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Using group catalogs from the SDSS DR7, we attempt to measure galacticconformity in the local universe. We measure the quenched fraction of neighborgalaxies around isolated primary galaxies, dividing the isolated sample intostar-forming and quiescent objects. We restrict our measurements to scales $>1$Mpc to probe the correlations between the formation histories of distincthalos. Over the stellar mass range $10^{9.7} \le M_\ast/M_\odot \le 10^{10.9}$,we find minimal statistical evidence for conformity. We further compare thesedata to predictions of the halo age-matching model, in which the oldestgalaxies are associated with the oldest halos at fixed $M_\ast$. For modelswith strong correlations between halo and stellar age, the conformity signal istoo large to be consistent with the data. For weaker implementations ofage-matching, galactic conformity is not a sensitive diagnostic of haloassembly bias, and would not produce a detectable signal in SDSS data. Wereproduce the results of Kauffmann et al 2013, in which the star formationrates of neighbor galaxies are significantly reduced around primary galaxieswhen the primaries are themselves low star formers. However, we find thisresult is mainly driven by contamination in the isolation criterion, when usingour group catalog to remove the small fraction of satellite galaxies in thesample, the conformity signal largely goes away. Lastly, we show that smallconformity signals, i.e., 2-5% differences in the quenched fractions ofneighbor galaxies, can be produced by mechanisms other than halo assembly bias.For example, if passive galaxies occupy more massive halos than star forminggalaxies of the same stellar mass, a conformity signal that is consistent withrecent measurements from PRIMUS (Berti et al 2016) can be produced.

Halo Histories vs. Galaxy Properties at z=0 II: Large-Scale Galactic Conformity