Evolution of star clusters with initial bulk rotation via N-body
simulations
Published on 27 May 2025, 2:26 AM
Young star clusters can inherit bulk rotation from the molecular clouds from
which they have formed. This rotation can affect the long-term evolution of a
star cluster and its constituent stellar populations. In this study, we aim to
characterize the effects of different degrees of initial rotation on star
clusters with primordial binaries. The simulations are performed using
NBODY6++GPU. We find that initial rotation strongly affects the early evolution
of star clusters. Rapidly rotating clusters show angular momentum transport
from the inner parts to the outskirts, resulting in a core collapse. Angular
momentum transport is accompanied by a highly elongated bar-like structure
morphology. The effects of bulk rotation are reduced on the timescale of
two-body relaxation. Rotating and non-rotating clusters experience changes in
the direction of angular momentum near the dissolution and early evolution due
to the tidal field, respectively. We present synthetic observations of
simulated clusters for comparison with future observations in filters of Gaia,
CSST, and HST. This work shows the effects of bulk rotation on systems with
primordial binaries and could be used for the identification of rotation
signatures in observed open clusters.
Dynamical evolution of massless particles in star clusters with
NBODY6++GPU-MASSLESS: I. Free-floating MLPs
Published on 12 December 2024, 5:25 AM
Context. Low-mass bodies, such as comets, asteroids, planetesimals, and
free-floating planets, are continuously injected into the intra-cluster
environment after expulsion from their host planetary systems. These can be
modeled as massless particles (MLPs, hereafter). The dynamics of large
populations of MLPs, however, has yet received little attention in literature.
Aims. We investigate the dynamical evolution of MLP populations in star
clusters, and characterize their kinematics and ejection rates. Methods. We
present NBODY6++GPU-MASSLESS, a modified version of the N-body simulation code
NBODY6++GPU, that allows fast integration of star clusters that contain large
numbers of massless particles (MLPs). NBODY6++GPU-MASSLESS contains routines
specifically directed at the dynamical evolution of low-mass bodies, such as
planets. Results. Unlike stars, MLPs do not participate in the mass segregation
process. Instead, MLPs mostly follow the gravitational potential of the star
cluster, which gradually decreases over time due to stellar ejections and
stellar evolution. The dynamical evolution of MLPs is primarily affected by the
evolution of the core of the star cluster. This is most apparent in the outer
regions for clusters with higher initial densities. High escape rates of MLPs
are observed before the core-collapse, after which escape rates remain stable.
Denser star clusters undergo a more intense core collapse, but this does not
impact the dynamical evolution of MLPs. The speeds of escaping stars are
similar to those of escaping MLPs, when disregarding the high-velocity
ejections of neutron stars during the first 50 Myr.
The 3D morphology of open clusters in the solar neighborhood III:
Fractal dimension
Published on 12 December 2024, 3:00 AM
We analyze the fractal dimension of open clusters using 3D spatial data from
Gaia DR3 for 93 open clusters from Pang et al. (2024) and 127 open clusters
from Hunt&Reffert (2024) within 500 pc. The box-counting method is adopted to
calculate the fractal dimension of each cluster in three regions: the
all-member region, $r \leq r_t$ (inside the tidal radius), and $r>r_t$
(outside the tidal radius). In both the Pang and Hunt catalogs, the fractal
dimensions are smaller for the regions $r>r_t$ than those for $r \leq r_t$,
indicating that the stellar distribution is more clumpy in the cluster
outskirts. We classify cluster morphology based on the fractal dimension via
the Gaussian Mixture Model. Our study shows that the fractal dimension can
efficiently classify clusters in the Pang catalog into two groups. The fractal
dimension of the clusters in the Pang catalog declines with age, which is
attributed to the development of tidal tails. This is consistent with the
expectations from the dynamical evolution of open clusters. We find strong
evidence that the fractal dimension increases with cluster mass, which implies
that higher-mass clusters are formed hierarchically from the mergers of
lower-mass filamentary-type stellar groups. The transition of the fractal
dimension for the spatial distribution of open clusters provides a useful tool
to trace the Galactic star forming structures, from the location of the Local
Bubble within the solar neighborhood to the spiral arms across the Galaxy.
FAST drift scan survey for HI intensity mapping: simulation on hunting
HI filament with pairwise stacking
Published on 06 November 2024, 11:29 PM
Filaments stand as pivotal structures within the cosmic web. However, direct
detection of the cold gas content of the filaments remains challenging due to
its inherent low brightness temperature. With the TNG hydrodynamical
simulations, we demonstrate the effectiveness of isolating faint filament HI
signal from the FAST HI intensity mapping (IM) survey through pairwise stacking
of galaxies, which yields an average HI filament signal amplitude of $\sim
0.29\ {\mu{\rm K}}$ at $z\simeq 0.1$. However, our simulations reveal a
non-negligible contribution from HI-rich galaxies within or near the filaments.
Particularly, the faint galaxies dominantly contribute to the extra filament HI
signal. Our simulation also shows that the measurement uncertainty is produced
by both thermal noise and background variation caused by brightness leakage
from surrounding random galaxies. Given a fixed total observation time, a
wide-field HI IM survey, which includes a large number of galaxy pairs, can
simultaneously reduce thermal noise to below the filament signal level and
minimize background variation to a negligible level. Through the end-to-end
simulation, this work demonstrates the critical role of the galaxy pairwise
stacking method in future filament HI detection, outlining a road map for
filament HI detection in the next-generation HI IM surveys.
QUIJOTE scientific results -- XVIII. New constraints on the polarization
of the Anomalous Microwave Emission in bright Galactic regions:
$ρ$\,Ophiuchi, Perseus and W43
Published on 05 September 2024, 7:06 PM
This work focuses on the study of the AME, an important emission mechanism
between 10 and 60 GHz whose polarization properties are not yet fully
understood, and is therefore a potential contaminant for future CMB
polarization observations. We use new QUIJOTE-MFI maps 11, 13, 17 and 19 GHz,
together with other public ancillary data including WMAP and Planck, to study
the polarization properties of the AME in three Galactic regions: rho-Ophiuchi,
Perseus and W43.
We have obtained the SEDs for those three regions over the frequency range
0.4-3000 GHz, both in intensity and polarization. The intensity SEDs are well
described by a combination of free-free emission, thermal dust, AME and CMB
anisotropies. In polarization, we extracted the flux densities using all
available data between 11 and 353 GHz. We implemented an improved
intensity-to-polarization leakage correction that has allowed for the first
time to derive reliable polarization constraints well below the 1% level from
Planck-LFI data. A frequency stacking of maps in the range 10-60 GHz has
allowed us to reduce the statistical noise and to push the upper limits on the
AME polarization level.
We have obtained upper limits on the AME polarization fraction of order<1%
(95% confidence level) for the three regions. In particular we get Pi_AME<1.1% (at 28.4 GHz), Pi_AME<1.1% (at 22.8 GHz) and Pi_AME<0.28% (at 33 GHz)
in rho-Ophiuchi, Perseus and W43 respectively. At the QUIJOTE 17 GHz frequency
band, we get Pi_AME<5.1% for rho-Ophiuchi, Pi_AME<3.5% for Perseus and
Pi_AME<0.85% for W43. Our final upper limits derived using the stacking
procedure are Pi_AME<0.58% for rho-Ophiuchi, Pi_AME<1.64% for Perseus and
Pi_AME<0.31% for W43. Altogether, these are the most stringent constraints to
date on the AME polarization fraction of these three star-forming regions.
Influence of planets on debris discs in star clusters -- II. The impact
of stellar density
Published on 02 September 2024, 3:22 PM
We present numerical simulations of planetary systems in star clusters with
different initial stellar densities, to investigate the impact of the density
on debris disc dynamics. We use LPS+ to combine N-body codes NBODY6++GPU and
REBOUND for simulations. We simulate debris discs with and without a
Jupiter-mass planet at 50 au, in star clusters with N = 1k - 64k stars. The
spatial range of the remaining planetary systems decreases with increasing N.
As cluster density increases, the planet's influence range first increases and
then decreases. For debris particles escaping from planetary systems, the
probability of their direct ejection from the star cluster decreases as their
initial semi-major axis (a0) or the cluster density increases. The eccentricity
and inclination of surviving particles increase as cluster density increases.
The presence of a planet leads to lower eccentricities and inclinations of
surviving particles. The radial density distribution of the remaining discs
decays exponentially in sparse clusters. We derive a general expression of the
gravitational encounter rate. Our results are unable to directly explain the
scarcity of debris discs in star clusters. Nevertheless, given that many
planetary systems have multiple planets, the mechanism of the planet-cluster
combined gravitational influence on the disc remains appealing as a potential
explanation.
FAST survey of H I and OH absorption towards extragalactic radio sources
Published on 29 June 2024, 12:14 AM
Neutral atomic hydrogen and molecular gas in the host galaxies of radio
active galactic nuclei (AGN) can be traced using H I 21-cm and OH-1667 MHz
absorption lines to understand the fueling and feedback processes. We present
the results of an H I and OH absorption survey with the Five-hundred-meter
Aperture Spherical radio Telescope (FAST) towards 40 radio sources of
low-intermediate radio luminosity ($\sim$10$^{23}$-10$^{26}$ W Hz$^{-1}$ at 1.4
GHz), red mid-infrared color (W2[4.6 $\mu$m]$-$W3[12 $\mu$m] $>$ 2.5 mag) and
redshift up to 0.35. From 13 sources with good data at H I observing
frequencies, we report the detection of H I absorption towards 8 sources, 5 of
which are new detections including 4 in the redshift range 0.25 to 0.35. Our
detection rates are consistent with our previous results with dependence on the
star-formation history of the host galaxy reflected in the mid-infrared
\textit{WISE} W2$-$W3 colors and the compactness of the radio source. We find
no significant dependence of detection rates on radio luminosity or redshift.
We also find that H I column densities are anti-correlated with the
low-frequency spectral indices ($\alpha_{\rm 150 MHz}^{\rm 1.4 GHz}$,
$S_{\nu}\propto \nu^{-\alpha}$). We do not have any detection from 23 sources
with good data at OH observing frequencies. However, by stacking the spectra we
estimate the 3$\sigma$ upper limit of OH column density to be
2.27$\times$10$^{14}$$T_{\rm ex}$/10 K $\times$1/$f_{\rm c}$ cm$^{-2}$. By
stacking the OH spectra for 7 associated H I absorbers, we get a 3$\sigma$
upper limit of 3.47$\times$10$^{14}$ $T_{\rm ex}$/10 K $\times$1/$f_{\rm c}$
cm$^{-2}$ on OH column density and 1.78$\times$10$^{-7}$ on [OH]/[H I] ratio.
The Present-Day Mass Function of Star Clusters in the Solar Neighborhood
Published on 14 March 2024, 2:00 AM
This work analyses the present-day mass function (PDMF) of 93~star clusters
utilizing Gaia DR3 data, with membership determined by the StarGo machine
learning algorithm. The impact of unresolved binary systems on mass estimation
is rigorously assessed, adopting three mass ratio profiles for correction. The
PDMF is characterized by the power-law index, $\alpha$, derived through a
robust maximum likelihood method that avoids biases associated with data
binning. The value of $\alpha$ for stars between the completeness limited mass
of Gaia with a mean 0.3 $M_\odot$ for our cluster samples and 2 $M_\odot$,
exhibits stability for clusters younger than 200 Myr, decreasing for older
clusters, particularly when considering stars within the half-mass radius. The
PDMF of these star clusters is consistent with a dynamically evolved Kroupa IMF
via the loss of low-mass stars. Cluster morphology shows a correlation with
$\alpha$, as $\alpha$ values exhibit a decreasing trend from filamentary to
tidal-tail clusters, mirroring the sequence of increasing cluster age. The
dependence of $\alpha$ on total cluster mass is weak, with a subtle increase
for higher-mass clusters, especially outside the half-mass radius. We do not
observe a correlation between $\alpha$ and the mean metallicity of the
clusters. Younger clusters have lower metallicity compared to their older
counterparts, which indicates that the older clusters might have migrated to
the solar neighbourhood from the inner disk. A comparison with numerical models
incorporating a black hole population suggests the need for observations of
distant, older, massive open clusters to determine whether or not they contain
black holes.
Analysis of Kozai Cycles in Equal-Mass Hierarchical Triple Supermassive
Black Hole Mergers in the Presence of a Stellar Cluster
Published on 28 December 2023, 8:15 PM
Supermassive black holes (SMBHs) play an important role in galaxy evolution.
Binary and triple SMBHs can form after galaxy mergers. A third SMBH may
accelerate the SMBH merging process, possibly through the Kozai mechanism. We
use N -body simulations to analyze oscillations in the orbital elements of
hierarchical triple SMBHs with surrounding star clusters in galaxy centers. We
find that SMBH triples spend only a small fraction of time in the hierarchical
merger phase (i.e., a binary SMBH with a distant third SMBH perturber). Most of
the time, the enclosed stellar mass within the orbits of the innermost or the
outermost SMBH is comparable to the SMBH masses, indicating that the influence
of the surrounding stellar population cannot be ignored. We search for
Eccentric Kozai-Lidov (EKL) oscillations for which (i) the eccentricity of the
inner binary and inclination are both oscillate and are anti-phase or in-phase
and (ii) the oscillation period is consistent with EKL timescale. We find that
EKL oscillations are short-lived and rare: the triple SMBH spends around 3% of
its time in this phase over the ensemble of simulations, reaching around 8% in
the best-case scenario. This suggests that the role of the EKL mechanism in
accelerating the SMBH merger process may have been overestimated in previous
studies. We follow-up with three-body simulations, using initial conditions
extracted from the simulation, and the result can to some extent repeat the
observed EKL-like oscillations. This comparison provides clues about why those
EKL oscillations with perturbing stars are short-lived.
Cross-correlation of cosmic voids with thermal Sunyaev-Zel'dovich data
Published on 02 November 2023, 4:16 AM
We provide a measurement of the deficit in the Sunyaev-Zel'dovich Compton-$y$
signal towards cosmic voids, by stacking a catalogue of 97,090 voids
constructed with BOSS-DR12 data, on the $y$ maps built on data from the Atacama
Cosmology Telescope (ACT) DR4 and the Planck satellite. We detect the void
signal with a significance of $7.3\,\sigma$ with ACT and $9.7\,\sigma$ with
Planck, obtaining agreements in the associated void radial $y$ profiles
extracted from both maps. The inner-void profile (for angular separations
within the void angular radius) is reconstructed with significances of
$4.7\sigma$ and $6.1\sigma$ with ACT and Planck, respectively; we model such
profile using a simple model that assumes uniform gas (under)density and
temperature, which enables us to place constraints on the product
$(-\delta_{\rm v}T_{\rm e})$ of the void density contrast (negative) and the
electron temperature. The best-fit values from the two data sets are
$(-\delta_{\rm v}T_{\rm e})=(6.5\pm 2.3)\times 10^{5}\,\text{K}$ for ACT and
$(8.6 \pm 2.1)\times 10^{5}\,\text{K}$ for Planck ($68\%$ C.L.), which are in
good agreement under uncertainty. The data allow us to place lower limits on
the expected void electron temperature at $2.7\times10^5\,\text{K}$ with ACT
and $5.1\times10^5\,\text{K}$ with Planck ($95\%$ C.L.); these results can
transform into upper limits for the ratio between the void electron density and
the cosmic mean as $n^{\rm v}_{\rm e}/\bar{n}_{\rm e}\leqslant 0.73$ and $0.49$
($95\%$ C.L.), respectively. Our findings prove the feasibility of using tSZ
observations to constrain the gas properties inside cosmic voids, and confirm
that voids are under-pressured regions compared to their surroundings.
Cross-correlation between the thermal Sunyaev-Zeldovich effect and the
Integrated Sachs-Wolfe effect
Published on 28 October 2023, 4:45 AM
We present a joint cosmological analysis of the power spectra measurement of
the Planck Compton parameter and the integrated Sachs-Wolfe (ISW) maps. We
detect the statistical correlation between the Planck Thermal Sunyaev-Zeldovich
(tSZ) map and ISW data with a significance of a $3.6\sigma$ confidence
level~(CL), with the autocorrelation of the Planck tSZ data being measured at a
$25 \sigma$ CL. The joint auto- and cross-power spectra constrain the matter
density to be $\Omega_{\rm m}= 0.317^{+0.040}_{-0.031}$, the Hubble constant
$H_{0}=66.5^{+2.0}_{-1.9}\,{\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$ and the rms
matter density fluctuations to be $\sigma_{8}=0.730^{+0.040}_{-0.037}$ at the
68% CL. The derived large-scale structure $S_{8}$ parameter is $S_8 \equiv
\sigma_{8}(\Omega_{\rm m}/0.3)^{0.5} = 0.755\pm{0.060} $. If using only the
diagonal blocks of covariance matrices, the Hubble constant becomes
$H_{0}=69.7^{+2.0}_{-1.5}\,{\rm km}\,{\rm s}^{-1}\,{\rm Mpc}^{-1}$. In
addition, we obtain the constraint of the product of the gas bias, gas
temperature, and density as $b_{\rm gas} \left(T_{\rm e}/(0.1\,{\rm keV})
\right ) \left(\bar{n}_{\rm e}/1\,{\rm m}^{-3} \right) =
3.09^{+0.320}_{-0.380}$. We find that this constraint leads to an estimate on
the electron temperature today as $T_{\rm e}=(2.40^{+0.250}_{-0.300}) \times
10^{6} \,{\rm K}$, consistent with the expected temperature of the warm-hot
intergalactic medium. Our studies show that the ISW-tSZ cross-correlation is
capable of probing the properties of the large-scale diffuse gas.
The dynamical evolution of protoplanetary disks and planets in dense
star clusters
Published on 13 September 2023, 5:03 PM
Most stars are born in dense stellar environments where the formation and
early evolution of planetary systems may be significantly perturbed by
encounters with neighbouring stars. To investigate on the fate of circumstellar
gas disks and planets around young stars dense stellar environments, we
numerically evolve star-disk-planet systems. We use the $N$-body codes
NBODY6++GPU and SnIPES for the dynamical evolution of the stellar population,
and the SPH-based code GaSPH for the dynamical evolution of protoplanetary
disks. The secular evolution of a planetary system in a cluster differs from
that of a field star. Most stellar encounters are tidal, adiabatic and
nearly-parabolic. The parameters that characterize the impact of an encounter
include the orientation of the protoplanetary disk and planet relative to the
orbit of the encountering star, and the orbital phase and the semi-major axis
of the planet. We investigate this dependence for close encounters ($r_p/a\leq
100$, where $r_p$ is the periastron distance of the encountering star and $a$
is the semi-major axis of the planet). We also investigate distant perturbers
($r_p/a\gg 100$), which have a moderate effect on the dynamical evolution of
the planet and the protoplanetary disk. We find that the evolution of
protoplanetary disks in star clusters differs significantly from that of
isolated systems. When interpreting the outcome of the planet formation
process, it is thus important to consider their birth environments.
QUIJOTE scientific results -- XIII. Intensity and polarization study of
supernova remnants in the QUIJOTE-MFI wide survey: CTB 80, Cygnus Loop, HB
21, CTA 1, Tycho and HB 9
Published on 28 July 2023, 8:19 PM
We use the new QUIJOTE-MFI wide survey (11, 13, 17 and 19 GHz) to produce
spectral energy distributions (SEDs), on an angular scale of 1 deg, of the
supernova remnants (SNRs) CTB 80, Cygnus Loop, HB 21, CTA 1, Tycho and HB 9. We
provide new measurements of the polarized synchrotron radiation in the
microwave range. For each SNR, the intensity and polarization SEDs are obtained
and modelled by combining QUIJOTE-MFI maps with ancillary data. In intensity,
we confirm the curved power law spectra of CTB 80 and HB 21 with a break
frequency $\nu_{\rm b}$ at 2.0$^{+1.2}_{-0.5}$ GHz and 5.0$^{+1.2}_{-1.0}$ GHz
respectively; and spectral indices respectively below and above the spectral
break of $-0.34\pm0.04$ and $-0.86\pm0.5$ for CTB 80, and $-0.24\pm0.07$ and
$-0.60\pm0.05$ for HB 21. In addition, we provide upper limits on the Anomalous
Microwave Emission (AME), suggesting that the AME contribution is negligible
towards these remnants. From a simultaneous intensity and polarization fit, we
recover synchrotron spectral indices as flat as $-0.24$, and the whole sample
has a mean and scatter of $-0.44\pm0.12$. The polarization fractions have a
mean and scatter of $6.1\pm1.9$\%. When combining our results with the
measurements from other QUIJOTE studies of SNRs, we find that radio spectral
indices are flatter for mature SNRs, and particularly flatter for CTB 80
($-0.24^{+0.07}_{-0.06}$) and HB 21 ($-0.34^{+0.04}_{-0.03}$). In addition, the
evolution of the spectral indices against the SNRs age is modelled with a
power-law function, providing an exponent $-0.07\pm0.03$ and amplitude
$-0.49\pm0.02$ (normalised at 10 kyr), which are conservative with respect to
previous studies of our Galaxy and the Large Magellanic Cloud.
Binary Star Evolution in Different Environments: Filamentary, Fractal,
Halo and Tidal-tail Clusters
Published on 14 July 2023, 2:00 AM
Using membership of 85 open clusters from previous studies (Pang et al.
2021a,b, 2022b; Li et al. 2021) based on Gaia DR3 data, we identify binary
candidates in the color-magnitude diagram, for systems with mass ratio q>0.4.
The binary fraction is corrected for incompleteness at different distances due
to the Gaia angular resolution limit. We find a decreasing binary fraction with
increasing cluster age, with substantial scatter. For clusters with a total
mass>200$M_\odot$, the binary fraction is independent of cluster mass. The
binary fraction depends strongly on stellar density. Among four types of
cluster environments, the lowest-density filamentary and fractal stellar groups
have the highest mean binary fraction: 23.6% and 23.2%, respectively. The mean
binary fraction in tidal-tail clusters is 20.8%, and is lowest in the densest
halo-type clusters: 14.8%. We find clear evidence of early disruptions of
binary stars in the cluster sample. The radial binary fraction depends strongly
on the cluster-centric distance across all four types of environments, with the
smallest binary fraction within the half-mass radius $r_h$, and increasing
towards a few $r_h$. Only hints of mass segregation is found in the target
clusters. The observed amount of mass segregation is not significant to
generate a global effect inside the target clusters. We evaluate the bias of
unresolved binary systems (assuming a primary mass of 1$M_\odot$) in 1D
tangential velocity, which is 0.1-1$\,\rm km\,s^{-1}$. Further studies are
required to characterize the internal star cluster kinematics using Gaia proper
motions.
Influence of planets on debris disks in star clusters I: the 50 AU
Jupiter
Published on 02 June 2023, 1:51 PM
Although debris disks may be common in exoplanet systems, only a few systems
are known in which debris disks and planets coexist. Planets and the
surrounding stellar population can have a significant impact on debris disk
evolution. Here we study the dynamical evolution of debris structures around
stars embedded in star clusters, aiming to determine how the presence of a
planet affects the evolution of such structures. We combine NBODY6++GPU and
REBOUND to carry out N-body simulations of planetary systems in star clusters
(N=8000; Rh=0.78 pc) for a period of 100 Myr, in which 100 solar-type stars are
assigned 200 test particles. Simulations are carried out with and without a
Jupiter-mass planet at 50 au. We find that the planet destabilizes test
particles and speeds up their evolution. The planet expels most particles in
nearby and resonant orbits. Remaining test particles tend to retain small
inclinations when the planet is present, and fewer test particles obtain
retrograde orbits. Most escaping test particles with speeds smaller than the
star cluster's escape speed originate from cold regions of the planetary system
or from regions near the planet. We identify three regions within planetary
systems in star clusters: (i) the private region of the planet, where few
debris particles remain (40 - 60 au), (ii) the reach of the planet, in which
particles are affected by the planet (0 - 400 au), and (iii) the territory of
the planetary system, most particles outside which will eventually escape (0 -
700 au).
QUIJOTE Scientific Results -- XVII. Studying the Anomalous Microwave
Emission in the Andromeda Galaxy with QUIJOTE-MFI
Published on 15 May 2023, 7:17 PM
The Andromeda Galaxy (M31) is the Local Group galaxy that is most similar to
the Milky Way (MW). The similarities between the two galaxies make M31 useful
for studying integrated properties common to spiral galaxies. We use the data
from the recent QUIJOTE-MFI Wide Survey, together with new raster observations
focused on M31, to study its integrated emission. The addition of raster data
improves the sensitivity of QUIJOTE-MFI maps by almost a factor 3. Our main
interest is to confirm if anomalous microwave emission (AME) is present in M31,
as previous studies have suggested. To do so, we built the integrated spectral
energy distribution of M31 between 0.408 and 3000 GHz. We then performed a
component separation analysis taking into account synchrotron, free-free, AME
and thermal dust components. AME in M31 is modelled as a log-normal
distribution with maximum amplitude, $A_{\rm AME}$, equal to $1.03\pm0.32$ Jy.
It peaks at $\nu_{\rm AME}=17.2\pm3.2$ GHz with a width of $W_{\rm
AME}=0.58\pm0.16$. Both the Akaike and Bayesian Information Criteria find the
model without AME to be less than 1 % as probable as the one taking AME into
consideration. We find that the AME emissivity per 100 $\mu$m intensity in M31
is $\epsilon_{\rm AME}^{\rm 28.4\,GHz}=9.6\pm3.1$ $\mu$K/(MJy/sr), similar to
that computed for the MW. We also provide the first upper limits for the AME
polarization fraction in an extragalactic object. M31 remains the only galaxy
where an AME measurement has been made of its integrated spectrum.
QUIJOTE scientific results -- X. Spatial variations of Anomalous
Microwave Emission along the Galactic plane
Published on 11 May 2023, 8:33 PM
Anomalous Microwave Emission (AME) is an important emission component between
10 and 60 GHz that is not yet fully understood. It seems to be ubiquituous in
our Galaxy and is observed at a broad range of angular scales. Here we use the
new QUIJOTE-MFI wide survey data at 11, 13, 17 and 19 GHz to constrain the AME
in the Galactic plane ($|b|<10^\circ$) on degree scales. We built the spectral
energy distribution between 0.408 and 3000 GHz for each of the 5309 0.9$^\circ$
pixels in the Galactic plane, and fitted a parametric model by considering five
emission components: synchrotron, free-free, AME, thermal dust and CMB
anisotropies. We show that not including QUIJOTE-MFI data points leads to the
underestimation (up to 50 %) of the AME signal in favour of free-free emission.
The parameters describing these components are then intercompared, looking for
relations that help to understand AME physical processes. We find median values
for the AME width, $W_{\rm AME}$, and for its peak frequency, $\nu_{\rm AME}$,
respectively of $0.560^{+0.059}_{-0.050}$ and $20.7^{+2.0}_{-1.9}$ GHz,
slightly in tension with current theoretical models. We find spatial variations
throughout the Galactic plane for $\nu_{\rm AME}$, but only with reduced
statistical significance. We report correlations of AME parameters with certain
ISM properties, such as that between the AME emissivity (which shows variations
with the Galactic longitude) and the interstellar radiation field, and that
between the AME peak frequency and dust temperature. Finally, we discuss the
implications of our results on the possible molecules responsible for AME.
Exploring the mass and redshift dependence of the cluster pressure
profile with stacks on thermal SZ maps
Published on 13 February 2023, 7:15 PM
We provide novel constraints on the parameters defining the universal
pressure profile (UPP) within clusters of galaxies, and explore their
dependence on the cluster mass and redshift, from measurements of
Sunyaev-Zel'dovich Compton-$y$ profiles. We employ both the $\textit{Planck}$
2015 MILCA and the ACT-DR4 $y$ maps over the common $\sim 2,100\,\text{deg}^2$
footprint. We combine existing cluster catalogs based on KiDS, SDSS and DESI
observations, for a total of 23,820 clusters spanning the mass range
$10^{14.0}\,\text{M}_{\odot}
Star forming brightest cluster galaxies at $z\sim0.4$ in KiDS. Further
studies of cold gas and stellar properties
Published on 11 February 2023, 12:20 AM
Brightest cluster galaxies (BCGs) are among the most massive galaxies in the
Universe. Their star formation (SF) history and stellar mass assembly are
debated. Recent studies suggest the presence of an emerging population of
intermediate-$z$ star forming and gas-rich BCGs, where the molecular gas
reservoirs are impacted by strong environmental processing. We have selected
three among the most star-forming $z\sim0.4$ BCGs in the Kilo-Degree Survey
(KiDS), and observed them with the IRAM 30m telescope in the first three CO
transitions. We found double-horn CO(1$\rightarrow$0) and CO(3$\rightarrow$2)
emission for the KiDS 1433 BCG, yielding a large molecular gas reservoir with
$M_{H_2}=(5.9\pm1.2)\times10^{10}~M_\odot$ and a high gas-to-stellar mass ratio
$M_{H_2}/M_\star=(0.32^{+0.12}_{-0.10})$. We increase the limited sample of
distant BCGs with detections in multiple CO transitions. The double-horn
emission for the KiDS 1433 BCG implies a low gas concentration, while a
modeling of the spectra yields an extended molecular gas reservoir, with a
characteristic radius of $\sim$(5-7) kpc, which is reminiscent of a mature
extended-disk phase observed in some local BCGs. For the other two BCGs we are
able to set upper limits of $M_{H_2}/M_\star<0.07$ and $<0.23$, which are among
the lowest for distant BCGs. We then combined our observations with available
stellar, SF, and dust properties of the targeted BCGs, and compared them with
$\sim100$ distant cluster galaxies, including additional intermediate-$z$ BCGs,
with observations in CO from the literature. The molecular gas properties of
star forming BCGs are heterogeneous. On one side, gas-rich BCGs show extended
gas reservoirs, which sustain the significant SF activity, which is reminiscent
of recent gas infall. Conversely, the existence of similarly star forming, but
gas-poor, BCGs suggest that gas depletion precedes SF quenching.
QUIJOTE scientific results -- IX. Radio sources in the QUIJOTE-MFI wide
survey maps
Published on 13 January 2023, 12:17 AM
We present the catalogue of Q-U-I JOint TEnerife (QUIJOTE) Wide Survey radio
sources extracted from the maps of the Multi-Frequency Instrument compiled
between 2012 and 2018. The catalogue contains 786 sources observed in intensity
and polarization, and is divided into two separate sub-catalogues: one
containing 47 bright sources previously studied by the \emph{Planck}
collaboration and an extended catalogue of 739 sources either selected from the
\emph{Planck} Second Catalogue of Compact Sources or found through a blind
search carried out with a Mexican Hat 2 wavelet. A significant fraction of the
sources in our catalogue (38.7 per cent) are within the $|b| \leq 20^\circ$
region of the Galactic plane. We determine statistical properties for those
sources that are likely to be extragalactic. We find that these statistical
properties are compatible with currently available models, with a $\sim$1.8 Jy
completeness limit at 11 GHz. We provide the polarimetric properties of (38,
33, 31, 23) sources with P detected above the $99.99\%$ significance level at
(11, 13, 17, 19) GHz, respectively. Median polarization fractions are in the
$2.8$-$4.7$\% range in the 11-19 GHz frequency interval. We do not distinguish
between Galactic and extragalactic sources here. The results presented here are
consistent with those reported in the literature for flat- and steep-spectrum
radio sources.
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