Hostname: page-component-cd9895bd7-lnqnp Total loading time: 0 Render date: 2024-12-24T13:18:32.160Z Has data issue: false hasContentIssue false

The impact of metallicity and X-rays on star formation

Published online by Cambridge University Press:  27 April 2011

Marco Spaans
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen, the Netherlands email: [email protected]
Aycin Aykutalp
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen, the Netherlands email: [email protected]
Seyit Hocuk
Affiliation:
Kapteyn Astronomical Institute, University of Groningen, P.O. Box 800, 9700 AV Groningen, the Netherlands email: [email protected]
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

Star formation is regulated through a variety of feedback processes. In this study, we treat feedback by metal injection and a UV background as well as by X-ray irradiation. Our aim is to investigate whether star formation is significantly affected when the ISM of a proto-galaxxy enjoys different metallicities and when a star forming cloud resides in the vicinity of a strong X-ray source. We perform cosmological Enzo simulations with a detailed treatment of non-zero metallicity chemistry and thermal balance. We also perform FLASH simulations with embedded Lagrangian sink particles of a collapsing molecular cloud near a massive, 107 M, black hole that produces X-ray radiation.

We find that a multi-phase ISM forms for metallicites as small as 10−4 Solar at z = 6, with higher (10−2Z) metallicities supporting a cold (<100 K) and dense (>103 cm−3) phase at higher (z = 20) redshift. A star formation recipe based on the presence of a cold dense phase leads to a self-regulating mode in the presence of supernova and radiation feedback. We also find that when there is strong X-ray feedback a collapsing cloud fragments into larger clumps whereby fewer but more massive protostellar cores are formed. This is a consequence of the higher Jeans mass in the warm (50 K, due to ionization heating) molecular gas. Accretion processes dominate the mass function and a near-flat, non-Salpeter IMF results.

Type
Contributed Papers
Copyright
Copyright © International Astronomical Union 2011

References

Cazaux, S. & Spaans, M. 2004, ApJ, 611, 40CrossRefGoogle Scholar
Cazaux, S. & Spaans, M. 2009, A&A, 496, 365Google Scholar
Federrath, C., Banerjee, R., Clark, P. C., & Klessen, R. S. 2010, ApJ, 713, 269CrossRefGoogle Scholar
Greif, T. M., Glover, S. C. O., Bromm, V., & Klessen, R. S. 2010, ApJ, 716, 510CrossRefGoogle Scholar
Hocuk, S. & Spaans, M. 2010, A&A, 510, A110Google Scholar
Jappsen, A.-K., Klessen, R. S., Glover, S. C. O. & Mac Low, M.-M. 2009, ApJ, 696, 1065CrossRefGoogle Scholar
Krumholz, M. R., McKee, C. F., & Klein, R. I. 2004, ApJ, 611, 399CrossRefGoogle Scholar
Meijerink, R. & Spaans, M. 2005, A&A, 436, 397Google Scholar