Recent observations from the Atacama Large Millimeter/submillimeter Array (ALMA) have provided groundbreaking insights into the magnetic fields and galactic winds of the merging galaxy pair Arp 220, located approximately 250 million light-years from Earth. Researchers discovered that a magnetic superhighway funnels material between the cores of these galaxies, with powerful winds facilitating the movement of material into the circumgalactic medium.
The study, led by Enrique Lopez-Rodriguez from the University of South Carolina, emphasizes the significant impact of a galaxy’s magnetic fields on light due to the presence of elongated dust grains in interstellar space. These grains align with magnetic fields, resulting in the creation of polarized light that astronomers can use to map magnetic fields. This technique enabled the team to visualize the magnetic structures within Arp 220.
Mapping Magnetic Fields
Using ALMA, the researchers conducted a detailed 3D mapping of the magnetic fields and galactic winds in Arp 220. This effort revealed previously unseen details about the dusty cores and molecular outflows of the galaxies. Notably, the study reported the first detection of a polarized CO(3–2) molecular line emission, which traced the galactic outflow in the external galaxy and indicated that the outflowing gas carries a well-ordered magnetic field.
Galactic Dynamics and Star Formation
The findings indicate that Arp 220’s western nucleus, known as Arp 220 W, features a nearly vertical magnetic field aligned with a bipolar molecular outflow moving at approximately 500 km/second. This outflow is significant as it propels a magnetic superhighway out of the galaxy, suggesting that magnetic fields are a driving force behind gas-removing winds that inhibit star formation.
Significance of the Findings
The research highlights that the magnetic fields in Arp 220 are hundreds to thousands of times stronger than those found in the Milky Way’s disk. The presence of a highly-polarized bridge connecting the two galactic cores may facilitate the funneling of material and magnetic flux between them. The authors conclude that these findings suggest that strong magnetic fields may be common in extreme starbursts, playing a crucial role in regulating star formation and the transport of materials across cosmic time.
The results of this study are published in The Astrophysical Journal Letters, providing a benchmark for understanding the feedback processes in high-redshift systems. Future ALMA observations could further explore the presence of similar magnetic fields in ancient galaxies, potentially confirming the role of magnetic fields in galactic evolution.
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