arXiv subjects

C. Arce-Tord

Publications and source records attributed to C. Arce-Tord.

3 recordsLinked to original sources

arXiv2026

Challenges in probing turbulent and magnetic support in cores: the W43-MM1 protocluster case study

Estimating the level of non-thermal support in cores is both challenging and crucial for constraining the earliest stages of star formation. We quantify the kinetic and magnetic support operating within the cores of the high-mass protocluster W43-MM1, and test the assumptions behind the virial theorem used to interpret observations. We used ALMA 12m molecular line observations of DCN (3-2), 13CS (5-4), and CH3CN (5_3-4_3) to estimate kinetic support. The plane-of-sky magnetic field strength (B_POS) was derived from dust-polarization observations using the Davis-Chandrasekhar-Fermi method, obtained at the three-beam scale (~12500 au) and extrapolated to core scales (~2500 au) using the density-field strength relation. We derive kinetic support estimates for 45 cores (21 prestellar and 24 protostellar), of which 21 also have magnetic field estimates. Velocity dispersions range from 0.34 to 4.48 km/s, and B_POS values span 1.1-49.3 mG at core scales. Using the virial theorem, ~70% of cores appear stable against collapse when considering turbulence alone, and ~85% when combining both kinetic and magnetic support (alpha_vir,B > 1). These are unexpectedly high values, particularly for protostellar cores expected to be undergoing collapse. We conclude that contamination of linewidths by organized motions (1-3 km/s, consistent with previous observational studies), together with the omission of surface terms in the observational virial theorem, prevents accurate measurement of non-thermal support in cores. This highlights that simplified virial analyses can introduce significant biases when assessing physical support mechanisms within cores.

astro-ph.GA↗

arXiv2023

QUIJOTE Scientific Results -- XVII. Studying the Anomalous Microwave Emission in the Andromeda Galaxy with QUIJOTE-MFI

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 $ν_{\rm AME}=17.2\pm3.2$ 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 $μ$m intensity in M31 is $ε_{\rm AME}^{\rm 28.4\,GHz}=9.6\pm3.1$ $μ$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.

astro-ph.GA↗

arXiv2020

Outflows, cores and magnetic field orientations in W43-MM1 as seen by ALMA

It has been proposed that the magnetic field, pervasive in the ISM, plays an important role in the process of massive star formation. To better understand its impact at the pre and protostellar stages, high-angular resolution observations of polarized dust emission toward a large sample of massive dense cores are needed. To this end, we used the Atacama Large Millimeter Array in Band 6 (1.3 mm) in full polarization mode to map the polarized emission from dust grains at a physical scale of $\sim$2700 au in the massive protocluster W43-MM1. We used these data to measure the orientation of the magnetic field at the core scale. Then, we examined the relative orientations of the core-scale magnetic field, of the protostellar outflows determined from CO molecular line emission, and of the major axis of the dense cores determined from 2D Gaussian fit in the continuum emission. We found that the orientation of the dense cores is not random with respect to the magnetic field. Instead, the dense cores are compatible with being oriented 20-50$^°$ with respect to the magnetic field. The outflows could be oriented 50-70$^°$ with respect to the magnetic field, or randomly oriented with respect to the magnetic field, similar to current results in low-mass star-forming regions. In conclusion, the observed alignment of the position angle of the cores with respect to the magnetic field lines shows that the magnetic field is well coupled with the dense material; however, the 20-50$^°$ preferential orientation contradicts the predictions of the magnetically-controlled core-collapse models. The potential correlation of the outflow directions with respect to the magnetic field suggests that, in some cases, the magnetic field is strong enough to control the angular momentum distribution from the core scale down to the inner part of the circumstellar disks where outflows are triggered.

astro-ph.GA↗