Day 1057

Monday.


1602.08098
Hubble space telescope observations of the host galaxies and environments of calcium-rich supernovae
Lyman, et al

Ca-rich SNe explosions sites have galactocentric offset distribution strongly skewed to very large offsets (~1/3 >20 kpc), meaning they do not trace the stellar light of their hosts.  No detection of host system of 5 nearby Ca-rich SNe.  In this case the offset distribution is most readily explained as a signature of high-velocity progenitor systems that have travelled significant distances before exploding.


1602.08108
Neutrino mass without cosmic variance
LoVerde

Measuring the absolute scale of the neutrino masses is one of the most exciting opportunities available with near-term cosmological datasets.  Two quantities that are sensitive to neutrino mass, scale-dependent halo bias b(k) and the linear growth parameter f(k) inferred from redshift-space distortions, can be measured without cosmic variance.  Unlike the amplitude of the matter power spectrum, which always has a finite error, the error on b(k) and f(k) continues to decrease as the number density of tracers increases.  This paper presents forecasts for statistics of galaxy and lensing fields that are sensitive to neutrino mass via b(k) and f(k).  The constraints on neutrino mass from the auto- and cross-power spectra of spectroscopic and photometric galaxy samples are weakened by scale-dependent bias unless a very high density of tracers is available.  In the high density limit, using multiple tracers allows cosmic variance to be beaten and the forecasted errors on neutrino mass shrink dramatically.  In practice, beating the cosmic variance errors on neutrino mass with b(k) will be a challenge, but this signal is nevertheless a new probe of neutrino effects on structure formation that is interesting in its own right.


1602.08430
Neutrino footprint in large scale structure
Jimenez, Pena-Garay, Verde

Recent constrains on the sum of neutrino masses inferred by analyzing cosmological data, show that detecting a non-zero neutrino mass is within reach of forthcoming cosmological surveys, implying a direct determination of the absolute neutrino mass scale.  The measurement relies on constraining the shape of the matter power spectrum below the neutrino free streaming scale: massive neutrinos erase power at thesis scales.  Detection of a lack of small-scale power, however, could also be due to a host of other effects.  It is therefore of paramount importance to validate neutrinos as the source of power suppression at small scales.  Show that, independent on hierarchy, neutrinos always show a footprint on large, linear scales; the exact location and properties can be related to the measured power suppression (an astrophysical measurement) and atmospheric neutrinos mass spitting (a neutrino oscillation experiment measurement).  This feature can not be easily mimicked by systematic uncertainties or modifications in the cosmological model.  The measurement of such a feature, up to 1% relative change in the power spectrum, is a smoking gun for confirming the determination of the absolute neutrino mass scale from cosmological observations.  It also demonstrates the synergy of astrophysics and particle physics experiments.