Browsing by Author "Momjian, Emmanuel"

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An Outflow-driven Water Maser Associated with Positive Black Hole Feedback in the Dwarf Galaxy Henize 2–10
(American Astronomical Society, 2024-07) Gim, Hansung B.; Reines, Amy E.; Momjian, Emmanuel; Darling, Jeremy
Henize 2–10 is a dwarf galaxy experiencing positive black hole (BH) feedback from a radio-detected low-luminosity active galactic nucleus. Previous Green Bank Telescope (GBT) observations detected a H2O "kilomaser" in Henize 2–10, but the low angular resolution (33'') left the location and origin of the maser ambiguous. We present new Karl G. Jansky Very Large Array observations of the H2O maser line at 22.23508 GHz in Henize 2–10 with ∼2'' resolution. These observations reveal two maser sources distinct in position and velocity. The first maser source is spatially coincident with the known BH outflow and the region of triggered star formation ∼70 pc to the east. Combined with the broad width of the maser (W50 ∼ 66 km s−1), this confirms our hypothesis that part of the maser detected with the GBT is produced by the impact of the BH outflow shocking the dense molecular gas along the flow and at the interface of the eastern star-forming region. The second maser source lies to the southeast, far from the central BH, and has a narrow width (W50 ∼ 8 km s−1), suggesting a star formation–related origin. This work has revealed the nature of the H2O kilomaser in Henize 2–10 and illustrates the first known connection between outflow-driven H2O masers and positive BH feedback.
DIISC-I: The Discovery of Kinematically Anomalous H i Clouds in M 100
(American Astronomical Society, 2021-11) Gim, Hansung B.; Borthakur, Sanchayeeta; Momjian, Emmanuel; Padave, Mansi; Jansen, Rolf A.; Nelson, Dylan; Heckman, Timothy M.; Kennicutt Jr., Robert C.; Fox, Andrew J.; Pineda, Jorge L.; Thilker, David; Kauffmann, Guinevere; Tumlinson, Jason
We report the discovery of two kinematically anomalous atomic hydrogen (H i) clouds in M 100 (NGC 4321), which was observed as part of the Deciphering the Interplay between the Interstellar medium, Stars, and the Circumgalactic medium (DIISC) survey in H i 21 cm at 3.3 km s−1 spectroscopic and 44″ × 30″ spatial resolution using the Karl G. Jansky Very Large Array. 15 15 The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. These clouds were identified as structures that show significant kinematic offsets from the rotating disk of M 100. The velocity offsets of 40 km s−1 observed in these clouds are comparable to the offsets seen in intermediate-velocity clouds (IVCs) in the circumgalactic medium (CGM) of the Milky Way and nearby galaxies. We find that one anomalous cloud in M 100 is associated with star-forming regions detected in Hα and far-ultraviolet imaging. Our investigation shows that anomalous clouds in M 100 may originate from multiple mechanisms, such as star formation feedback-driven outflows, ram pressure stripping, and tidal interactions with satellite galaxies. Moreover, we do not detect any cool CGM at 38.8 kpc from the center of M 100, giving an upper limit of N(H i) ≤1.7 × 1013 cm−2 (3σ). Since M 100 is in the Virgo cluster, the nonexistence of neutral/cool CGM is a likely pathway for turning it into a red galaxy.