A dynamical measure of the black hole mass in a quasar 11 billion years ago

Tight relationships exist in the local Universe between the central stellar properties of galaxies and the mass of their supermassive black hole (SMBH)1-3. These suggest that galaxies and black holes co-evolve, with the main regulation mechanism being energetic feedback from accretion onto the black hole during its quasar phase4-6. A crucial question is how the relationship between black holes and galaxies evolves with time; a key epoch to examine this relationship is at the peaks of star formation and black hole growth 8-12 billion years ago (redshifts 1-3)7. Here we report a dynamical measurement of the mass of the black hole in a luminous quasar at a redshift of 2, with a look back in time of 11 billion years, by spatially resolving the broad-line region (BLR). We detect a 40-μas (0.31-pc) spatial offset between the red and blue photocentres of the Hα line that traces the velocity gradient of a rotating BLR. The flux and differential phase spectra are well reproduced by a thick, moderately inclined disk of gas clouds within the sphere of influence of a central black hole with a mass of 3.2 × 108 solar masses. Molecular gas data reveal a dynamical mass for the host galaxy of 6 × 1011 solar masses, which indicates an undermassive black hole accreting at a super-Eddington rate. This suggests a host galaxy that grew faster than the SMBH, indicating a delay between galaxy and black hole formation for some systems.

Evaluation of human IgG subclass assays on Beckman array

Automated immunonephelometric assays were developed to measure human IgG subclasses in serum, on the Beckman Array Protein System (APSR), with sheep antihuman IgG subclass antisera. The interassay imprecision was judged to be satisfactory in each case (CV: IgG1: 2.3%; IgG2: 2.9%; IgG3: 4.0% and IgG4 5.4%). The standard curves were found to be linear in the ranges 1.5-30.0 g/L for IgG1, 1.5-15.0 g/L for IgG2, 0.1-1.0 g/L for IgG3 and 0.1-1.0 g/L for IgG4. The lower limit for quantification of the immunephelometric assays was 0.5 g/L for IgG1, 0.04 g/L for IgG2, 0.06 g/L for IgG3 and 0.03 g/L for IgG4. We found no antigen excess to at least 60.0 g/L for IgG1 and IgG2, 3.5 g/L for IgG3 and 2.0 g/L for IgG4. Nephelometric results correlated with those of radial immunodiffusion (r = 0.96 for IgG1, r = 0.93 for IgG2, r = 0.90 for IgG3 and r = 0.96 for IgG4). The reaction monitored by the Beckman Array Protein System is easy to perform, rapid and precise. The performance makes the immunonephelometric method suitable for the determination of IgG subclass concentrations in routine analysis.