The<i>XMM‐Newton</i>Examination of Energetics in the East Lobe of the Nearby Radio Galaxy Fornax A (NGC 1316)

Isobe, Naoki; Makishima, Kazuo; Tashiro, M.; Itoh, K.; Iyomoto, Naoko; Takahashi, Isao; Kaneda, Hidehiro

doi:10.1086/504253

Cited by 27 publications

(62 citation statements)

References 33 publications

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“…Correspondingly, the data points for such sources should deviate downward from the u e -D correlation in Figure 7. Actually, in the lobes of Fornax A which is reported to host a dormant nucleus (Iyomoto et al 1998;Kim & Fabbiano 2003), the values of u e , precisely determined through various X-ray observations (e.g., Isobe et al 2006;Tashiro et al 2009), are found to be lower than the trend of the other radio galaxies by one order of magnitude (see Figure 7).…”

Section: +019mentioning

confidence: 88%

“…Since the discovery of the IC X-ray emission from the lobes of Fornax A with ASCA (e.g., Kaneda et al 1995) and ROSAT (Feigelson et al 1995), tremendous progress was achieved by this method with Chandra (e.g., Isobe et al 2002;Croston et al 2005) and XMM-Newton (e.g., Isobe et al 2005Isobe et al , 2006Migliori et al 2007), on the energetics in the lobes of radio galaxies. A number of studies (e.g., Isobe et al 2002;Croston et al 2005) suggested an electron dominance of u e /u m = 1 -100 in the lobes.…”

Section: Introductionmentioning

confidence: 99%

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SUZAKUDIAGNOSTICS OF THE ENERGETICS IN THE LOBES OF THE GIANT RADIO GALAXY 3C 35

Isobe¹,

Seta²,

Gandhi³

et al. 2011

ApJ

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The Suzaku observation of a giant radio galaxy 3C 35 revealed faint extended X-ray emission, associated with its radio lobes and/or host galaxy. After careful subtraction of the X-ray and non-X-ray background and contaminating X-ray sources, the X-ray spectrum of the faint emission was reproduced by a sum of the power-law (PL) and soft thermal components. The soft component was attributed to the thermal plasma emission from the host galaxy. The photon index of the PL component, Γ = 1.35 +0.56 −0.86−0.10 where the first and second errors represent the statistical and systematic ones, was found to agree with the synchrotron radio index from the lobes, Γ R = 1.7. Thus, the PL component was attributed to the inverse Compton (IC) X-rays from the synchrotron electrons in the lobes. The X-ray flux density at 1 keV was derived as 13.6 ± 5.4 +4.0 −3.6 nJy with the photon index fixed at the radio value. The X-ray surface brightness from these lobes (∼ 0.2 nJy arcmin −2 ) is lowest among the lobes studied through the IC X-ray emission. In combination with the synchrotron radio flux density, 7.5 ± 0.2 Jy at 327.4 MHz, the electron energy density spatially averaged over the lobes was evaluated to be the lowest among those radio galaxies, as u e = (5.8±2.3 +1.9 −1.7 )×10 −14 ergs cm −3 over the electron Lorentz factor of 10 3 -10 5 . The magnetic energy density was calculated as u m = (3.1 +2.5 −0.14 µG. These results suggest that the energetics in the 3C 35 lobes are nearly consistent with equipartition between the electrons and magnetic fields.

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Section: +019mentioning

confidence: 88%

Section: Introductionmentioning

confidence: 99%

SUZAKUDIAGNOSTICS OF THE ENERGETICS IN THE LOBES OF THE GIANT RADIO GALAXY 3C 35

Isobe¹,

Seta²,

Gandhi³

et al. 2011

ApJ

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“…Figure 9 summarizes u e and u m in lobes of radio galaxies, determined through IC X-ray technique (Croston et al 2005;Isobe et al , 2005Isobe et al , 2006Tashiro et al 1998Tashiro et al , 2009). We confirmed that almost all the radio lobes are distributed between the lines of u e /u m = 1 and 100 (e.g., Isobe et al 2005;Croston et al 2005), over a wide range of u e and u m .…”

Section: Evolution Of Lobe Energeticsmentioning

confidence: 99%

“…This proportionality is thought to be justified by the fact that the observed expansion speed of lobes are distributed in a relatively narrow range of 0.01c-0.1c (e.g., Figure 10. Energy densities of electrons (left) and magnetic fields (right), u e and u m , respectively, in lobes (Croston et al 2005;Isobe et al , 2005Isobe et al , 2006Tashiro et al 1998Tashiro et al , 2009), plotted against the total size, D, of radio galaxies. The circle corresponds to the west lobe of 3C 326, for which the statistical and systematic errors in S X are taken into account.…”

Section: Evolution Of Lobe Energeticsmentioning

confidence: 99%

“…Motivated by the pioneering discoveries of lobe IC X-rays with ROSAT and ASCA from Fornax A (Feigelson et al 1995;Kaneda et al 1995;Tashiro et al 2001) and Centaurus B , several subsequent studies with Chandra (e.g., Croston et al 2005;Kataoka & Stawarz 2005) and XMM-Newton (e.g., Isobe et al 2005Isobe et al , 2006Migliori et al 2007) proved the usefulness of this technique. Moreover, such research has revealed an electron dominance of u e /u m = 1-10 typically in lobes of moderate radio galaxies (e.g., Croston et al 2005).…”

Section: Introductionmentioning

confidence: 99%

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SUZAKUOBSERVATION OF THE GIANT RADIO GALAXY 3C 326

Isobe

Tashiro

Gandhi

et al. 2009

ApJ

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A Suzaku observation of a giant radio galaxy, 3C 326, which has a physical size of about 2 Mpc, was conducted on 2008 January 19-21. In addition to several X-ray sources, diffuse emission was significantly detected and associated with its west lobe, but the east lobe was contaminated by an unidentified X-ray source WARP J1552.4+2007. After careful evaluation of the X-ray and non-X-ray background, the 0.4-7 keV X-ray spectrum of the west lobe is described by a power-law model modified with the Galactic absorption. The photon index and 1 keV flux density were derived as Γ = 1.82 +0.26 −0.24 ± 0.04 and S X = 19.4 +3.3 −3.2 ± 3.0 nJy, respectively, where the first and second errors represent the statistical and systematic ones. The diffuse X-rays were attributed to be inverse Compton (IC) radiation by the synchrotron radio electrons scattering off the cosmic microwave background photons. This radio galaxy is the largest among those with lobes detected through IC X-ray emission. A comparison of the radio to X-ray fluxes yields the energy densities of electron and magnetic field as u e = (2.3 ± 0.3 ± 0.3) × 10 −13 erg cmand u m = (1.2 +0.2 −0.1 ± 0.2) × 10 −14 erg cm −3 , respectively. The galaxy is suggested to host a low-luminosity nucleus with an absorption-corrected 2-10 keV luminosity of < 2 × 10 42 erg s −1 , together with a relatively weak radio core. The energetics in the west lobe of 3C 326 were compared with those of moderate radio galaxies with a size of ∼100 kpc. The west lobe of 3C 326 is confirmed to agree with the correlations for the moderate radio galaxies, u e ∝ D −2.2±0.4 and u m ∝ D −2.4±0.4 , where D is their total physical size. This implies that the lobes of 3C 326 are still being energized by the jet, despite the current weakness of the nuclear activity.

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Spectral ageing analysis and dynamical analysis of the double-double radio galaxy J1548–3216

Machalski¹,

Jamrozy²,

Konar³

2010

A&A

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Context. Determining ages of the outer and the inner lobes of so-called double-double radio galaxies (DDRGs) is crucial for understanding the active cycles of galactic nuclei, the phases of interruption of the jet flow, and physical conditions in the surrounding galactic and intergalactic medium governing the jets' propagation. A recognition and understanding of these conditions during the restarted jet activity is of special interest. Aims. We determine the ages and other physical characteristics of the outer and the inner lobes of the DDRG J1548−3216, as well as the properties of the surrounding environment during the original and the restarted phase of the jets' activity. Methods. Using the new low-frequency and high-frequency radio images of this galaxy, we determined the shape of the spectrum along its lobes and performed the classical spectral-ageing analysis. On the other hand, we applied the analytical model of the jet's dynamics, which allowed us to derive the physical conditions for the source's evolution during the original jet propagation through the unperturbed IGM, as well as those when the restarted new jet propagates inside the outer cocoon formed by the old jet material that passed through the jet terminal shock. Results. The dynamical age estimate of the outer and the inner lobes is 132 ± 28 Myr and ∼9 ± 4 Myr, respectively. The synchrotron age in the outer lobes systematically rises from ∼25 Myr in the vicinity of the lobes' edges to about 65-75 Myr in the centre of the old cocoon. These ages imply an average expansion speed along the jets' axis: (0.012 ± 0.003)c in the outer lobes and (0.058 ± 0.025)c in the inner lobes, but the latter speed would be ∼0.25 c when they were of age less than 1 Myr. We find that the jet power during the restarted activity is about ten-fold fainter than that of the original jet. Similar disproportion is found for the internal pressures and the magnetic field strengths in the old cocoon and those in the inner lobes. This disproportion can be effectively reduced by assuming the same equations of state for the emitting particles and the magnetic fields within the old and the new lobes. However, we think that our assumption of the non-relativistic equation of state for the old cocoon and the relativistic one for the new lobes is more justified.

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TheXMM‐NewtonExamination of Energetics in the East Lobe of the Nearby Radio Galaxy Fornax A (NGC 1316)

Cited by 27 publications

References 33 publications

SUZAKUDIAGNOSTICS OF THE ENERGETICS IN THE LOBES OF THE GIANT RADIO GALAXY 3C 35

SUZAKUDIAGNOSTICS OF THE ENERGETICS IN THE LOBES OF THE GIANT RADIO GALAXY 3C 35

SUZAKUOBSERVATION OF THE GIANT RADIO GALAXY 3C 326

Spectral ageing analysis and dynamical analysis of the double-double radio galaxy J1548–3216

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