The Top 12 of 2012

8. Weighing the Dark Matter in Galaxy Clusters with Hubble

Why it is important: The distribution of dark matter traces the formation of structure in the universe. Galaxy clusters represent some of the most massive dark matter groupings we can observe, and so determining how their mass is distributed lets us probe how the largest structures formed. Because such massive structures are rare, they can also be a powerful probe of cosmological models.

This figure shows four strongly-lensing galaxy clusters in a sample of 25 which will be used to determine the dark matter distribution on small and large scales (tens of kiloparsecs to megaparsecs) in cluster haloes. In addition to testing models for the concentration of dark matter in haloes (see #6), this project will also yield samples of highly lensed z > 7 galaxies which probe the epoch of reionization (see #12). Finally, by spreading these observations over multiple epochs, this project will further constitute an effective search for z > 1 type Ia supernovae, which are important for understanding how dark energy evolved (see #2). (Figure 12 of Postman et al.)

Next: (#7) Putting a New Spin on Stellar Models: A New Treatment of Mass Loss and Rotation for Stellar Evolution

Previous: (#9) Stars in Old Galaxies–They are NOT Just Like Us: The Masses of Stars at Birth May Depend on Environment

About Betsy Mills

I am a 22nd-grader at UCLA, working with Mark Morris and spending the year at the MPIA in Heidelberg finishing my thesis. I like molecules in space, radio telescopes, the extreme center of our galaxy, getting to look at things no-one else has ever seen before, solving puzzles, and finding creative ways to survive graduate school


  1. Hi Betsy:

    Just a note– it looks like the arXiv link that you have on the first page of this article does not link to the title you provide.

    The link looks like it goes here:

    “How supernova feedback turns dark matter cusps into cores”

    instead of here:

    “Keck Spectroscopy of Faint 3<z<8 Lyman Break Galaxies:- Evidence for a Declining Fraction of Emission Line Sources In the Redshift Range 6<z<8"


    • Ah, actually the links are just switched–


      • Thanks Dave! The links are now fixed.

  2. Fascinating articles! But counting citations seriously distorts what astronomy is about. Because most young astronomers today work in observational cosmology, 10/12 papers are on that topic, the most glamorous frontier. But 10/12 of the most significant new papers of 2012 (selected some other way) paint a certainly much broader canvas, and reflect the amazing scope of astronomical research!
    Only the search for new planets (another glamour topic) and new calculations of the evolution of rotating stars in the HR diagram (a classic issue in stellar astronomy) penetrated the top twelve. So much more was missing!
    Nonetheless, an interesting citation poll.

    • Yes, I had the mass-to-light ratio section entirely backward; this is now corrected (and consistent with the linked astrobite). Thank you!!


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