3 years ago

# The Star Formation Rate in the Gravoturbulent Interstellar Medium.

Blakesley Burkhart

We analytically determine the star formation rate (SFR) based on a piecewise power law and lognormal probability distribution function (PDF) of density in giant molecular clouds. This is in contrast to previous analytic SFR models that use purely lognormal density PDFs. Low density gas resides in the lognormal portion of the PDF. Gas becomes gravitationally unstable past a critical density ($\rho_{crit}$), and the PDF begins to forms a power law. As the collapse of the cloud proceeds, the transitional density ($\rho_t$) between the lognormal and power law portions of the PDF moves towards lower-density while the slope of the power law ($\alpha$) becomes increasingly shallow. The star formation rate per free-fall time is calculated via an integral over the lognormal from $\rho_{crit}$ to $\rho_t$ and an integral over the power law from $\rho_t$ to infinity. As $\alpha$ becomes shallower the SFR increases beyond the expected values calculated from a lognormal density PDF. We show that the star formation efficiency per free fall time in local molecular clouds increases with shallower PDF power law slopes, in agreement with our model. The approach presented here yields star formation rates in good agreement with both local GMCs and extragalactic observations. Our model can explain why star formation is spatially and temporally variable within a cloud and can accelerate and why the depletion times observed in local and extragalactic giant molecular clouds vary. Our model can explain both star-bursting and quiescent star-forming systems without the need to invoke extreme variations in the local interstellar environment.

Publisher URL: http://arxiv.org/abs/1801.05428

DOI: arXiv:1801.05428v1

You might also like
Discover & Discuss Important Research

Keeping up-to-date with research can feel impossible, with papers being published faster than you'll ever be able to read them. That's where Researcher comes in: we're simplifying discovery and making important discussions happen. With over 19,000 sources, including peer-reviewed journals, preprints, blogs, universities, podcasts and Live events across 10 research areas, you'll never miss what's important to you. It's like social media, but better. Oh, and we should mention - it's free.

Researcher displays publicly available abstracts and doesn’t host any full article content. If the content is open access, we will direct clicks from the abstracts to the publisher website and display the PDF copy on our platform. Clicks to view the full text will be directed to the publisher website, where only users with subscriptions or access through their institution are able to view the full article.