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تسجيل مستخدم جديدPhysical Characterization of Serendipitously Uncovered Millimeter-wave Line-emitting Galaxies at z~2.5 behind the Local Luminous Infrared Galaxy VV114
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We present a detailed investigation of millimeter-wave line emitters ALMA J010748.3-173028 (ALMA-J0107a) and ALMA J010747.0-173010 (ALMA-J0107b), which were serendipitously uncovered in the background of the nearby galaxy VV114 with spectral scan observations at $lambda$ = 2 - 3 mm. Via Atacama Large Millimeter/submillimeter Array (ALMA) detection of CO(4-3), CO(3-2), and [CI](1-0) lines for both sources, their spectroscopic redshifts are unambiguously determined to be $z= 2.4666pm0.0002$ and $z=2.3100pm0.0002$, respectively. We obtain the apparent molecular gas masses $M_{rm gas}$ of these two line emitters from [CI] line fluxes as $(11.2 pm 3.1) times 10^{10} M_odot$ and $(4.2 pm 1.2) times 10^{10} M_odot$, respectively. The observed CO(4-3) velocity field of ALMA-J0107a exhibits a clear velocity gradient across the CO disk, and we find that ALMA-J0107a is characterized by an inclined rotating disk with a significant turbulence, that is, a deprojected maximum rotation velocity to velocity dispersion ratio $v_{rm max}/sigma_{v}$ of $1.3 pm 0.3$. We find that the dynamical mass of ALMA-J0107a within the CO-emitting disk computed from the derived kinetic parameters, $(1.1 pm 0.2) times 10^{10} M_odot$, is an order of magnitude smaller than the molecular gas mass derived from dust continuum emission, $(3.2pm1.6)times10^{11} M_{odot}$. We suggest this source is magnified by a gravitational lens with a magnification of $mu gtrsim10$, which is consistent with the measured offset from the empirical correlation between CO-line luminosity and width.
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