Kavli Affiliate: Gregory J. Herczeg
| First 5 Authors: Antonio Garufi, Carlos Carrasco-Gonzalez, Enrique Macias, Leonardo Testi, Pietro Curone
| Summary:
The last decade has witnessed remarkable advances in the characterization of
the (sub-)millimeter emission from planet-forming disks. Instead, the study of
the (sub-)centimeter emission has made more limited progress, to the point that
only a few exceptional disk-bearing objects have been characterized in the
centimeter regime. This work takes a broad view of the centimeter emission from
a large sample with VLA observations that is selected from previous ALMA
surveys of more representative disks in brightness and extent. We report on the
detection and characterization of flux at centimeter wavelengths from 21
sources in the Taurus star-forming region. Complemented by literature and
archival data, the entire photometry from 0.85 mm to 6 cm is fitted by a
two-component model that determines the ubiquitous presence of free-free
emission entangled with the dust emission. The flux density of the free-free
emission is found to scale with the accretion rate but is independent of the
outer disk morphology depicted by ALMA. The dust emission at 2 cm is still
appreciable, and offers the possibility to extract an unprecedented large set
of dust spectral indices in the centimeter regime. A pronounced change between
the median millimeter indices (2.3) and centimeter indices (2.8) suggests that
a large portion of the disk emission is optically thick up to 3 mm. The
comparison of both indices and fluxes with the ALMA disk extent indicates that
this portion can be as large as 40 au, and suggests that the grain population
within this disk region that emits the observed centimeter emission is similar
in disks with different size and morphology. All these results await
confirmation and dedicated dust modeling once facilities like ngVLA or SKA-mid
are able to resolve the centimeter emission from planet-forming disks and
disentangle the various components.
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