18,921 research outputs found
The Nucleus of Main-Belt Comet P/2010 R2 (La Sagra)
We present recent observations of main-belt comet P/2010 R2 (La Sagra)
obtained using the Gemini North telescope on five nights in late 2011 and early
2013 during portions of the object's orbit when dust emission was expected to
be minimal or absent. We find that P/La Sagra continues to exhibit a faint dust
trail aligned with its orbit plane as late as 2011 December 31, while no
activity is observed by the time of our next observations on 2013 March 3,
shortly before aphelion. Using only photometry measured when the comet was
observed to be inactive, we find best-fit IAU phase function parameters of
H_R=18.4+/-0.2 mag and G=0.17+/-0.10, corresponding to an effective nucleus
radius of r_N=0.55+/-0.05 km (assuming p_R=0.05). We revisit photometry
obtained when P/La Sagra was observed to be active in 2010 using our revised
determination of the object's nucleus size, finding a peak dust-to-nucleus mass
ratio of M_d/M_N = (5.8+/-1.6)x10^(-4), corresponding to an estimated total
peak dust mass of M_d = (5.3+/-1.5)x10^8 kg. We also compute the inferred peak
total active surface area and active surface fraction for P/La Sagra, finding
A_act ~ 5x10^4 m^2 and f_act ~ 0.01, respectively. Finally, we discuss P/La
Sagra's upcoming perihelion passage, particularly focusing on the available
opportunities to conduct follow-up observations in order to search for
recurrent activity and, if recurrent activity is present, to search for changes
in P/La Sagra's activity strength on successive orbit passages that should
provide insights into the evolution of MBC activity over time.Comment: 20 pages, 8 figures; accepted for publication in Icaru
Bulk Entanglement Spectrum Reveals Quantum Criticality within a Topological State
A quantum phase transition is usually achieved by tuning physical parameters
in a Hamiltonian at zero temperature. Here, we demonstrate that the ground
state of a topological phase itself encodes critical properties of its
transition to a trivial phase. To extract this information, we introduce a
partition of the system into two subsystems both of which extend throughout the
bulk in all directions. The resulting bulk entanglement spectrum has a
low-lying part that resembles the excitation spectrum of a bulk Hamiltonian,
which allows us to probe a topological phase transition from a single
wavefunction by tuning either the geometry of the partition or the entanglement
temperature. As an example, this remarkable correspondence between topological
phase transition and entanglement criticality is rigorously established for
integer quantum Hall states.Comment: 5 pages, 2 figures, 3 pages of Supplementary Materia
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