Extended Structure and Fate of the Nucleus in Henize 2-10

Dieu D. Nguyen; Anil C. Seth; Amy E. Reines; Mark den Brok; David Sand; Brian McLeod

doi:10.1088/0004-637X/794/1/34

paper

Extended Structure and Fate of the Nucleus in Henize 2-10

arXiv:1408.4446 · doi:10.1088/0004-637X/794/1/34

Abstract

We investigate the structure and nuclear region of the black hole (BH) hosting galaxy Henize2-10. Surface brightness (SB) profiles are analyzed using Magellan/Megacam $g$ - and $r$ -band images. Excluding the central starburst, we find a best-fit two component Sérsic profile with $n_{in} \sim 0.6$ , $r_{eff,in} \sim$ 260~pc, and $n_{out} \sim 1.8$ , $r_{eff, out} \sim$ 1 kpc. Integrating out to our outer most data point (100 arc sec $\sim$ 4.3 kpc), we calculate $M_{g} = - 19.2$ and $M_{r} = - 19.8$ . The corresponding enclosed stellar mass is $M_{⋆} \sim (10 \pm 3) \times 1 0^{9}$ M $_{⊙}$ , $\sim 3 \times$ larger than previous estimates. Apart from the central $≲$ 500 pc, with blue colors and an irregular morphology, the galaxy appears to be an early-type system. The outer color is quite red, $(g - r)_{0} = 0.75$ , suggesting a dominant old population. We study the nuclear region of the galaxy using archival Gemini/NIFS $K$ -band adaptive optics spectroscopy and {\it Hubble Space Telescope} imaging. We place an upper limit on the BH mass of $\sim 1 0^{7} M_{⊙}$ from the NIFS data, consistent with that from the $M_{BH}$ -radio-X-ray fundamental plane. No coronal lines are seen, but a Br $γ$ source is located at the position of the BH with a luminosity consistent with the X-ray emission. The starburst at the center of Henize 2-10 has led to the formation of several super star clusters, which are within $\sim$ 100 pc of the BH. We examine the fate of the nucleus by estimating the dynamical masses and dynamical friction timescales of the clusters. The most massive clusters ( $\sim 1 0^{6} M_{⊙}$ ) have $τ_{dyn} ≲ 200$ Myr, and thus Henize 2-10 may represent a rare snapshot of nuclear star cluster formation around a pre-existing massive BH.

arXiv comment15 pages, 9 figures, ApJ accepted

Extended Structure and Fate of the Nucleus in Henize 2-10

Abstract

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