Evidence of AGN feedback and sloshing in the X-ray luminous NGC 1550 galaxy group
Artikel i vetenskaplig tidskrift, 2020

We present results from Giant Metrewave Radio Telescope and Chandra observations of the NGC 1550 galaxy group. Although previously thought of as relaxed, we show evidence that gas sloshing and active galactic nucleus (AGN) heating have affected the structure of the system. The 610 and 235 MHz radio images show an asymmetric jet-lobe structure with a total size of similar to 33 kpc, with a sharp kink at the base of the more extended western jet, and bending of the shorter eastern jet as it enters the lobe. The 235-610 MHz spectral index map shows that both radio lobes have steep spectral indices (alpha(610)(235) >= -1.5), indicating the presence of an old electron population. The X-ray images reveal an asymmetric structure in the hot gas correlated with the radio structure, as well as potential cavities coincident with the radio lobes, with rims and arms of gas that may have been uplifted by the cavity expansion. The X-ray residual map reveals an arc-shaped structure to the east that resembles a sloshing cold front. Radio spectral analysis suggests a radiative age of about 33 Myr for the source, comparable to the sloshing time-scale and dynamical estimates of the age of the lobes. An estimate of the mechanical energy required to inflate the cavities suggests that the AGN of NGC 1550 is capable of balancing radiative losses from the intragroup medium (IGM) and preventing excessive cooling, providing that the AGN jets are efficiently coupled to the IGM gas. In conclusion, we find evidence of sloshing motions from both radio and X-ray structures, suggesting that NGC 1550 was perturbed by a minor merger or infalling galaxy about 33 Myr ago.


galaxy evolution


galaxies: groups: general


Konstantinos Kolokythas

North-West University

Ewan O'Sullivan

Harvard-Smithsonian Center for Astrophysics

Simona Giacintucci

Naval Research Laboratory

Diana M. Worrall

University of Bristol

Mark Birkinshaw

University of Bristol

Somak Raychaudhury

University of Birmingham

Inter-University Centre for Astronomy and Astrophysics

Presidency University

Cathy Horellou

Chalmers, Rymd-, geo- och miljövetenskap, Astronomi och plasmafysik, Extragalaktisk astrofysik

Huib Intema

Universiteit Leiden

Ilani Loubser

North-West University

Monthly Notices of the Royal Astronomical Society

0035-8711 (ISSN) 1365-2966 (eISSN)

Vol. 496 2 1471-1487


Astronomi, astrofysik och kosmologi

Atom- och molekylfysik och optik




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