They occupy the low-mass end of the BHs at galactic centers, shedding light on the existence and demographics of intermediate-mass BHs (IMBHs), 10 2 M ⊙ ≲ M BH ≲ 10 5 M ⊙.
In addition, low accretion rates and/or a low Eddington limit leading to a low bolometric luminosity make them difficult to distinguish from other sources, such as star formation and ultraluminous X-ray sources (ULXs).Īlthough rare, mBHs in low-mass galaxies constitute an important population for understanding galaxy evolution. This rarity could be due to a low occupation fraction of BHs in small halos, as seen in simulations (e.g., Bellovary et al. 2013) consists of 136 dwarf galaxies that show optical spectroscopic signatures of an active galactic nucleus (AGN) from a parent sample of ∼25,000 emission-line galaxies in the Sloan Digital Sky Survey (SDSS), a detection rate of ∼0.5%. Currently, the largest sample (Reines et al. Evidence of mBHs in dwarf ( M * ≲ 3 × 10 9 M ⊙) and low-mass ( M * ≲ 10 10 M ⊙) galaxies is scarce.
A Milky Way–sized galaxy typically has millions of stellar-mass BHs and ∼1 mBH. Galaxies contain two types of black holes (BHs): stellar-mass BHs have masses of ∼10 M ⊙ and are found scattered throughout the galaxy, and massive BHs (mBHs), most with M BH ≳ 10 5 M ⊙, are usually found in the galactic nucleus. Alternatively, BH growth is intrinsically inefficient in galaxies with low bulge and/or stellar masses, which causes the BHs to be undermassive relative to their hosts, as predicted by some galaxy evolution simulations. These offsets could be due to larger scatter at the low-mass end of these relations. The mass upper limit of the intermediate-mass BH in IC 750 falls roughly two orders of magnitude below the M BH– σ * relation and roughly one order of magnitude below the M BH– M Bulge and M BH– M * relations-larger than the relations' intrinsic scatters of 0.58 ± 0.09 dex, 0.69 dex, and 0.65 ± 0.09 dex, respectively. From near-infrared photometry, we fit a bulge mass of (7.3 ± 2.7) × 10 8 M ⊙ and a stellar mass of 1.4 × 10 10 M ⊙. Fitting the optical spectrum, we measure a nuclear stellar velocity dispersion km s −1. Keplerian rotation curves fitted to these data yield enclosed masses between 4.1 × 10 4 M ⊙ and 1.4 × 10 5 M ⊙, with a mode of 7.2 × 10 4 M ⊙. The position–velocity structure of the maser emission indicates that the central black hole (BH) has a mass less than 1.4 × 10 5 M ⊙.
#Dex online boulder Pc
The masers trace a nearly edge-on, warped disk ∼0.2 pc in diameter, coincident with the compact nuclear X-ray source that lies at the base of the ∼kiloparsec-scale extended X-ray emission. We present a multiwavelength study of the active galactic nucleus in the nearby ( D = 14.1 Mpc) low-mass galaxy IC 750, which has circumnuclear 22 GHz water maser emission.
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