Magnetic fields and gas in the cluster influenced spiral galaxy NGC4254 - I. Radio and X-rays observations

TL;DR

This study uses radio, X-ray, and UV observations to analyze how environmental factors in the Virgo cluster influence the magnetic fields, gas, and star formation in the spiral galaxy NGC4254, revealing asymmetries and signs of recent interactions.

Contribution

It provides a detailed multi-wavelength analysis of NGC4254, highlighting the effects of cluster environment on its magnetic fields, gas distribution, and star formation, with new insights into tidal interactions and magnetic field behavior.

Findings

Asymmetric radio intensity distribution with larger extension to the north.

Detection of hot X-ray gas tracing star-forming regions.

Higher star formation rate compared to similar spirals.

Abstract

Radio observations can show how cluster galaxies are affected by various environmental factors. We made three frequency radio-polarimetric VLA observations and performed sensitive XMM-Newton observations in X-rays and UV light of NGC4254. The distribution of total radio intensity at 8.46 4.86 GHz reveals a global asymmetry with a more diffuse and almost two times larger extension to the north than to the south. The radio polarized intensity is even more asymmetric, showing a strange bright ridge in the southern disk edge, displaced to the downstream side of the local density wave. Magnetic arms can be also seen in other disk portions, mostly avoiding nearby optical spiral arms. Spatially resolved emission of hot X-ray gas from the whole galactic disk, with its soft component closely tracing star-forming regions, is detected. The slope of the local radio nonthermal-infrared relation is <1, thus smaller than for the radio thermal-infrared one (>1). Using the radio thermal emission-based star formation rate (SFR) we find higher extinction in more Halpha luminous star-forming regions with a power-law slope of 0.83. The galaxy's estimated mean SFR of 0.026 M_sun/yr/kpc^2 is three times larger than in other spirals of similar Hubble type. NGC4254 seems to belong to the class of `young' Virgo cluster members, which recently experienced a gravitational encounter at the cluster's periphery, which perturbed its spiral arms by tidal forces and triggered a burst of star-formation which still maintains strong radio and infrared emissions. Tidal forces could also sheared the magnetic field in the southern disk portion and led to the observed polarized ridge, though, magnetic field compression by weak ram pressure forces of the cluster gas cannot be excluded.