Investigation of the obscuring circumnuclear torus in the active galaxy Mrk231

Abstract

Active galaxies are characterized by prominent emission from their nuclei. In the ‘unified’ view of active galaxies, the accretion of material onto a massive compact object—now generally believed to be a black hole—provides the fundamental power source1. Obscuring material along the line of sight can account for the observed differences in the nuclear emission2,3, which determine the classification of AGN (for example, as Seyfert 1 or Seyfert 2 galaxies). Although the physical processes of accretion have been confirmed observationally4,5, the structure and extent of the obscuring material have not been determined. Here we report observations of powerful hydroxyl (OH) line emissions that trace this obscuring material within the circumnuclear environment of the galaxy Markarian 231. The hydroxyl (mega)-maser emission shows the characteristics of a rotating, dusty, molecular torus (or thick disk) located between 30 and 100 pc from the central engine. We now have a clear view of the physical conditions, the kinematics and the spatial structure of this material on intermediate size scales, confirming the main tenets of unification models.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: Hydroxyl and radio-continuum emission in the nucleus of Mrk231.
Figure 2: Hydroxyl emission spectra of Mrk231 traced at different scale sizes.
Figure 3: Circumnuclear kinematics in Mrk231.

References

  1. 1

    Rees, M. J. Black hole models for active galactic nuclei. Annu. Rev. Astron. Astrophys. 22, 471–506 (1984)

    ADS  CAS  Article  Google Scholar 

  2. 2

    Krolik, J. H. & Begelman, M. C. Molecular tori in Seyfert galaxies: Feeding the monster and hiding it. Astrophys. J. 329, 702–711 (1988)

    ADS  CAS  Article  Google Scholar 

  3. 3

    Krolik, J. H. Active Galactic Nuclei (Princeton Series in Astrophysics, Princeton Univ. Press, Princeton, New Jersey, 1999)

    Google Scholar 

  4. 4

    Greenhill, L. J. et al. Detection of a subparsec diameter disk in the nucleus of NGC 4258. Astrophys. J. 440, 619–627 (1995)

    ADS  Article  Google Scholar 

  5. 5

    Gallimore, J. F., Baum, S. F. & O'Dea, C. P. A direct image of the obscuring disk surrounding an active galactic nucleus. Nature 388, 852–854 (1997)

    ADS  CAS  Article  Google Scholar 

  6. 6

    Baan, W. A. Powerful extragalactic masers. Nature 315, 26–31 (1985)

    ADS  CAS  Article  Google Scholar 

  7. 7

    Maloney, P. R. Powerful water masers in active galactic nuclei. Publ. Astron. Soc. Pacif. 19, 401–421 (2002)

    ADS  CAS  Article  Google Scholar 

  8. 8

    Herrnstein, J. R. et al. Polarimetric observations of the masers in NGC 4258: an upper limit on the large-scale magnetic field 0.2 parsecs from the central engine. Astrophys. J. 508, 243–247 (1998)

    ADS  Article  Google Scholar 

  9. 9

    Diamond, P. J., Lonsdale, Co. J., Lonsdale, Ca. J. & Smith, H. E. Global VLBI observations of the compact OH megamaser emission from III ZW 35 and IRAS 17208-0014. Astrophys. J. 511, 178–184 (1999)

    ADS  CAS  Article  Google Scholar 

  10. 10

    Lonsdale, Co. J., Lonsdale, Ca. J., Diamond, P. J. & Smith, H. E. Symmetric parsec-scale OH megamaser structures in Arp 220. Astrophys. J. 507, 615–654 (1998)

    Article  Google Scholar 

  11. 11

    Pihlström, Y. M., Conway, J. E., Booth, R. S., Diamond, P. J. & Polatidis, A. G. EVN and MERLIN observation of III Zw 35. Astron. Astrophys. 377, 377–413 (2001)

    Article  Google Scholar 

  12. 12

    Baan, W. A. Infrared properties of OH galaxies. Astrophys. J. 338, 804–811 (1989)

    ADS  CAS  Article  Google Scholar 

  13. 13

    Baan, W. A., Salzer, J. J. & LeWinter, D. Optical classification of megamaser galaxies. Astrophys. J. 509, 633–645 (1998)

    ADS  CAS  Article  Google Scholar 

  14. 14

    Ulvestad, J. S. et al. Subrelativistic radio jets and parsec-scale absorption in two Seyfert galaxies. Astrophys. J. 517, L81–L84 (1999)

    ADS  CAS  Article  Google Scholar 

  15. 15

    Ulvestad, J. S., Wrobel, J. M. & Carilli, C. L. Radio continuum evidence for outflow and absorption in the Seyfert 1 galaxy Markarian 231. Astrophys. J. 516, 127–140 (1998)

    ADS  Article  Google Scholar 

  16. 16

    Richards, A. et al. in Galaxies and their Constituents at Highest Angular Resolutions (eds Schilizzi, R. T., Vogel, S. F. P. & Elvis, M. S.) 212–215 (IAU Symposium 205, Astronomical Society of the Pacific, San Francisco, 2001)

    Google Scholar 

  17. 17

    Taylor, G. B., Silver, C. S., Ulvestad, J. S. & Carilli, C. L. The starburst in the central kiloparsec of Markarian 231. Astrophys. J. 519, 185–190 (1999)

    ADS  CAS  Article  Google Scholar 

  18. 18

    Bryant, P. M. & Scoville, N. Z. High-resolution CO observations of the ultraluminous infrared galaxy Markarian 231. Astrophys. J. 457, 678–692 (1996)

    ADS  CAS  Article  Google Scholar 

  19. 19

    Downes, D. & Solomon, P. M. Rotating nuclear rings and extreme starbursts in ultraluminous galaxies. Astrophys. J. 507, 615–654 (1998)

    ADS  CAS  Article  Google Scholar 

  20. 20

    Carilli, C. L., Wrobel, J. M. & Ulvestad, J. S. A subkiloparsec disk in Markarian 231. Astron. J. 115, 928–937 (1998)

    ADS  CAS  Article  Google Scholar 

  21. 21

    Baan, W. A., Henkel, C. & Güsten, R. Rotationally excited OH in megamaser galaxies. Astron. Astrophys. 185, 14–24 (1987)

    ADS  Google Scholar 

  22. 22

    Randell, J., Field, D., Jones, K. N., Yates, J. A. & Gray, M. D. The OH zone in OH megamaser galaxies. Astron. Astrophys. 300, 659–674 (1995)

    ADS  CAS  Google Scholar 

  23. 23

    Baan, W. A., Wood, P. A. D. & Haschick, A. D. Broad hydroxyl emission in IC 4553. Astrophys. J. 260, L49–L52 (1982)

    ADS  CAS  Article  Google Scholar 

  24. 24

    Keiichi, W. & Norman, C. A. Obscuring material around Seyfert nuclei with starbursts. Astrophys. J. 566, L21–L24 (2002)

    Article  Google Scholar 

  25. 25

    v. Langevelde, H. et al. A thin circumnuclear disk in NGC 4261. Astron. Astrophys. 354, L45–L48 (2000)

    ADS  Google Scholar 

  26. 26

    Schmitt, H. R. et al. Testing the unified model with a infrared-selected sample of Seyfert galaxies. Astrophys. J. 555, 663–672 (2001)

    ADS  Article  Google Scholar 

  27. 27

    William, J., Biretta, J. A. & Livio, M. Formation of the radio jet in M87 at 100 Schwarzschild radii from the central black hole. Nature 401, 891–892 (1999)

    ADS  Article  Google Scholar 

Download references

Acknowledgements

We thank C. Carilli for providing a map of the diffuse continuum structure in Mrk231. H.-R.K. thanks O. Möller for advice on programming in OpenGL software. The European VLBI Network is a joint facility of European, Chinese, South African and other radio astronomy institutes funded by their national research councils. The Westerbork Synthesis Radio Telescope is operated by ASTRON (Netherlands Foundation for Research in Astronomy) with support from the Netherlands Foundation for Scientific Research (NWO).

Author information

Affiliations

Authors

Corresponding author

Correspondence to Hans-Rainer Klöckner.

Ethics declarations

Competing interests

The authors declare that they have no competing financial interests.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Klöckner, H., Baan, W. & Garrett, M. Investigation of the obscuring circumnuclear torus in the active galaxy Mrk231. Nature 421, 821–823 (2003). https://doi.org/10.1038/nature01381

Download citation

Further reading

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.