Submillimeter water megamasers in nearby AGNs Dom Pesce Presentation for SES APS conference November 12, 2016

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers What are they? 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers What are they? The water molecule has a rotational transition with a rest frequency of 22 GHz (radio regime) 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers What are they? The water molecule has a rotational transition with a rest frequency of 22 GHz (radio regime) Under certain physical conditions, the water molecules can experience a population inversion, leading to maser activity 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers What are they? The water molecule has a rotational transition with a rest frequency of 22 GHz (radio regime) Under certain physical conditions, the water molecules can experience a population inversion, leading to maser activity 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers Where are they? 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers Where are they? Observed in thin, edge-on accretion disks around supermassive black holes (SMBHs) in active galactic nuclei (AGNs) NGC 5765b 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers Why do we care? NGC 5765b 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers Why do we care? They provide the only means of directly mapping molecular gas in AGNs on sub-parsec scales NGC 5765b 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers Why do we care? They provide the only means of directly mapping molecular gas in AGNs on sub-parsec scales They act as test masses inside the SMBH’s sphere of influence, allowing us to kinematically measure the mass of the black hole 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers 22 GHz water megamasers Why do we care? They provide the only means of directly mapping molecular gas in AGNs on sub-parsec scales They act as test masses inside the SMBH’s sphere of influence, allowing us to kinematically measure the mass of the black hole Their geometry is such that we can use them to make distance measurements to the host galaxy 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

What 22 GHz masers can’t tell us 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

What 22 GHz masers can’t tell us The 22 GHz masers are excellent dynamical probes of the accretion disk But they can’t tell us much about the physical conditions Gas temperature Gas density Dust temperature 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

Submillimeter water megamasers can help do what 22 GHz alone cannot 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

Submillimeter water megamasers can help do what 22 GHz alone cannot The water molecule has a complex structure of rotational energy levels para ortho 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

Submillimeter water megamasers can help do what 22 GHz alone cannot The water molecule has a complex structure of rotational energy levels para ortho 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

Submillimeter water megamasers can help do what 22 GHz alone cannot The water molecule has a complex structure of rotational energy levels Several of these transitions can generate maser emission in the sub-mm wavelength range accessible with ALMA 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

Submillimeter water megamasers can help do what 22 GHz alone cannot The water molecule has a complex structure of rotational energy levels Several of these transitions can generate maser emission in the sub-mm wavelength range accessible with ALMA Combining observations of multiple transitions will allows us to constrain the physical conditions in the accretion disk as a function of radius 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

Submillimeter water megamasers can help do what 22 GHz alone cannot Circinus 22 GHz 321 GHz 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

Submillimeter water megamasers can help do what 22 GHz alone cannot NGC 4945 22 GHz 321 GHz 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

22 GHz megamasers • What they can’t tell us • Submillimeter megamasers Conclusions 22 GHz water megamasers have proven to be useful tools for measuring SMBH masses, distances to galaxies, and H0 ALMA has now opened up the possibility of studying sub-mm megamasers Observations of multiple masing transitions in a single system will constrain the physical conditions in the accretion disk Several systems have already been observed to host sub-mm megamasers The ultimate goal is to be able to map out the radial temperature and density profiles of these accretion disks Upcoming work will focus on spatially resolving the sub-mm maser distribution ALMA can do this for the closest systems More distant targets will require (sub)mm-VLBI 22 GHz megamasers • What they can’t tell us • Submillimeter megamasers

References Braatz, J. A., et al. 2010, ApJ, 718, 657 Gao, F. et al. 2016, ApJ, 817, 128 Gray, M. D. et al. 2016, MNRAS, 456, 374 Hagiwara, Y. et al. 2013, ApJL, 768, L38 Humphreys, E. M. L. et al. 2016, A&A, 592, L13 Lo, K. Y. 2005, ARAA, 43, 625 Pesce, D. W., Braatz, J. A., & Impellizzeri, C. M. V. 2016, ApJ, 827, 68 Reid, M. J. et al. 2013, ApJ, 767, 154 • References •