Searching for anomalous microwave emission in nearby galaxies. K-band observations with the Sardinia Radio Telescope
Journal
Date Issued
2022
Author(s)
•
•
•
•
Galliano, F.
•
•
Jones, A. P.
•
Madden, S. C.
•
•
•
Xilouris, E. M.
•
Ysard, N.
Abstract
Aims: We observed four nearby spiral galaxies (NGC 3627, NGC 4254, NGC 4736, and NGC 5055) in the K band with the 64-m Sardinia Radio Telescope, with the aim of detecting anomalous microwave emission (AME), a radiation component presumably due to spinning dust grains, which has been observed thus far in the Milky Way and only in a handful of other galaxies (most notably, M 31).
Methods: We mapped the galaxies at 18.6 and 24.6 GHz and studied their global photometry together with other radio-continuum data from the literature in order to find AME as emission in excess of the synchrotron and thermal components.
Results: We only found upper limits for AME. These nondetections, and other upper limits in the literature, are nevertheless consistent with the average AME emissivity from a few detections: it is ϵ30 GHzAME = 2.4 ± 0.4 × 10−2 MJy sr−1 (M⊙ pc−2)−1 in units of dust surface density (equivalently, 1.4 ± 0.2 × 10−18 Jy sr−1 (H cm−2)−1 in units of H column density). We finally suggest searching for AME in quiescent spirals with relatively low radio luminosity, such as M 31.
Aims: We observed four nearby spiral galaxies (NGC 3627, NGC 4254, NGC 4736, and NGC 5055) in the K band with the 64-m Sardinia Radio Telescope, with the aim of detecting anomalous microwave emission (AME), a radiation component presumably due to spinning dust grains, which has been observed thus far in the Milky Way and only in a handful of other galaxies (most notably, M 31).
Methods: We mapped the galaxies at 18.6 and 24.6 GHz and studied their global photometry together with other radio-continuum data from the literature in order to find AME as emission in excess of the synchrotron and thermal components.
Results: We only found upper limits for AME. These nondetections, and other upper limits in the literature, are nevertheless consistent with the average AME emissivity from a few detections: it is ϵ30 GHzAME = 2.4 ± 0.4 × 10−2 MJy sr−1 (M⊙ pc−2)−1 in units of dust surface density (equivalently, 1.4 ± 0.2 × 10−18 Jy sr−1 (H cm−2)−1 in units of H column density). We finally suggest searching for AME in quiescent spirals with relatively low radio luminosity, such as M 31.
Volume
658
Start page
L8
Issn Identifier
0004-6361
Ads BibCode
2022A&A...658L...8B
Rights
open.access
File(s)![Thumbnail Image]()
Loading...
Name
bianchi2022.pdf
Description
Pdf editoriale
Size
4.55 MB
Format
Adobe PDF
Checksum (MD5)
0d3e61c8aa01612a400b1a876833a6ab