The Cluster-central Compact Steep-spectrum Radio Galaxy 1321+045
Abstract
The radio galaxy 1321+045 is a rare example of a young, compact steep-spectrum source located in the center of a z = 0.263 galaxy cluster. Using a combination of Chandra, VLBA, VLA, MERLIN, and IRAM 30 m observations, we investigate the conditions that have triggered this outburst. We find that the previously identified 5 kpc scale radio lobes are probably no longer powered by the active galactic nucleus, which seems to have launched a new ∼20 pc jet on a different axis, likely within the last few hundred years. We estimate the enthalpy of the lobes to be ${8.48}_{-3.56}^{+6.04}\times {10}^{57}\,\mathrm{erg}$ , only sufficient to balance cooling in the surrounding 16 kpc for ∼9 Myr. The properties of the cluster's intracluster medium (ICM) are similar to those of rapidly cooling nearby clusters, with a low central entropy (8.6 ${}_{-1.4}^{+2.2}$ keV cm2 within 8 kpc), short central cooling time (390 ${}_{-150}^{+170}$ Myr), and tcool/tff and tcool/teddy ratios indicative of thermal instability out to ∼45 kpc. Despite previous detection of Hα emission from the brightest cluster galaxy, our IRAM 30 m observations do not detect CO emission in either the (1-0) or (3-2) transitions. We place 3σ limits on the molecular gas mass of Mmol ≤ 7.7 × 109 M⊙ and ≤5.6 × 109 M⊙ from the two lines respectively. We find indications of a recent minor cluster merger that has left a ∼200 kpc tail of stripped gas in the ICM, and probably induced sloshing motions.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- June 2021
- DOI:
- 10.3847/1538-4357/abf6c6
- arXiv:
- arXiv:2104.04548
- Bibcode:
- 2021ApJ...913..105O
- Keywords:
-
- Galaxy clusters;
- Radio galaxies;
- Active galactic nuclei;
- Intracluster medium;
- Brightest cluster galaxies;
- 584;
- 1343;
- 16;
- 858;
- 181;
- Astrophysics - Cosmology and Nongalactic Astrophysics;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 18 pages, 9 figures, 4 tables, accepted for publication in ApJ, v2 updates references and corrects minor typographical errors identified at the proof stage