Liberal Education: “Learning to Learn”

When Sam Schuman and Anne Ponder recruited Chris Dahl and me to join them in developing an “Undergraduate Summit” which might bring together representatives of the major higher education associations, they billed our roles as “conversation starters.” I hope our remarks do just that, not offering fixed conclusions but sparking conversation among those who’ve joined us at the table in Chicago and among those who might become acquainted with the Summit later on. It is more than the accident of friendship that brought us together to get a larger conversation underway. Though all four of us are now leading college and university campuses of different kinds, we came from Honors program backgrounds, and this has colored our thoughts and perhaps even explains why we believe that a broader conversation about undergraduate education today is important. Ostensibly, Honors programs (or, increasingly, “colleges”) are meant to enrich, to challenge, and to meet the differing needs for intellectual stimulation among the members of diverse student bodies. But I think that few of us who have been involved in Honors education have failed to observe that in too many instances they seem intended to “salvage” the quality of an undergraduate degree for a fortunate minority—to provide (for at least those chosen and electing to take part) engaged, participatory learning, close interaction with “real” professors, intellectual community, and opportunities to try a hand at independent scholarship. Where this is, in fact, the case, it is a sad commentary on the state of a baccalaureate education—where it takes a “special” program to deliver to some students what ought to be in the experience of all. To note this takes nothing away from the dedicated Honors program administrators and faculty who conduct the programs. It only recognizes that in such settings they are swimming against the tide in their home institutions rather than with it, beating against the current for the best of reasons

A Spectroscopically Confirmed Excess of 24 micron Sources in a Super Galaxy Group at z=0.37: Enhanced Dusty Star Formation Relative to the Cluster and Field Environment

To trace how dust-obscured star formation varies with environment, we compare the fraction of 24 micron sources in a super galaxy group to the field and a rich galaxy cluster at z~0.35. We draw on multi-wavelength observations that combine Hubble, Chandra, and Spitzer imaging with extensive optical spectroscopy (>1800 redshifts) to isolate galaxies in each environment and thus ensure a uniform analysis. We focus on the four galaxy groups in supergroup 1120-12 that will merge to form a galaxy cluster comparable in mass to Coma. We find that 1) the fraction of supergroup galaxies with SFR(IR)>3 Msun/yr is four times higher than in the cluster (32% vs. 7%); 2) the supergroup's infrared luminosity function confirms that it has a higher density of IR members compared to the cluster and includes bright IR sources not found in galaxy clusters at z<0.35; and 3) there is a strong trend of decreasing IR fraction with increasing galaxy density, i.e. an IR-density relation, not observed in the cluster. These dramatic differences are surprising because the early-type fraction in the supergroup is already as high as in clusters, i.e. the timescales for morphological transformation cannot be strongly coupled to when the star formation is completely quenched. The supergroup has a significant fraction (~17%) of luminous, low-mass, IR members that are outside the group cores (R>0.5 Mpc); once their star formation is quenched, most will evolve into faint red galaxies. Our analysis indicates that the supergroup's 24 micron population also differs from that in the field: 1) despite the supergroup having twice the fraction of E/S0s as the field, the fraction of IR galaxies is comparable in both environments, and 2) the supergroup's IR luminosity function has a higher L(IR)* than that previously measured for the field.Comment: Accepted by the Astrophysical Journa

Comparison of star formation rates from Halpha and infrared luminosities as seen by Herschel

We empirically test the relation between the SFR(LIR) derived from the infrared luminosity, LIR, and the SFR(Ha) derived from the Ha emission line luminosity using simple conversion relations. We use a sample of 474 galaxies at z = 0.06 - 0.46 with both Ha detection (from 20k zCOSMOS survey) and new far-IR Herschel data (100 and 160 {\mu}m). We derive SFR(Ha) from the Ha extinction corrected emission line luminosity. We find a very clear trend between E(B - V) and LIR that allows to estimate extinction values for each galaxy even if the Ha emission line measurement is not reliable. We calculate the LIR by integrating from 8 up to 1000 {\mu}m the SED that is best fitting our data. We compare SFR(Ha) with the SFR(LIR). We find a very good agreement between the two SFR estimates, with a slope of m = 1.01 \pm 0.03 in the SFR(LIR) vs SFR(Ha) diagram, a normalization constant of a = -0.08 \pm 0.03 and a dispersion of sigma = 0.28 dex.We study the effect of some intrinsic properties of the galaxies in the SFR(LIR)-SFR(Ha) relation, such as the redshift, the mass, the SSFR or the metallicity. The metallicity is the parameter that affects most the SFR comparison. The mean ratio of the two SFR estimators log[SFR(LIR)/SFR(Ha)] varies by approx. 0.6 dex from metal-poor to metal-rich galaxies (8.1 < log(O/H) + 12 < 9.2). This effect is consistent with the prediction of a theoretical model for the dust evolution in spiral galaxies. Considering different morphological types, we find a very good agreement between the two SFR indicators for the Sa, Sb and Sc morphologically classified galaxies, both in slope and normalization. For the Sd, irregular sample (Sd/Irr), the formal best-fit slope becomes much steeper (m = 1.62 \pm 0.43), but it is still consistent with 1 at the 1.5 sigma level, because of the reduced statistics of this sub-sample.Comment: 13 pages, 11 figures, accepted for publication in MNRA