Counting Mass with Gaia: Mass Density of Stars and Stellar Remnants in the Solar Neighborhood

Abstract In the light of new full-sky surveys, many attempts to create a consistent Galactic model were made. The main interest is to estimate the still poorly understood dark matter content. However, the results vary depending on methodology, assumptions, and baryonic distribution used. To understand this discrepancy, we take the first step by estimating the model-free local mass density of stars and stellar remnants. We use a complete sample from the Gaia Catalogue of Nearby Stars within 100 pc from the Sun, together with the data on the sample of the white dwarfs and the recent estimate of the neutron star concentration in the solar neighborhood. After correction for unresolved binary stars and accounting for missing low-mass stars, we find that the local mass density of stars and stellar remnants in the solar neighborhood is <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>ρ</mml:mi> <mml:mn>100</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.04</mml:mn> <mml:msubsup> <mml:mn>0</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.006</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.012</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mi>M</mml:mi> <mml:mrow> <mml:mo>⊙</mml:mo> <mml:mspace width="0.25em"/> </mml:mrow> </mml:msub> <mml:msup> <mml:mi>pc</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> with a Kroupa initial mass function (IMF) and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mi>ρ</mml:mi> <mml:mn>100</mml:mn> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.03</mml:mn> <mml:msubsup> <mml:mn>7</mml:mn> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.006</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.012</mml:mn> </mml:mrow> </mml:msubsup> <mml:mspace width="0.25em"/> <mml:msub> <mml:mi>M</mml:mi> <mml:mrow> <mml:mo>⊙</mml:mo> <mml:mspace width="0.25em"/> </mml:mrow> </mml:msub> <mml:msup> <mml:mi>pc</mml:mi> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3</mml:mn> </mml:mrow> </mml:msup> </mml:math> with a Chabrier IMF.