THE NGC 404 NUCLEUS: STAR CLUSTER AND POSSIBLE INTERMEDIATE-MASS BLACK HOLE

By Anil Seth, M. Cappellari, N. Neumayer, N. Caldwell, N. Bastian, Kirsty Olsen, R. Blum, V. Debattista, R. McDermid, Thomas H. Puzia and 1 more. 2010

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We examine the nuclear morphology, kinematics, and stellar populations in nearby S0 galaxy NGC 404 using a combination of adaptive optics assisted near-IR integral-field spectroscopy, optical spectroscopy, and Hubble Space Telescope imaging. These observations enable study of the NGC 404 nucleus at a level of detail possible only in the nearest galaxies. The surface brightness profile suggests the presence of three components: a bulge, a nuclear star cluster (NSC), and a central light excess within the cluster at radii < 3 pc. These components have distinct kinematics with modest rotation seen in the NSC and counter-rotation seen in the central excess. Molecular hydrogen emission traces a disk with rotation nearly orthogonal to that of the stars. The stellar populations of the three components are also distinct, with half of the mass of the NSC having ages of ∼1 Gyr (perhaps resulting from a galaxy merger), while the bulge is dominated by much older stars. Dynamical modeling of the stellar kinematics gives a total NSC mass of 1.1 × 107 M☉. Dynamical detection of a possible intermediate-mass black hole (BH) is hindered by uncertainties in the central stellar mass profile. Assuming a constant mass-to-light ratio, the stellar dynamical modeling suggests a BH mass of <1 × 105 M☉, while the molecular hydrogen gas kinematics are best fitted by a BH with a mass of 4.5+3.5−2.0 × 105 M☉. Unresolved and possibly variable dust emission in the near-infrared and active galactic nucleus-like molecular hydrogen emission-line ratios do suggest the presence of an accreting BH in this nearby LINER galaxy.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/589fb2eb044b449ee0ff2d4d5a2d1b0797553a36

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Citations in the corpus

Masses and scaling relations for nuclear star clusters, and their co-existence with central black holes (2016, unknown): “Perhaps one of the most intriguing observations is the coexistence of NSC and SMBH in galaxies with masses aroundMgal ' 1010M (Filippenko & Ho 2003; Seth et al. 2008a, 2010; Graham & Spitler 2009; Neumayer & Walcher 2012), with the best-studied example being the center of the Milky Way (Schödel et…”
THE MBH–LSPHEROID RELATION AT HIGH AND LOW MASSES, THE QUADRATIC GROWTH OF BLACK HOLES, AND INTERMEDIATE-MASS BLACK HOLE CANDIDATES (2012, methodology): “For the nearby dwarf lenticular galaxy NGC 404, the Galactic extinction corrected H-band magnitude of −19.65 mag from Seth et al. (2010) becomes MKs = −19.85 mag when using an H−Ks color of 0.2 mag (e.g. Balcells et al. 2007).”
Nuclear star clusters (2009, methodology): “In the general case of more distant NSCs, however, one has to rely on integrated light measurements, which makes it nearly impossible to constrain the metal-poor population (Seth et al. 2010; Kacharov et al. 2018).”
Surface brightness profile of the Milky Way’s nuclear star cluster (2014, background): “More recent work, however, shows that many NSCs may indeed by flattened and aligned with the disk of their host galaxies (e.g., Seth et al. 2008a, 2010).”
Observational evidence for intermediate-mass black holes (2017, methodology): “…line region (LINERs) are associated with low-luminosity AGN (e.g., Nagar et al. 2005; Mezcua & Prieto 2014) (Binder et al. 2011), UV variability (Maoz et al. 2005), unresolved and variable hot dust emission (Seth et al. 2010), and mid-infrared (MIR) AGN-like emission lines (Satyapal et al. 2004).”
DWARF GALAXIES WITH OPTICAL SIGNATURES OF ACTIVE MASSIVE BLACK HOLES (2013, background): “NGC 404, a low-mass S0 just beyond the Local Group, also has a likely BH with MBH ∼ 5 × 105 M derived from molecular hydrogen gas kinematics (Seth et al. 2010).”
An expanded Mbh–σ diagram, and a new calibration of active galactic nuclei masses (2010, background): “This does not imply that such ‘intermediate-mass black holes’ (IMBHs) do not exist, indeed, evidence is accumulating that they probably do exist (e.g. Pox 52, Thornton et al. 2008; NGC 4395, Filippenko & Ho 2003; Greene & Ho 2004, 2007; Dong et al. 2007; Naik et al. 2010; Seth et al. 2010).”