X-Ray Emission from the Hot Interstellar Medium and Southwest Radio Lobe of the Nearby Radio Galaxy Centaurus A

By R. Kraft, S. Vázquez, W. Forman, Christine Jones, S. Murray, M. Hardcastle, D. Worrall, E. Churazov. 2003

141 citations recorded by the source corpus.

We present results from two Chandra/ACIS-I observations and one XMM-Newton observation of X-ray emission from the interstellar medium (ISM) and the inner radio lobes of the nearby radio galaxy Centaurus A. The ISM has an average radial surface brightness profile that is well described by a β-model profile with index β = 0.40 ± 0.04 and a temperature of kBTISM ~ 0.29 keV beyond 2 kpc from the nucleus. We find that diffuse X-ray emission is coincident with the outer half of the southwest radio lobe, and a bright X-ray enhancement is detected along the edge of the lobe. On the basis of energetic and lifetime arguments, we reject a nonthermal explanation for this emission. We model this emission as a thin, hot shell or cap of X-ray-emitting plasma surrounding the radio lobe that was created by the supersonic inflation of the lobe. This plasma shell is both hotter than (kBTSH ~ 2.9 keV) and greatly overpressurized relative to the ambient ISM, indicating supersonic expansion. We estimate that the lobe is expanding into the ISM at approximately Mach 8.5, or 2400 km s-1. We are not directly observing the bow shock, but rather the cooler, denser material that is accumulating ahead of the contact discontinuity. The thermal energy in the shell is a significant fraction of the thermal energy of the hot ISM, demonstrating the possibility that the hot ISM of early galaxies can be reenergized by outflows from nuclear activity. Interestingly, no similarly bright X-ray emission is detected in or along the edge of the northeast lobe, implying that there are differences in the dynamics and evolution of the kiloparsec-scale radio components.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/53f586b4b607aef0313a362fded299dcc77e634d

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Citations in the corpus

Chandra and XMM-Newton Observations of a Sample of Low-Redshift FR I and FR II Radio Galaxy Nuclei (2005, background): “…of this problem is that the recent merger that has occurred in Cen Amay have provided additional material to accrete onto the supermassive black hole, triggering heightened nuclear activity and a new phase of radio activity, causing the supersonic reinflation of the lobes (Kraft et al. 2003).”
X-Ray Thermal Coronae of Galaxies in Hot Clusters: Ubiquity of Embedded Mini-Cooling Cores (2006, background): “Galaxy coronae with temperature of< 0.4 keV are indeed reported in poor environments (e.g.,∼ 0.25 keV gas in NGC 4697, Sarazin et al. 2001;∼ 0.3 keV gas in Centaurus A, Kraft et al. 2003), but the X-ray gas luminosities of these galaxies are all low.”
Relativistic jet feedback in high-redshift galaxies – I. Dynamics (2016, background): “Observational evidence of such shocked multiphase ISM have been obtained from extended X-ray emission from radio-loud galaxies (Kraft et al. 2003; Croston, Kraft & Hardcastle 2007; Mingo et al. 2011; Wang et al. 2012).”
Mechanical feedback from active galactic nuclei in galaxies, groups and clusters (2012, background): “A rapidly inflating lobe can drive shocks into the gas, producing edges in x-ray surface brightness that have been observed in a number of objects (e.g. Jones et al 2002, Smith et al 2002, Kraft et al 2003, McNamara et al 2005, Machacek et al 2006).”
Heating Hot Atmospheres with Active Galactic Nuclei (2007, background): “With the notable exceptions of the Mach 8 shock in Centaurus A (Kraft et al. 2003), the Mach 4 shock in NGC 3801 (Croston et al. 2007), and perhas sur- rounding the overpressured quasar 3C186 (Siemiginowska et al. 2005) there is little evidence for strong shocks surrounding the radio-lobe cavities…”
An X-Ray Study of Magnetic Field Strengths and Particle Content in the Lobes of FR II Radio Sources (2005, background): “…unknown, but given the close match of the detected X-rays to the shape of the radio-emitting lobes, must be significantly greater than 1: application of standard jump conditions would give k = 4, while the observed shock around the southern lobe of Cen A (Kraft et al. 2003) corresponds to k ≈ 10.”
The Cluster-Scale AGN Outburst in Hydra A (2004, background): “…there is commonly a bright rim around the radio lobe cavities in X-ray clusters, this is composed of cool (low entropy) gas, close to local pressure equilibrium (e.g. Nulsen et al. 2002), so that most cavities are not strongly over pressured (Cen A is a noteworthy exception, Kraft et al. 2003).”
Radio galaxies and feedback from AGN jets (2020, background): “…of X-ray emission (‘cavities’) associated with the kpcscale lobes of many RLAGN (e.g., Bı̂rzan et al., 2004), and also found a small number of unambiguous shock features, demonstrating supersonic bulk motion of the lobes through the medium (e.g., Kraft et al., 2003; Croston et al., 2009, 2011).”
Reflections of Active Galactic Nucleus Outbursts in the Gaseous Atmosphere of M87 (2003, background): “Clear examples of such alignments include a wide variety of systems ranging from galaxies with very modest gaseous atmospheres, such as Cen A (Kraft et al. 2003) and M84 (Finoguenov & Jones 2001), to those with rich luminous clusters, including Hydra A (McNamara et al. 2000; David et al. 2001;…”
Radio and X-Ray Observations of the Jet in Centaurus A (2003, background): “Angles to the line of sight∼ 50◦ are also more plausible in interpretations of the large-scale radio and X-ray properties of the source (e.g., Kraft et al. 2003).”
A RELATIONSHIP BETWEEN AGN JET POWER AND RADIO POWER (2010, background): “On average, shock energy is a modest correction toPcav, factor of a few in clusters, but the incidence and variety of AGN driven shocks is broad (e.g.Kraft et al. 2003; Wise et al. 2007).”