SIMBAD references

We compare the results of Grimm, Gilfanov & Sunyaev and Ranalli, Comastri & Seti on the L_X-SFR (X-ray luminosity-star formation rate) relation in normal galaxies. Based on the L_X-stellar mass dependence for low-mass X-ray binaries (LMXBs), we show that low-SFR (≲1 M_☉/yr) galaxies in the Ranalli et al. sample are contaminated by the X-ray emission from LMXBs, unrelated to the current star formation activity.

However, the most important conclusion from our comparison is that, after the data are corrected for the `LMXB contamination', the two data sets become consistent with each other, despite differences in their content, variability effects, adopted source distances, X-ray fluxes and SFR determinations, and also in the cosmological parameters used in interpreting the Hubble Deep Field North (HDF-N) data. They also agree well, both in the low- and high-SFR regimes, with the predicted L<sub>X</sub>-SFR dependence derived from the parameters of the `universal' high-mass X-ray binary (HMXB) luminosity function. This encouraging result emphasizes the potential of the X-ray luminosity as an independent SFR indicator for normal galaxies.