Low-luminosity Extragalactic H 2 O Masers Yoshiaki Hagiwara

Low-luminosity Extragalactic H 2 O Masers Yoshiaki Hagiwara ASTRON

22 GHz Extragalactic H 2 O Masers High-luminosity (LH 2 O > ~10 Lsun). . . ca. 35 galaxies NGC 3079 (Megamasers) NGC 4258, NGC 3079, NGC 4945, Circinus, . . . Most of these have been found in narrow-line AGNs These masers are associated with AGN-activity. Sherwood et al. ~100 Lsun Low-luminosity (LH 2 O < ~1 Lsun) . . . ca. 10 galaxies NGC 253, M 82, IC 342, M 33, M 51, . . . . Found in nearby star-forming galaxies, starbursts, and AGNs. NOTE: Strongest Galactic H 2 O maser (W 49 N) is as luminous as 1 Lsun. Some Low-L masers arise in star-forming regions.

Why Study the Low-luminosity H 2 O masers? VLBI/VLA actual images Learn something about the extragalactic star-formation. - The evolution and kinematics. - Structures of exotic star-formation in outer galaxies. Learn something about the environment of low-luminosity AGN. - The masers at shock with molecular clouds. Use the masers for Astrometry (IC 10, M 33, LMC, SMC). - Parallaxes establish 3 D-kinematics for the Local group (Brunthaler et al. 2003, 2004). - Proper motions yield galactic kinematics.

Low-luminosity H 2 O Masers

H 2 O maser in the starburst galaxy M 82 Q OH masers (blue-shifted) imply star-formation in the expanding shell of SNR (Pedlar et al. 1999, Wills et al. 1999). Molecular super bubble structures in CO (Matsushita et al. 2000, Weiss et al. 20 Weak (0. 001 -0. 1 Lsun) H 2 O masers (Claussen et al. 1984) VLA at 1" res could not resolve the maser (Baudry & Brouillet 1996). H 2 O Maser Spectrum in M 82 (Baudry, Henkel et al. 1994)

New VLA Observations -Angular res: 0. 1 - 0. 08 arcsec - A Configuration -Velocity range: V(LSR) = 70 -155 km/s -Velocity res: 1. 3 km/s

New 1 New 2 S 1 Xray source S 2 S 1 M 82 New 1 S 1 : Compact HII Region S 2 : 0. 2 arcsec (3. 5 pc) away from Compact HII Region. - Followed up by MERLIN. New 1 & 2 : Weak and narrow lines No nearby continuum New 2 S 2

What is 'S 2 ' and other 'new' masers? No continuum counterparts for these H 2 O masers. The masers are associated with neithermal HII regions nor SNRs. The masers could trace the earlier phase of SF, like bipolar outflows in YSOs. Need for mapping at higher resolution ~ < 0. 01 pc (Signatures of Galactic SF structures ~ < 0. 01 pc) MERLIN, at res ~ 30 mas ~ 0. 2 pc, barely resolved the maser. S 2 CO (2 -1) Intensity map with Pd. BI & the 30 m (Weiss et al. 2001) and positions of H 2 O masers. CO(2 -1) MERLIN 22 GHz S 2 H 2 O

VLA Observations of NGC 4051 -Type 1 Seyfert, D=9. 7 Mpc (VLA-A: 0. 1 arcsec = ~ 5 pc) -Narrow-line Seyfert 1 (NLS 1) (Osterbrock & Pogge 1985) -Weak H 2 O emission (~2 Lsun) (Hagiwara et al. 2004) -H 2 O maser in a type 1 nucleus is rather unique.

Effelsberg and VLA Spectra Quasi-symmetric velocity distribution w. r. t Vlsr = 710 km/s. VLA-A could not resolve the masers at 0. 1 arcsec, or 5 pc. Vsys = 730 km/s No high-velocity emission was seen at rms ~ 5 m. Jy/ch within +- 800 km/s w. r. t Vsys

What is the maser in NGC 4051? The radio continuum peak coincides with the maser. -AGN-activity -But, why is the low-luminosity (~ 2 Lsun) ? Because. . . -Narrow-line Seyfert 1 -Low inclination disc-like configuration Lower column density in the line-of-site Dense and warm molecular gas environment (HCN, HCO+). -Star-forming activity ? ?

The H 2 O maser in M 51 -Nearby star-forming galaxy, hosting a low-luminosity AGN -Weak (0. 1 -1 Lsun) H 2 O maser (Ho et al. 1986) -Hagiwara, Henkel et al. (2001) pinpointed the maser in the vicinity (0. 1", ~5 pc) of the radio continuum nucleus with the VLA-A snap-shot. What is the origin ? AGN-activity or Star-forming-activity? Vsys ~ 470 km/s + : Hard Xray point source Hagiwara, Henkel, et al. (2001) Terashima & Wilson (2004)

New VLA Observations of M 51 0. 08 arcsec resolution A weak blue-shifted (V=445 km/s) and red-shifted (V=538 -585 km/s) components were detected.

Where is the maser in M 51 ? Red-shifted maser: 0. 1" (~ 5 pc ) north the radio (3. 6 -cm) nucleus -Confirmed the results in Hagi, Henkel et al. (2001) A blue-shifted maser: 0. 6" (~30 pc) north-west the nucleus. 3. 6 -cm VLA map: Bradley, Kaiser, Baan (2004)

Origin of the maser in M 51 The red-shifted masers are likely to be related to AGN-activity. The blue-shifted maser might be originated from the gas-rich environment in star-forming region. VLBA resolved the maser ! The presence of a thin disc (Moran et al. 2003)? Blue-shifted emission VLA 3. 6 -cm Red-shifted emission VLA maps: Bradley, Kaiser, Baan (2004)

Jet Maser in NGC 1068 Weak (~10 Lsun) H 2 O maser at the radio knot (C), located ~30 pc north the nucleus. - The maser intensity is variable. - Proper motion over 2 epochs (1983 and 1987)? The origin of the maser (Gallimore et al. 2001) - Molecular outflows in YSOs - Amplifying the radio jet - Shock in molecular clouds in star-forming site C Gallimore et al. (1996) Nakai et al. (1995)

MERLIN Observations of the Jet Maser According to preliminary data analysis. . . The jet maser was not detected in these observations Because of. . . -Intensity variability -Maser is resolved at 30 mas, ~ 3 pc. -MERLIN sensitivity ( rms ~ 4 m. Jy/beam/ch) NGC 1068 Knot C Nucleus S 1 1. 3 -cm Radio Continuum

What do the Low-L H 2 O Masers tell us ? Particular conditions required for H 2 O maser -Density (10^8 - 10^10 cm /cm^3) -Warm (200 - 1000 K) What can be traced by low-luminosity masers? Low-L H 2 O masers are outside of the nucleus (e. g. Claussen & Lo 1986).

In AGN. . . - Disc or torus of low-luminosity AGN (e. g. M 51) - Jet, or non-nuclear region (NGC 1068) - Molecular environments: Outflows in YSOs. In Star-forming and starburst galaxies. . . - Extragalactic star forming phenomena: Shock, disc around a central star, and outflows in YSOs. (M 82 ? ) Scales of Galactic star forming signatures are < 0. 001 -0. 01 pc. - Even VLBI cannot resolve ! - Thermal radio continuum (M 33, IC 10, M 82, …) - Non-thermal SNR - Expanding shell of SNRs. - Startburst nucleus ? (NGC 253)

21 -cm VLA radio continuum - FIR (100 um + 60 um) Low-L H 2 O masers FIR-excess galaxies = OH megamasers Radio-excess galaxies = H 2 Omegamasers 21 cm. VLA data from Condon et al. (1990) (Hagiwara, in prep) 21 -cm compact radio continuum: AGN or SNR FIR (100 um): Dust emission Two different populations of extragalactic H 2 O masers (e. g. Ho et al. 1986)

The future is. . . Water masers in general Diagnosing tools in extragalactic objects -Tracers of High density, warm regions Low-luminosity H 2 O masers -Extragalactic star-forming regions OH(H. Kloeckner and W. Baan), HCHO masers and, of course, we need more H 2 O masers CH 3 OH masers: Massive star-forming regions in outer galaxies ? (not yet detected)