The megamaser cosmology project. I. very long baseline interferometric observations of UGC 3789

Reid, M. J.; Braatz, J. A.; Condon, J. J.; Greenhill, L. J.; Henkel, C.; Lo, K. Y.

doi:10.1088/0004-637x/695/1/287

Cited by 152 publications

(140 citation statements)

References 28 publications

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“…However, the best VLA resolution at 6 cm is ∼0.4 arcsec, which corresponds to a linear size of ∼20 pc for a source at distance 10 Mpc. This size and the corresponding highest VLA resolution at 20 cm, ∼2 arcsec, is much larger than that of the maser spots observed on sub-pc scales (e.g., Miyoshi et al 1995;Reid et al 2009) and that of potentially associated nuclear continuum sources. (2) Both 6 cm and 20 cm data should have similar beam size.…”

Section: Introductionmentioning

confidence: 81%

Radio properties of H₂O maser host galaxies

Zhang¹,

Henkel²,

Guo³

et al. 2012

A&A

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The 6 cm and 20 cm radio continuum properties of all 85 galaxies with reported 22 GHz H 2 O maser emission and luminosity distance D > 0.5 Mpc are studied. For the total of 55 targets for which both 6 cm and 20 cm measurements exist and for the subsample of 42 sources with masers related to active galactic nuclei (AGN), a spectral index could be determined from an assumed power-law dependence. The mean value of the resulting spectral index is in both cases 0.66 ± 0.07 (S ∝ ν −α ; S : flux density, ν: frequency). Comparing radio properties of the maser galaxies with a sample of Seyferts without detected H 2 O maser, we find that (1) the spectral indices agree within the error limits; and (2) maser host galaxies have higher nuclear radio continuum luminosities, exceeding those of the comparison sample by factors of order 5. Only considering the subsample of galaxies with masers associated with AGN, there seems to be a trend toward rising maser luminosity with nuclear radio luminosity (both at 6 cm and 20 cm). However, when accounting for the Malmquist effect, the correlation weakens to a level, which is barely significant. Overall, the study indicates that nuclear radio luminosity is a suitable indicator to guide future AGN maser searches and to enhance detection rates, which are otherwise quite low (<10%).

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Section: Introductionmentioning

confidence: 81%

Radio properties of H₂O maser host galaxies

Zhang¹,

Henkel²,

Guo³

et al. 2012

A&A

Self Cite

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“…Thousands of galaxies have been searched for maser activity, largely by theMegamaser Cosmology Project (MCP, Reid et al 2009;Braatz et al 2010). By measuring the acceleration of the systemic water maser features, it is possible to measure direct geometric distances to these galaxies (e.g., Humphreys et al 2013).…”

Section: Introductionmentioning

confidence: 99%

Toward Precision Supermassive Black Hole Masses Using Megamaser Disks

Bosch

Greene

Braatz

et al. 2016

ApJ

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Megamaser disks provide the most precise and accurate extragalactic supermassive black hole (BH) masses. Here we describe a search for megamasers in nearby galaxies using the Green Bank Telescope (GBT). We focus on galaxies where we believe that we can resolve the gravitational sphere of influence of the BH and derive a stellar or gas dynamical measurement with optical or NIR observations. Since there are only a handful of super massive BHs that have direct BH mass measurements from more than one method, even a single galaxy with a megamaser disk and a stellar dynamical BH mass would provide necessary checks on the stellar dynamical methods. We targeted 87 objects from the Hobby-Eberly Telescope Massive Galaxy Survey, and detected no new maser disks. Most of the targeted objects are elliptical galaxies with typical stellar velocity dispersions of 250 km s −1 and distances within 130 Mpc. We discuss the implications of our non-detections, whether they imply a threshold X-ray luminosity required for masing, or possibly reflect the difficulty of maintaining a masing disk around much more massive ( 10 8  M  ) BHs at a low Eddington ratio. Given the power of maser disks for probing BH accretion and demographics, we suggest that future maser searches should endeavour to remove remaining sample biases, in order to sort out the importance of these covariant effects.

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“…The parsec-scale environments around supermassive black holes have been probed (e.g., Reid et al 2009;Kuo et al 2011;Greene et al 2013) and Hubble's constant has been constrained (e.g., Herrnstein et al 1999;Braatz et al 2010;Humphreys et al 2013;Kuo et al 2013;Reid et al 2013) through observations of extragalactic water. Hydroxyl (OH) megamasers have been utilized to trace star formation and to estimate the galaxy merger rate (e.g., Darling 2002).…”

Section: Introductionmentioning

confidence: 99%

The Hydroxyl–water Megamaser Connection. I. Water Emission Toward Oh Megamaser Hosts

Wiggins

Migenes

Smidt

2016

ApJ

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Questions surround the connection of luminous extragalactic masers to galactic processes. The observation that water and hydroxyl megamasers rarely coexist in the same galaxy has given rise to a hypothesis that the two species appear in different phases of nuclear activity. The detection of simultaneous hydroxyl and water megamaser emission toward IC694 has called this hypothesis into question, but, because many megamasers have not been surveyed for emission in the other molecule, it remains unclear whether IC694 occupies a narrow phase of galaxy evolution or whether the relationship between megamaser species and galactic processes is more complicated than previously believed. In this paper, we present results of a systematic search for 22 GHz water maser emission among OH megamaser hosts to identify additional objects hosting both megamasers. Our work roughly doubles the number of galaxies searched for emission in both molecules, which host at least one confirmed maser. We confirm with a high degree of confidence ( 8s > ) the detection of water emission toward IIZw96, firmly establishing it as the second object to cohost both water and hydroxyl megamasers after IC694. We find high luminosity, narrow features in the water feature in IIZw96. All dual megamaser candidates appear in merging galaxy systems suggestive that megamasers that coexistance may signal a brief phase along the merger sequence. A statistical analysis of the results of our observations provide possible evidence for an exclusion of H 2 O kilomasers among OH megamaser hosts.

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The megamaser cosmology project. I. very long baseline interferometric observations of UGC 3789

Cited by 152 publications

References 28 publications

Radio properties of H₂O maser host galaxies

Radio properties of H₂O maser host galaxies

Toward Precision Supermassive Black Hole Masses Using Megamaser Disks

The Hydroxyl–water Megamaser Connection. I. Water Emission Toward Oh Megamaser Hosts

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The megamaser cosmology project. I. very long baseline interferometric observations of UGC 3789

Cited by 152 publications

References 28 publications

Radio properties of H2O maser host galaxies

Radio properties of H2O maser host galaxies

Toward Precision Supermassive Black Hole Masses Using Megamaser Disks

The Hydroxyl–water Megamaser Connection. I. Water Emission Toward Oh Megamaser Hosts

Contact Info

Product

Resources

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Radio properties of H₂O maser host galaxies

Radio properties of H₂O maser host galaxies