We present a statistical X-ray study of spiral galaxies in the Hubble Deep Field-North and its Flanking Fields using the Chandra Deep Field North 1 Ms dataset .
We find that \approx L ^ { * } galaxies with 0.4 \lower 2.15 pt \hbox { $ \buildrel < \over { \sim } $ } z \lower 2.15 pt \hbox { $ % \buildrel < \over { \sim } $ } 1.5 have ratios of X-ray to B -band luminosity similar to those in the local Universe , although the data indicate a likely increase in this ratio by a factor of \approx 2 –3 .
We have also determined that typical spiral galaxies at 0.4 \lower 2.15 pt \hbox { $ \buildrel < \over { \sim } $ } z \lower 2.15 pt \hbox { $ % \buildrel < \over { \sim } $ } 1.5 should be detected in the 0.5–2 keV band in the flux range ( 3 –6 ) \times 10 ^ { -18 } erg cm ^ { -2 } s ^ { -1 } .