Dynamical measurement of stellar M/L and BH mass is conducted with ALMA high angular resolution data (0.24”×0.18” ~ 21pc×16pc where BH sphere of influence of the resulted BH mass is 0.37”~ 33pc). Simple gas rotational disk model reproduce observed data cube well. The obtained BH mass of 3.38×10^8^{+0.30}_{-0.24} solar masses is close to the estimated value of 3.9×10^8 solar masses from the empirical M – sigma relation. With Jeans Anisotropic Models (JAM; Cappellari 2008) of stellar kinematics, we found that the substantial dark matter halo needs to exist to maintain flat velocity profile at large radius. However, the mass model obtained with ALMA cold gas modeling cannot reproduce the central high-velocity dispersion peak in the stellar kinematics data (~10” 900pc ), which may indicate several possibilities including the steep M/L variation and hidden non-axisymmetric bar structure. We obtained dark matter profile by using information from the central gas rotational disk model as a prior knowledge with Bayesian inference. The obtained central slope of the dark matter was gamma=0.45^{+0.11}_{-0.10} which is lower than 1.0 NFW profile predict. 

[Speaker2]

Shishido, Takaharu,
SOKENDAI 3rd year (D1),
(Supervisor:Takayuki tomaru, Yoichi Aso, Ryutaro Takahashi)

[Title2]

A study of the sapphire suspension fiber for cryogenic gravitational wave detector KAGRA