Abstract
Recent work has found evidence for a difference in the bias and dark matter
halo masses of WISE-selected obscured and unobscured quasars, implying a
distinction between these populations beyond random line-of-sight effects.
However, the significance of this difference in the most up-to-date
measurements is relatively weak, at $\sim$2$\sigma$ for individual measurements
but bolstered by agreement from different techniques, including angular
clustering and cross-correlations with cosmic microwave background (CMB)
lensing maps. Here, we expand the footprint of previous work, aiming to improve
the precision of both methods. In this larger area we correct for position
dependent selection effects, in particular fluctuations of the WISE-selected
quasar density as a function of Galactic latitude. We also measure the
cross-correlation of the obscured and unobscured samples and confirm that they
are well-matched in redshift, both centred at $z=1$. Combined with very similar
detection fractions and magnitude distributions in the long-wavelength WISE
bands, this redshift match strongly supports the fact that IR selection
identifies obscured and unobscured quasars of similar bolometric luminosity.
Finally, we perform cross-correlations with confirmed spectroscopic quasars,
again confirming the results from other methods --- obscured quasars reside in
haloes a factor of 3 times more massive than unobscured quasars. This
difference is significant at the $\sim$5$\sigma$ level when the measurements
are combined, strong support for the idea that obscuration in at least some
quasars is tied to the larger environment, and may have an evolutionary
component.
Description
[1705.05306] The characteristic halo masses of half-a-million WISE-selected quasars
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