Probing Individual Star Forming Regions Within Strongly Lensed Galaxies at z > 1

Star formation occurs on physical scales corresponding to individual star forming regions, typically of order ~100 parsecs in size, but current observational facilities cannot resolve these scales within field galaxies beyond the local universe. However, the magnification from strong gravitational lensing allows us to measure the properties of these discrete star forming regions within galaxies in the distant universe. New results from multi-wavelength spectroscopic studies of a sample of extremely bright, highly magnified lensed galaxies are revealing the complexity of star formation on sub-galaxy scales during the era of peak star formation in the universe. We find a wide range of properties in the rest-frame UV spectra of individual galaxies, as well as in spectra that originate from different star forming regions within the same galaxy. Large variations in the strengths and velocity structure of Lyman-alpha and strong P Cygni lines such as C IV, and MgII provide new insights into the astrophysical relationships between extremely massive stars, the elemental abundances and physical properties of the nebular gas those stars ionize, and the galactic-scale outflows they power.Comment: 4 pages, 3 figures. To be published in the Proceedings of IAU Symposium 309. For more details and closely related work see also arXiv:1310.6695 and arXiv:1406.335

Searching for Cooling Signatures in Strong Lensing Galaxy Clusters: Evidence Against Baryons Shaping the Matter Distribution in Cluster Cores

The process by which the mass density profile of certain galaxy clusters becomes centrally concentrated enough to produce high strong lensing (SL) cross-sections is not well understood. It has been suggested that the baryonic condensation of the intra-cluster medium (ICM) due to cooling may drag dark matter to the cores and thus steepen the profile. In this work, we search for evidence of ongoing ICM cooling in the first large, well-defined sample of strong lensing selected galaxy clusters in the range 0.1 < z < 0.6. Based on known correlations between the ICM cooling rate and both optical emission line luminosity and star formation, we measure, for a sample of 89 strong lensing clusters, the fraction of clusters that have [OII]3727 emission in their brightest cluster galaxy (BCG). We find that the fraction of line-emitting BCGs is constant as a function of redshift for z > 0.2 and shows no statistically significant deviation from the total cluster population. Specific star formation rates, as traced by the strength of the 4000 angstrom break, D_4000, are also consistent with the general cluster population. Finally, we use optical imaging of the SL clusters to measure the angular separation, R_arc, between the arc and the center of mass of each lensing cluster in our sample and test for evidence of changing [OII] emission and D_4000 as a function of R_arc, a proxy observable for SL cross-sections. D_4000 is constant with all values of R_arc, and the [OII] emission fractions show no dependence on R_arc for R_arc > 10" and only very marginal evidence of increased weak [OII] emission for systems with R_arc < 10". These results argue against the ability of baryonic cooling associated with cool core activity in the cores of galaxy clusters to strongly modify the underlying dark matter potential, leading to an increase in strong lensing cross-sections.Comment: 9 Pages, 5 Figures, 1 Tabl

Equality Opportunity: Marriage Litigation and Iowa’s Equal Protection Law

Discrimination claims against longstanding rules invite the public and the courts to rethink the status quo and address overarching legal and social commitments to equality together with questions specific to the case at hand. Lawsuits seeking marriage rights for same-sex couples quintessentially illustrate this multilayered nature of law reform litigation, as the debates they provoke focus not only on the rights of same-sex couples but also on the meaning of marriage and the meaning of equality more generally. While few other than lawyers, judges, and perhaps some reporters actually read the equal protection and due process arguments that the presiding court will consider, many community members where marriage litigation is taking place become fully engaged in debating the equality and fundamental rights questions implicated by the legal claims. This degree of popular attention certainly exists in Iowa, where talk of gay couples marrying took center stage even before a lawsuit was filed in the Iowa district court in 2005. The suit, which was brought by six lesbian and gay couples and eventually joined by some of the couples’ children, is one of many marriage equality suits to be filed in recent years and is the first to be filed in the Midwest. Yet while the public debate may be wide-ranging, it typically misses the ways in which the lawsuit may have long-term consequences for a state’s equality jurisprudence that extend well beyond marriage. In Iowa, specifically, while Varnum v. Brien focuses directly on marriage equality, the case also engages an ongoing conversation among the state’s courts about how Iowa’s equality guarantees should be enforced. This essay introduces an amicus brief filed with the Iowa Supreme Court on behalf of three Iowa constitutional law scholars that addresses these broad questions about the future of Iowa equal protection law. In publishing the brief with the University of Iowa College of Law’s Journal of Gender, Race & Justice, we aim to show why, both in Iowa and around the country, courts would be better off embracing a single standard of equal protection review rather than the ossified and often ineffective federal tiered approach. By highlighting the brief’s implications for issues beyond marriage, we also aim to illustrate the point that law reform litigation, especially regarding contested social issues, often implicates not only the specific claim before the court but also other far-reaching questions about the jurisprudential status quo