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RISS 인기검색어
- 검색키워드
- 저자 : Braatz J. A. (검색결과 3 건)
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THE MEGAMASER COSMOLOGY PROJECT. IX. BLACK HOLE MASSES FOR THREE MASER GALAXIES
Gao, F.,Braatz, J. A.,Reid, M. J.,Condon, J. J.,Greene, J. E.,Henkel, C.,Impellizzeri, C. M. V.,Lo, K. Y.,Kuo, C. Y.,Pesce, D. W.,Wagner, J.,Zhao, W. American Astronomical Society 2017 The Astrophysical journal Vol.834 No.1
<P>As part of the Megamaser Cosmology Project, we present VLBI maps of nuclear water masers toward five galaxies. The masers originate in sub-parsec circumnuclear disks. For three of the galaxies, we fit Keplerian rotation curves to estimate their supermassive black hole (SMBH) masses, and determine (2.9 +/- 0.3) x 10(6)M(Theta) for J0437+2456, (1.7 +/- 0.1) x 10(7)M(Theta) for ESO 558-G009, and (1.1 +/- 0.2) x 10(7)M(Theta) for NGC 5495. In the other two galaxies, Mrk 1029 and NGC 1320, the geometry and dynamics are more complicated and preclude robust black hole mass estimates. Including our new results, we compiled a list of 15 VLBI-confirmed disk maser galaxies with robust SMBH mass measurements. With this sample, we confirm the empirical relation of R-out proportional to 0.3M(SMBH) reported in Wardle & Yusef-Zadeh. We also find a tentative correlation between maser disk outer radii and Wide-Field Infrared Survey Explorer luminosity. We find no correlations of maser disk size with X-ray 2-10 keV luminosity or [O III] luminosity.</P>
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MEGAMASER DISKS REVEAL A BROAD DISTRIBUTION OF BLACK HOLE MASS IN SPIRAL GALAXIES
Greene, J. E.,Seth, A.,Kim, M.,Lä,sker, R.,Goulding, A.,Gao, F.,Braatz, J. A.,Henkel, C.,Condon, J.,Lo, K. Y.,Zhao, W. American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.826 No.2
<P>We use new precision measurements of black hole (BH) masses from water megamaser disks to investigate scaling relations between macroscopic galaxy properties and supermassive BH mass. The megamaser-derived BH masses span 10(6)-10(8) M-circle dot, while all the galaxy properties that we examine (including total stellar mass, central mass density, and central velocity dispersion) lie within a narrower range. Thus, no galaxy property correlates tightly with M-BH in similar to L* spiral galaxies as traced by megamaser disks. Of them all, stellar velocity dispersion provides the tightest relation, but at fixed sigma* the mean megamaser M-BH are offset by -0.6 +/- 0.1 dex relative to early-type galaxies. Spiral galaxies with non-maser dynamical BH masses do not appear to show this offset. At low mass, we do not yet know the full distribution of BH mass at fixed galaxy property; the non-maser dynamical measurements may miss the low-mass end of the BH distribution due to an inability to resolve their spheres of influence and/or megamasers may preferentially occur in lower-mass BHs.</P>
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Enhancing the H<sub>2</sub>O Megamaser Detection Rate Using Optical and Mid-infrared Photometry
Kuo, C. Y.,Constantin, A.,Braatz, J. A.,Chung, H. H.,Witherspoon, C. A.,Pesce, D.,Impellizzeri, C. M. V.,Gao, F.,Hao, Lei,Woo, J.-H.,Zaw, Ingyin American Astronomical Society 2018 The Astrophysical journal Vol.860 No.2
<P>Water megamasers from circumnuclear disks in galaxy centers provide the most accurate measurements of supermassive black hole masses and uniquely probe the subparsec accretion processes. At the same time, these systems offer independent crucial constraints of the Hubble constant in the nearby universe, and thus, the arguably best single constraint on the nature of dark energy. The chances of finding these golden standards are, however, abysmally low, at less than or similar to 3% overall for any level of water maser emission detected at 22 GHz and less than or similar to 1% for those exhibiting disk-like configuration. We provide here a thorough summary of the current state of detection of water megamaser disks along with a novel investigation of the likelihood of increasing their detection rates based on a multivariate parameter analysis of the optical and mid-infrared (mid-IR) photometric properties of the largest database of galaxies surveyed for 22 GHz emission. We find that galaxies with water megamaser emission tend to be associated with strong emission in all Wide-field Infrared Survey Explorer mid-IR wavelengths, with the strongest enhancement in the W4 band, at 22 mu m, as well as with previously proposed and newly found indicators of active galactic nucleus strength in the mid-IR, such as red W1 - W2 and W1 - W4 colors, and the integrated mid-IR luminosity of the host galaxy. These trends offer a potential boost of the megamaser detection rates to 6%-15%, or a factor of 2-8 relative to the current rates, depending on the chosen sample selection criteria, while fostering real chances for discovering. 20 new megamaser disks.</P>
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