- S. Raghunathan, et al., — First Constraints on the Epoch of Reionization Using the non-Gaussianity
of the Kinematic Sunyaev-Zel{'}dovich Effect from the South Pole Telescope
and {\it Herschel}-SPIRE Observations
- We report results from an analysis aimed at detecting the trispectrum of the
kinematic Sunyaev-Zel{'}dovich (kSZ) effect by combining data from the South
Pole Telescope (SPT) and {\it Herschel}-SPIRE experiments over a 100 ${\rm
deg}^{2}$ field. The SPT observations combine data from the previous and
current surveys, namely SPTpol and SPT-3G, to achieve depths of 4.5, 3, and 16
$\mu {\rm K-arcmin}$ in bands centered at 95, 150, and 220 GHz. For SPIRE, we
include data from the 600 and 857 GHz bands. We reconstruct the
velocity-induced large-scale correlation of the small-scale kSZ signal with a
quadratic estimator that uses two cosmic microwave background (CMB) temperature
maps, constructed by optimally combining data from all the frequency bands. We
reject the null hypothesis of a zero trispectrum at $10.3\sigma$ level.
However, the measured trispectrum contains contributions from both the kSZ and
other undesired components, such as CMB lensing and astrophysical foregrounds,
with kSZ being sub-dominant. We use the \textsc{Agora} simulations to estimate
the expected signal from CMB lensing and astrophysical foregrounds. After
accounting for the contributions from CMB lensing and foreground signals, we do
not detect an excess kSZ-only trispectrum and use this non-detection to set
constraints on reionization. By applying a prior based on observations of the
Gunn-Peterson trough, we obtain an upper limit on the duration of reionization
of $\Delta z_{\rm re, 50} < 4.5$ (95\% C.L). We find these constraints are
fairly robust to foregrounds assumptions. This trispectrum measurement is
independent of, but consistent with, {\it Planck}'s optical depth measurement.
This result is the first constraint on the epoch of reionization using the
non-Gaussian nature of the kSZ signal.
- Shunsuke Adachi, et al., — Exploration of the polarization angle variability of the Crab Nebula
with POLARBEAR and its application to the search for axion-like particles
- The Crab Nebula, also known as Tau A, is a polarized astronomical source at
millimeter wavelengths. It has been used as a stable light source for
polarization angle calibration in millimeter-wave astronomy. However, it is
known that its intensity and polarization vary as a function of time at a
variety of wavelengths. Thus, it is of interest to verify the stability of the
millimeter-wave polarization. If detected, polarization variability may be used
to better understand the dynamics of Tau A, and for understanding the validity
of Tau~A as a calibrator. One intriguing application of such observation is to
use it for the search of axion-light particles (ALPs). Ultralight ALPs couple
to photons through a Chern-Simons term, and induce a temporal oscillation in
the polarization angle of linearly polarized sources. After assessing a number
of systematic errors and testing for internal consistency, we evaluate the
variability of the polarization angle of the Crab Nebula using 2015 and 2016
observations with the 150 GHz POLARBEAR instrument. We place a median 95% upper
bound of polarization oscillation amplitude $A < 0.065^\circ$ over the
oscillation frequencies from $0.75~\mathrm{year}^{-1}$ to
$0.66~\mathrm{hour}^{-1}$. Assuming that no sources other than ALP are causing
Tau A's polarization angle variation, that the ALP constitutes all the dark
matter, and that the ALP field is a stochastic Gaussian field, this bound
translates into a median 95% upper bound of ALP-photon coupling
$g_{a\gamma\gamma} < 2.16\times10^{-12}\,\mathrm{GeV}^{-1}\times(m_a/10^{-21}
\mathrm{eV})$ in the mass range from $9.9\times10^{-23} \mathrm{eV}$ to
$7.7\times10^{-19} \mathrm{eV}$. This demonstrates that this type of analysis
using bright polarized sources is as competitive as those using the
polarization of cosmic microwave background in constraining ALPs.
- C. Tandoi, et al., — Flaring Stars in a Non-targeted mm-wave Survey with SPT-3G
- We present a flare star catalog from four years of non-targeted
millimeter-wave survey data from the South Pole Telescope (SPT). The data were
taken with the SPT-3G camera and cover a 1500-square-degree region of the sky
from $20^{h}40^{m}0^{s}$ to $3^{h}20^{m}0^{s}$ in right ascension and
$-42^{\circ}$ to $-70^{\circ}$ in declination. This region was observed on a
nearly daily cadence from 2019-2022 and chosen to avoid the plane of the
galaxy. A short-duration transient search of this survey yields 111 flaring
events from 66 stars, increasing the number of both flaring events and detected
flare stars by an order of magnitude from the previous SPT-3G data release. We
provide cross-matching to Gaia DR3, as well as matches to X-ray point sources
found in the second ROSAT all-sky survey. We have detected flaring stars across
the main sequence, from early-type A stars to M dwarfs, as well as a large
population of evolved stars. These stars are mostly nearby, spanning 10 to 1000
parsecs in distance. Most of the flare spectral indices are constant or gently
rising as a function of frequency at 95/150/220 GHz. The timescale of these
events can range from minutes to hours, and the peak $\nu L_{\nu}$ luminosities
range from $10^{27}$ to $10^{31}$ erg s$^{-1}$ in the SPT-3G frequency bands.