The star formation rate in disc galaxies: thresholds and dependence on gas amount

By S. Boissier, N. Prantzos, A. Boselli, G. Gavazzi. 2003

176 citations recorded by the source corpus.

We reassess the applicability of the Toomre criterion in galactic discs and we study the local star formation law in 16 disc galaxies for which abundance gradients are published. The data we use consist of stellar light profiles, atomic and molecular gas (deduced from CO with a metallicity-dependent conversion factor), star formation rates (from Ha emissivities), metal-licities, dispersion velocities and rotation curves. We show that the Toomre criterion applies successfully to the case of the Milky Way disc, but it has limited success with the data of our sample; depending on whether or not the stellar component is included in the stability analysis, we find average values for the threshold ratio of the gas surface density to the critical surface density in the range 0.5-0.7. We also test various star formation laws proposed in the literature, i.e. either the simple Schmidt law or modifications of it, that take into account dynamical factors. We find only small differences among them as far as the overall fit to our data is concerned; in particular, we find that all three star formation laws (with parameters derived from the fits to our data) match observations in the Milky Way disc particularly well. In all cases we find that the exponent n of our best-fitting star formation rate has slightly higher values than in other recent works and we suggest several reasons that may cause that discrepancy.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/4cc6d602cfd8ce6f2c835cfb908ec1441a8934a3

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Citations in the corpus

Molecular Hydrogen and Global Star Formation Relations in Galaxies (2007, methodology): “While the slope of the spatially-resolved molecular gas SK relation is consistently measured to benmol ≈ 1.4 in the same systems, with a two-sigma variation ofnmol ∼ 1.2− 1.7 (Wong & Blitz 2002; Boissier et al. 2003; Heyer et al. 2004; Boissier et al. 2007; Kennicutt et al. 2007).”
MOLECULAR GAS AND STAR FORMATION IN NEARBY DISK GALAXIES (2013, methodology): “Rotation Velocities: Following L08 and Boissier et al. (2003) we work with a simple two-parameter fit to the rotation curve of each galaxy vrot (rgal) = vflat [ 1− exp (−rgal lflat )] (9) with vflat and lflat free parameters.”
EXTREMELY INEFFICIENT STAR FORMATION IN THE OUTER DISKS OF NEARBY GALAXIES (2010, methodology): “Inside r25, Leroy et al. (2008) found Qmedian ≈ 4 for the same methodology that we use here and Qmedian ≈ 2 considering a disk of gas and stars (also see Boissier et al. 2003; Yang et al. 2007).”
THE STAR FORMATION RATE AND GAS SURFACE DENSITY RELATION IN THE MILKY WAY: IMPLICATIONS FOR EXTRAGALACTIC STUDIES (2010, methodology): “…studies of SFR– gas relations on either global scales (Kennicutt 1989, 1998b) or using either radial (Martin & Kennicutt 2001; Wong & Blitz 2002; Boissier et al. 2003; Heyer et al. 2004; Komugi et al. 2005; Schuster et al. 2007) or point–by– point measurements (Kuno et al. 1995; Zhang et al.…”
Star Formation in the Milky Way and Nearby Galaxies (2012, background): “Early work on this problem (e.g., Kennicutt 1989; Martin & Kennicutt 2001; Boissier et al. 2003) was based on radial profiles in Hα, and some questions have been raised about whether these thresholds resulted from breakdowns in the SFR versus Hα calibration in low surface brightness regimes, as…”
THE STATE OF THE GAS AND THE RELATION BETWEEN GAS AND STAR FORMATION AT LOW METALLICITY: THE SMALL MAGELLANIC CLOUD (2011, background): “Several subsequent studies focused on the star formation law within galaxies, employing high resolution molecular and H I observations (Martin & Kennicutt 2001; Wong & Blitz 2002; Boissier et al. 2003).”
CIGALE: a python Code Investigating GALaxy Emission (2018, background): “This was done for example by Boissier et al. (2003), Buat et al. (2008) who related the SFH to the rotational velocity of the galaxy.”
THE STAR FORMATION EFFICIENCY IN NEARBY GALAXIES: MEASURING WHERE GAS FORMS STARS EFFECTIVELY (2008, unknown): “Yang et al. (2007) recently showed that Q stars+gas does an excellent job of predicting the location of star formation in the Large Magellanic Cloud and Boissier et al. (2003) showed that including stars improves the correspondence between Q and star formation in disk galaxies.”
REGULATION OF STAR FORMATION RATES IN MULTIPHASE GALACTIC DISKS: A THERMAL/DYNAMICAL EQUILIBRIUM MODEL (2010, unknown): “…the star formation rate with Σ, using either azimuthal averages over rings, or mapping with apertures down to <∼ kpc scales (e.g. Wong & Blitz 2002; Boissier et al. 2003, 2007; Heyer et al. 2004; Komugi et al. 2005; Schuster et al. 2007; Kennicutt et al. 2007; Dong et al. 2008; Bigiel et al.…”
FORMATION OF MASSIVE GALAXIES AT HIGH REDSHIFT: COLD STREAMS, CLUMPY DISKS, AND COMPACT SPHEROIDS (2009, background): “We note, however, that there are rare cases at low redshift of relatively gas-rich galaxies that somewhat resemble the perturbed clumpy appearance of the high-redshift SFGs (e.g., NGC 4303, Boissier et al. 2003).”
The effect of the environment on the Hi scaling relations (2011, methodology): “Briefly, the evolution of galaxies is traced using the multi-zone chemical and spectrophotometric model of Boissier & Prantzos (2000), updated with an empirically determined star formation law (Boissier et al. 2003) relating the star formation rate to the total gas surface densities.”
ENVIRONMENTAL DEPENDENCE OF THE KENNICUTT–SCHMIDT RELATION IN GALAXIES (2010, background): “In addition, there is a growing observational evidence that the KS relation is more complex than previously thought (Heyer et al. 2004; Boissier et al. 2003; Bigiel et al. 2008).”
Star Formation in NGC 5194 (M51a). II. The Spatially Resolved Star Formation Law (2007, background): “An analysis of radial profiles of 11 nearby spirals by Boissier et al. (2003) derived significantly steeper (N ∼ 2) Schmidt law indices; the difference in this case can be attributed to their use of a radially varying (metallicity-dependent) CO/H2 conversion factor (a constant factor was used in…”
Radial Variation of Attenuation and Star Formation in the Largest Late-Type Disks Observed with GALEX (2006, methodology): “…is correct, the origin of the threshold of star formation, largely debated on theoretical grounds (Toomre 1964; Quirk 1972; Wang & Silk 1994; Martin & Kennicutt 2001; Wong & Blitz 2002; Boissier et al. 2003; Schaye 2004) on the basis of Hα observations would be simply the lack of ionizing stars.”
ON THE EVOLUTION OF THE MOLECULAR GAS FRACTION OF STAR-FORMING GALAXIES (2011, background): “…calibration of CO luminosity to total gas mass in both low- and high-z galaxies have made interpretation of results challenging; even in the local Universe there is seen to be metallicity and luminosity dependence on the conversion (Boissier et al. 2003; Blitz et al. 2007; Komugi et al. 2010).”
The lifecycle of molecular clouds in nearby star-forming disc galaxies (2019, background): “…et al. 2010; Leroy et al. 2013; Kreckel et al. 2018; Kruijssen et al. 2019) as well as in low-density environments, such as in low surface brightness galaxies or in galaxy outskirts (e.g. Kennicutt 1989; Martin & Kennicutt 2001; Boissier et al. 2003; Bigiel et al. 2010; Goddard et al. 2010).”
MODELING MOLECULAR HYDROGEN AND STAR FORMATION IN COSMOLOGICAL SIMULATIONS (2008, result): “These results are also consistent with existing detailed studies of the Kennicutt-Schmidt relation in nearby galaxies with lower metallicities and surface densities (e.g., Boissier et al. 2003; Heyer et al. 2004, Wyder et al. 2008, in preparation).”
Star-formation laws in luminous infrared galaxies. New observational constraints on models (2011, background): “Alternatively, other forms of the star formation laws adduce the importance of including explicitlyglobal dynamical time scales tdyn (Elmegreen 1997; Silk 1997; Kennicutt 1998; Elmegreen 2002; Boissier et al. 2003; Tasker & Tan 2009; Tan 2010; Genzel et al. 2010).”