What Gaia can reveal about the matter distribution in the Milky Way
(2014) In Lund Observatory Examensarbeten ASTM31 20141Lund Observatory - Undergoing reorganization
Department of Astronomy and Theoretical Physics - Undergoing reorganization
- Abstract
- Context. With the goal to accurately map about a billion of the Milky Way stars, the astrometric satellite Gaia was launched in December 2013. Its high precision and sensitivity will lead to better understanding of the Galactic structure and evolution. Also, it will be possible to probe the matter distribution in the Galaxy.
Aims. To study how well the Galactic matter distribution can be determined from Gaia data, using a direct application of the Jeans equations.
Methods. An expression for mass density applicable to collisionless gravitational systems can be found by combining the second Jeans equations with Poisson’s equation. Through orbit integration of a few million stars in a potential model of the Milky Way, astrometric data... (More) - Context. With the goal to accurately map about a billion of the Milky Way stars, the astrometric satellite Gaia was launched in December 2013. Its high precision and sensitivity will lead to better understanding of the Galactic structure and evolution. Also, it will be possible to probe the matter distribution in the Galaxy.
Aims. To study how well the Galactic matter distribution can be determined from Gaia data, using a direct application of the Jeans equations.
Methods. An expression for mass density applicable to collisionless gravitational systems can be found by combining the second Jeans equations with Poisson’s equation. Through orbit integration of a few million stars in a potential model of the Milky Way, astrometric data were simulated. Taking into account extinction using a smooth model based on hydrogen observations, measurement errors expected from Gaia were generated for the chosen tracer stars (M-giants). Applying a grid covering the region of the model set by the magnitude limits of Gaia, the mass density was estimated in every grid-bin and thus resolution was achieved.
Results. I find that within the region limited by 5.5 < R < 12 kpc and |z| < 200 pc, the mass density can be estimated with better than 35 % accuracy. Within the smaller region limited by 6 < R < 9 kpc and |z| < 50 pc, the estimation error has decreased to a few percent and in the Solar neighbourhood it will be possible to probe the matter distribution with about one percent precision. Both the regions mentioned cover a large part of the Perseus spiral arm and spans over different locations where the individual components of the Galaxy are prominent.
Conclusions. The extensive regions probed with this method make it possible to determine the large-scale structure of the Milky Way, including e.g., more accurately determined radial and vertical scale lengths. It will be possible to improve the estimation of the local mass density by about a factor ten compared to the current values. The precision of the method allows to test different scenarios for the distribution of dark matter in the disk and elsewhere in the Galaxy. (Less)
Please use this url to cite or link to this publication:
http://lup.lub.lu.se/student-papers/record/4586626
- author
- Götberg, Ylva LU
- supervisor
-
- Lennart Lindegren LU
- David Hobbs LU
- organization
- course
- ASTM31 20141
- year
- 2014
- type
- H2 - Master's Degree (Two Years)
- subject
- publication/series
- Lund Observatory Examensarbeten
- report number
- 2014-EXA81
- language
- English
- id
- 4586626
- date added to LUP
- 2014-08-11 15:15:10
- date last changed
- 2014-08-11 15:15:10
@misc{4586626,
abstract = {{Context. With the goal to accurately map about a billion of the Milky Way stars, the astrometric satellite Gaia was launched in December 2013. Its high precision and sensitivity will lead to better understanding of the Galactic structure and evolution. Also, it will be possible to probe the matter distribution in the Galaxy.
Aims. To study how well the Galactic matter distribution can be determined from Gaia data, using a direct application of the Jeans equations.
Methods. An expression for mass density applicable to collisionless gravitational systems can be found by combining the second Jeans equations with Poisson’s equation. Through orbit integration of a few million stars in a potential model of the Milky Way, astrometric data were simulated. Taking into account extinction using a smooth model based on hydrogen observations, measurement errors expected from Gaia were generated for the chosen tracer stars (M-giants). Applying a grid covering the region of the model set by the magnitude limits of Gaia, the mass density was estimated in every grid-bin and thus resolution was achieved.
Results. I find that within the region limited by 5.5 < R < 12 kpc and |z| < 200 pc, the mass density can be estimated with better than 35 % accuracy. Within the smaller region limited by 6 < R < 9 kpc and |z| < 50 pc, the estimation error has decreased to a few percent and in the Solar neighbourhood it will be possible to probe the matter distribution with about one percent precision. Both the regions mentioned cover a large part of the Perseus spiral arm and spans over different locations where the individual components of the Galaxy are prominent.
Conclusions. The extensive regions probed with this method make it possible to determine the large-scale structure of the Milky Way, including e.g., more accurately determined radial and vertical scale lengths. It will be possible to improve the estimation of the local mass density by about a factor ten compared to the current values. The precision of the method allows to test different scenarios for the distribution of dark matter in the disk and elsewhere in the Galaxy.}},
author = {{Götberg, Ylva}},
language = {{eng}},
note = {{Student Paper}},
series = {{Lund Observatory Examensarbeten}},
title = {{What Gaia can reveal about the matter distribution in the Milky Way}},
year = {{2014}},
}