MACHO

           

Principal Investigator

Tim Axelrod

Mount Stromlo and Siding Spring Observatories

The MACHO project is examining the distribution of dark matter in our galaxy. The stars in the Large and Small Magellanic Clouds ( two small galaxies near our own ) and the stars in the galactic bulge (the centre of our galaxy) are being monitored over a period of several years for instances of "microlensing". Microlensing occurs when a dark-matter object ( eg: a dead star or a black hole ) passes in front of the star, resulting in an increase in the apparent brightness of the star due to the efect of the dark object's gravity on the star's light. Microlensing is an effect predicted by the Theory of Relativity, and the MACHO project is the first to actually observe this effect. By detecting multiple instances of microlensing, the project is able to construct a model of the overall distribution of this dark matter in our galaxy. The name MACHO is an acronym for MAssive Compact Halo Object, a more precise name for the dark matter objects.    

Co-Investigators

     

Jon Smillie

Mount Stromlo and Siding Spring Observatories

     

Projects

MDSS
     
         

 

 

How did the MDSS help in archieving the project's results?

The MACHO project generates significant amounts of both raw and reduced data. To date, MACHO has collected almost 70,000 images of 74Mb each, and is expected to collect up to another 20,000 before the project terminates. Reduced data accounts for a further 10 - 20% on top of the raw image data volumes. It is crucial to the project's success that all data is stored safely in a readily accessable location. The MDSS has proven an excellent solution to these requirements. The MDSS is now the prime repository for the raw MACHO images and approximately half the reduced data. Using the MDSS negates the inconvenience and reliability problems associated with other media such as magnetic tape, whilst at the same time enhancing data availability.

Publications

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, K. H. Cook, K. C. Freeman, K. Griest, M. J. Lehner, S. L. Marshall, D. Minniti, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, C. W. Stubbs, W. Sutherland, A. Tomaney, T. Vandehei, and D.L. Welch,(The MACHO Collaboration), Is the Large Magellanic Cloud Microlensing Due to an Intervening Dwarf Galaxy? submitted to the ApJ.


           
- Appendix A

 
           

       

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, K. H. Cook, K. C. Freeman, K. Griest, J. Guern, M. J. Lehner, S. L. Marshall, D. Minniti, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, W. Sutherland, and D. L. Welch,(The MACHO Collaboration),The MACHO Project Large Magellanic Cloud Variable Star Inventory. III. Multimode RR Lyrae Stars, Distance to the Large Magellanic Cloud, and Age of the Oldest Stars, ApJ, 482, 89 (1997)

C. Alcock, R. A. Allsman, D. R. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, P. A. Charles, K. H. Cook, K. C. Freeman, K. Griest, J. Guern, M. J. Lehner, M. Livio, S. L. Marshall, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, K. A. Southwell, C. W. Stubbs, and W. Sutherland (The MACHO Collaboration),The X-ray off-state of the supersoft source CAL 83 and its interpretation, MNRAS, 286, 483 (1997)

C. Alcock, R. A. Allsman, D. Alves, T. S. Axelrod, D. P. Bennett, K. H. Cook, K. C. Freeman, K. Griest, J. Guern, M. J. Lehner, S. L. Marshall, H. S. Park, S. Perlmutter, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, C. W. Stubbs, and W. Sutherland (The MACHO Collaboration), The MACHO Project: 45 Candidate Microlensing Events from the First-Year Galactic Bulge Data, ApJ, 479, 119 (1997)

C. Alcock, R. A. Allsman, D. Alves, T.S. Axelrod, D.P. Bennett, P.A. Charles, K.H. Cook, D. O'Donoghue, K.C. Freeman, K. Griest, J. Guern, M. J. Lehner, M. Livio, S. L. Marshall, D. Minniti, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, K. A. Southwell, C. W. Stubbs, W. Sutherland and D. L. Welch (The MACHO Collaboration), Optical photometry of the eclipsing Large Magellanic Cloud supersoft source, CAL 87, MNRAS, 287, 699 (1997)

C. Alcock, R. A. Allsman, D. Alves, T. S. Axelrod, A. C. Becker, D. P. Bennett, K. H. Cook, K. C. Freeman, K. Griest, J. Guern, M. J. Lehner, S. L. Marshall, D. Minniti, B. A. Peterson, M. R. Pratt, P. J. Quinn, A. W. Rodgers, C. W. Stubbs, W. Sutherland and D. L. Welch (The MACHO Collaboration), MACHO Project Photometry of RR Lyrae Stars in the Sagittarius Dwarf Galaxy, ApJ, 474, 217 (1997).

       
Appendix A -