1. Water masers in AGN Paola Castangia INAF-Osservatorio Astronomico di Cagliari
High-z water maser:
V. Impellizzeri (NRAO, Charlottesville)
J. McKean (ASTRON, Dwingeloo)
C. Henkel, A. Roy, A. Brunthaler (MPIfR, Bonn)
O.Wucknitz (AIfA, Bonn)
Swift Survey:
F. Panessa (INAF-IASF Roma)
A. Tarchi (INAF-OA Cagliari)
C. Henkel (MPIfR, Bonn)
M. Kadler (Bamberg University)
A. Tilak (CfA, Boston)

2. Overview Introduction:
extragalactic masers
Disk-masers
jet-masers
Monitoring the high-redshift water maser in MGJ
Swift survey of H2O masers in AGN
Conclusions and future plans

3. Water masers Most observed line:
Rest frequency GHz (λ =1.3 cm)
rotational transition
Trace a warm and dense gas
T > 300 K
N(H2) > 107 cm-3
In the Milky Way is associated with young stellar objects (YSO) or evolved stars
Typical luminosity 10-4 LSUN (can reach 1 LSUN in W49N)

4. Extragalactic H2O masers
Known extragalactic masers are more than 100
Some of them are associated with star formation and can reach 8 LSUN (NGC 2146; Tarchi et al. 2002)
The majority are luminous (LH2O can reach 30,000 LSUN!!) and are found in the central region of AGN, at a few parsecs from the nuclear engine in:
Accretion disks (e.g. NGC 4258, UGC3789)
Jets (e.g. Mrk348, NGC1052)

5. Extragalactic H2O masers
So far they have been found mostly in radio quiet AGN (Seyfert 2 or LINER) in the local Universe (z < 0.06) with few exceptions:
The FRII 3C403 at z=0.06
(Tarchi et al. 2003)
The type 2 quasar SDSS J at z=0.66
(Barvainis & Antonucci 2005)
The type 1 quasar MG J at z=2.64!
(Impellizzeri, McKean, Castangia et al. 2008, Nature, 456, 927)

6. Extragalactic H2O masers as astronomical tools
H2O masers can be mapped at high resolution with the Very Long Baseline Interferometry (VLBI) technique
They allow us to study the structure and the dynamics of the gas in the inner parsecs of AGN:
Disk-maser studies
Jet-maser
Disk geometry and black hole masses (e. g. NGC 4258, Herrnstein et al. 1999)
Evolution of the jet (e. g. Mrk348 Peck et al. 2003)

7. Disk-masers 3 groups of water maser lines systemic lines
NGC 4258
3 groups of water maser lines
systemic lines
high-velocity lines
Systemic velocity
Redshifted
Blueshifted
Greenhill et al. 1995

8. Disk-masers High-velocity lines (tangential points) VHV = VR
Systemic lines (l.o.s to the core)
dVS/ dt =VR2/ RS
NGC 4258
If RS=RHV single-dish observations can give an estimate of the disk radius!

9. Disk-masers PV diagram  θS Velocity drift  RS D = RS / θS
(Reid et al. 2009)
D = RS / θS
DU3789 = 49.9±7.0 Mpc
MBH = 1.09 × 107MSUN
(Braatz et al. 2010)
DN4258 = 7.2±0.5 Mpc
MBH = (3.9±0.3) × 107MSUN
(Herrnstein 1999)

10. Jet-masers Jet-cloud interaction Mrk 348
(Peck et al. 2003)
Continuum and line flux densities are correlated
Reverberation maps give:
Vshock, ρj, ρ0

11. Outflow-masers: Circinus
H2O masers trace a warped edge-on accretion disk and a wide-angle outflow
Outflow l.o.s velocity:
± 160 km/s
The warps collimate the outflow
(Greenhill et al. 2003)

12. MGJ
z=0.66 z=2.64!!
MG J
is a radio-loud type 1 quasar, rich of molecular gas and dust
has a magnification factor of ~35 A1 A2 B C
The lens is an elliptical galaxy at z=0.96
HST image, R, I, and H bads

13. An H2O maser at redshift 2.64 Observing frequency: 6.1 GHz
Effelsberg
Observing frequency:
6.1 GHz
Isotropic luminosity:
10,000 L(sun) HI CO
EVLA
Coincident with A1+A2
Impellizzeri, McKean, Castangia et al. 2008, Nature, 456, 927

14. Why it is important?
Indicates evolution in the luminosity function and a larger volume density of luminous masers at redshift 2.64 than in the local Universe
AGN studies at cosmological distances
T > 300 K, n (H2) > 107 cm-3
Maps of accretion disks at cosmological z
res 15 pc  0.5 pc
Maser physics:
Allow to estimate the beaming angle
In MG J
Angular distance A1-A2  0.5 arcsec
Beaming angle > 0.5 arcsec

15. Follow ups
VLBI spectroscopic observations to establish the position of maser spots w.r.t. the radio continuum
VLBI continuum observations at L and X band to improve the lens model
Single-dish monitoring (line and continuum), to investigate the nature of the maser emission (disk- or jet-maser?)

16. Arecibo monitoring Observations: Goals of the monitoring:
3.5 hrs (total observing time) at ~6 weeks intervals
100 MHz bandwidth
2048 ch.  res. 2.4 km/s
The Arecibo 300-m telescope
Goals of the monitoring:
Detect possible flares and/or correlations between continuum-line flux density (jet-maser case)
Reveal the presence of satellite lines and velocity drift of systemic features (disk-maser case)

17. Arecibo monitoring Gaussian fit 30,000 LSUN The most luminous maser!
Main line:
V=-278±5 km/s
FWHM=174±5 km/s
26,000 LSUN
Satellite line:
V=+470±10 km/s
FWHM=100±10 km/s
5,000 LSUN
October 14-15, 2008
res. ~20 km/s
1 hr on source
rms 0.2 mJy
Satellite line?
30,000 LSUN
The most luminous maser!
Castangia et al. submit.

18. Arecibo monitoring February 2009, most sensitive observation:
the satellite line is not detected
main line profile shows 3 comp.
Castangia et al. submit.
The velocity of the most redshifted comp. Increased by 10 km/s in ~276 days
 velocity drift?

19. Arecibo monitoring
Continuum and line flux density are surprisingly stable
No velocity drift > 2 km/s per year
Castangia et al. submit.

20. Arecibo monitoring Jet-maser: Disk maser:
The large linewidth and the absence of a triple-peak profile is consistent, the stability is not!
But…statistics of jet-masers is poor!
known jet-masers: Mrk348, NGC1068, NGC1052, M51
Disk maser:
The tentative detection of the redshifted feature is compatible with the disk-maser hypohtesis
The main line is the truly blueshifted component
 no perceptible velocity drift is expected

21. H2O and X-rays
H2O maser sources associated with AGN tend to show a high column density (NH > 1023 cm-2) or are even Compton-thick (NH > 1024 cm-2)
(Zhang et al. 2006, Greenhill et al. 2008)
76% of disk-maser are Compton-thick (Greenhill et al. 2008)
LX may shape the accretion disk structure (Tilak et al. 2008)
Statistics is poor!
Lack of X-ray data for most of the known maser sources!
(Greenhill et al. 2008)

22. Swift survey Swift intruments:
UVOT 170 – 650 nm
XRT keV
BAT keV
The sample: 95 galaxies where H2O emission is believed to be associated with AGN activity
45 have no published X-ray data
Fill-in project
10 ks per galaxy

23. Swift survey First results
XRT results: 21 new detections
40% increase of the maser sources with X-ray data
2 disk-masers (UGC 3789 and NGC 6264)
Follow up  XMM observations for 5 sources
BAT results: 28/95 detections
Detection rate 30%
 one of the highest ever obtained!

24. Summary and future plans
MG J
Arecibo monitoring helped shed light on the origin of the maser
The jet-maser scenario is the most likely but the disk maser hypothesis cannot be excluded
Include the results from the other follow ups (VLBI, etc…)
Swift survey
Increased the number of maser sources with X-ray data
High BAT detection rate confirms the maser sample is interesting
Reduce and analyse XMM data
Follow-up the other new detections with Swift or other X-ray telescopes
Analyze the statistical result of the entire sample (NH distribution, LX versus RH2O, ect.)