The stellar initial mass function and star formation in the galaxy
We use observational constraints on the galactic ionizing photon production, the surface mass distribution of field M dwarfs, and the mass distribution of brown dwarfs in clusters to produce an effective galactic initial mass function (IMF). We assume that the IMF can be expressed as the product of a smooth function of mass m (in units of MΘ),ψ (m), and a time dependent rate. We express the star formation rate per unit area per unit logarithmic mass interval as <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s1.jpg"><img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s8.jpg"><img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s2.jpg">/[dA dln m] <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s8.jpg"><img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s3.jpg" > or = <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s4.jpg">[l - exp - <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s7.jpg">]; for (m < m u ), with <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s5.jpg" > or = 0.8 (the asymptotic low-mass slope inferred from the mass distribution in young clusters at sub-stellar masses), Γ = 1.35 (the negative of the high-mass slope), m ch = 0.24 (producing a maximum at m max~ m ch), and m u = 120. For a disk age of 11 Gyr, the average value of the star formation rate per unit logarithmic mass interval at 1 MΘ at the solar circle is <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s6.jpg">620 kpc-2 Myr-1, and the ratio of the present to the mean SFR is b (t0 ) = 1.085, where t0 is the age of the disk.
| Main Authors: | , , |
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| Format: | Digital revista |
| Language: | English |
| Published: |
Sociedad Mexicana de Física
2006
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| Online Access: | http://www.scielo.org.mx/scielo.php?script=sci_arttext&pid=S0035-001X2006000900001 |
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| Summary: | We use observational constraints on the galactic ionizing photon production, the surface mass distribution of field M dwarfs, and the mass distribution of brown dwarfs in clusters to produce an effective galactic initial mass function (IMF). We assume that the IMF can be expressed as the product of a smooth function of mass m (in units of MΘ),ψ (m), and a time dependent rate. We express the star formation rate per unit area per unit logarithmic mass interval as <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s1.jpg"><img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s8.jpg"><img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s2.jpg">/[dA dln m] <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s8.jpg"><img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s3.jpg" > or = <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s4.jpg">[l - exp - <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s7.jpg">]; for (m < m u ), with <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s5.jpg" > or = 0.8 (the asymptotic low-mass slope inferred from the mass distribution in young clusters at sub-stellar masses), Γ = 1.35 (the negative of the high-mass slope), m ch = 0.24 (producing a maximum at m max~ m ch), and m u = 120. For a disk age of 11 Gyr, the average value of the star formation rate per unit logarithmic mass interval at 1 MΘ at the solar circle is <img width=32 height=32 src="../../../../../img/revistas/rmf/v52s3/a1s6.jpg">620 kpc-2 Myr-1, and the ratio of the present to the mean SFR is b (t0 ) = 1.085, where t0 is the age of the disk. |
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