GeminiFocus 2016 Year in Review | Page 32

Figure 17 . Three GMOS ( North and South ) spectra obtained at different times of the z = 2.47 quasar J0230 show the variability of the absorption features , especially the CIV near rest-frame wavelength 1550 Å . The spectra have been normalized based on measurements in the shaded regions . vations using the Gemini Multi-Object Spectrograph ( GMOS ) at both Gemini North and Gemini South show spectral changes over time in this case . At a redshift of z = 2.47 , the galaxy ’ s rest-frame ultraviolet emission appears at optical wavelengths , and broad CIV absorption is the key feature the team traced .
This exceptional example , called SDSS J023011.28 + 005913.6 or J0230 for short , is also interesting in showing a second strong component , with an outflow velocity around 40,000 kilometers per second . The multiple observations of the quasar at various times show variability ( on timescales as short as 10 days in the quasar rest frame ; Figure 17 ) and enable the team to rule out some simple models of bulk motion . Instead , they show that some more complex geometric configurations are consistent with the observations — namely a “ crossing disk ” model ( of a circular cloud that crosses a circular emitting region ) and “ flow tube ” ( where a spatially extended absorbing region passes in front of the emitting region ) for the faster and slower outflows , respectively .
Continued study of the larger sample of about 100 candidates may reveal more systematic characteristics of the broad absorption features and their origin . This work is featured on the Gemini website , and full results are published in Monthly Notices of the Royal Astronomical Society ( viewable here ).
30 GeminiFocus January 2017 | 2016 Year in Review