The sub-stellar birth rate from UKIDSS
| Autor: | Day-Jones, A. C., Marocco, F., Pinfield, D. J., Zhang, Z. H., Burningham, B., Deacon, N., Ruiz, M. T., Gallardo, J., Jones, H. R. A., Lucas, P. W. L., Jenkins, J. S., Gomes, J., Folkes, S. L., Clarke, J. R. A. |
|---|---|
| Rok vydání: | 2013 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1093/mnras/sts685 |
| Popis: | We present a new sample of mid L to mid T dwarfs with effective temperatures of 1100 to 1700K selected from the UKIDSS Large Area Survey and confirmed with infrared spectra from X-Shooter/VLT. This effective temperature range is especially sensitive to the formation history of Galactic brown dwarfs and allows us to constrain the form of the sub-stellar birth rate, with sensitivity to differentiate between a flat (stellar like) birth rate, and an exponentially declining form. We present the discovery of 63 new L and T dwarfs from the UKIDSS LAS DR7, including the identification of 12 likely unresolved binaries, which form the first complete sub-set from our program, covering 495 sq degrees of sky, complete to J=18.1. We compare our results for this sub-sample with simulations of differing birth rates for objects of mass 0.10-0.03Msol and ages 1-10Gyrs. We find that the more extreme birth rates (e.g. a halo type form) can likely be excluded as the true form of the birth rate. In addition we find that although there is substantial scatter we find a preference for a mass function, with a power-law index, alpha in the range -1 < alpha < 0 that is consistent (within the errors) with the studies of late T dwarfs. Comment: 19 pages, 14 figures. Accepted for publication in MNRAS |
| Databáze: | arXiv |
| Externí odkaz: |
|