Chandra X-Ray Imaging and Spectroscopy of the M87 Jet and Nucleus

By A. S. Wilson, Y. Yang. 2001

141 citations recorded by the source corpus.

We report X-ray imaging spectroscopy of the jet of M87 at subarcsecond resolution with the Chandra X-ray Observatory. The galaxy nucleus and all the knots seen at radio and optical wavelengths, as far from the nucleus as knot C, are detected in the X-ray observations. There is a strong trend for the ratio of X-ray-to-radio, or optical, flux to decline with increasing distance from the nucleus. At least three knots are displaced from their radio/optical counterparts, being tens of parsecs closer to the nucleus at X-ray than at radio or optical wavelengths. The X-ray spectra of the nucleus and knots are well described by power laws absorbed by cold gas, with only the unresolved nucleus exhibiting intrinsic absorption. In view of the similar spectra of the nucleus and jet knots, and the high X-ray flux of the knots closest to the nucleus, we suggest that the X-ray emission coincident with the nucleus may actually originate from the parsec- or subparsec-scale jet rather than the accretion disk. Arguments are given that the X-ray emission process is unlikely to be inverse Compton scattering. Instead, we favor synchrotron radiation. Plotted as νSν, the spectra of the knots generally peak in or just above the optical-near-infrared band. However, the overall spectra of at least three knots cannot be described by simple models in which the spectral index monotonically increases with frequency, as would result from synchrotron losses or a high-energy cut-off to the injected electron spectrum. Instead, these spectra must turn down just above the optical band and then flatten in the X-ray band. In the context of a synchrotron model, this result suggests that either the X-ray-emitting electrons/positrons in these knots represent a separate "population" from those that emit the radio and optical radiation or that the magnetic field is highly inhomogeneous. If the former interpretation is correct, our results provide further support for the notion that radio galaxies produce a hard [γ ≃ 2-2.5, N(E) ∝ E-γ] spectrum of high-energy [ ~ 107-108] electrons and possibly positrons.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/fed93c1a4767948c36f398d92ff8e8159a431496

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Citations in the corpus

Spine–sheath layer radiative interplay in subparsec‐scale jets and the TeV emission from M87 (2008, unknown): “Note that the slope [α = 1.3 ± 0.1; F (ν) ∝ ν−α] is intermediate between that reported in Marshall et al. (2002) (α = 1.47 ± 0.08, see also Donato, Sambruna & Gliozzi 2004) and that of Wilson & Yang (2002) (α = 1.17 ± 0.1).”
A Survey of Extended Radio Jets with Chandra and the Hubble Space Telescope (2004, background): “The steep X-ray spectrum suggests synchrotron emission from a separate population of particles (Wilson & Yang 2002), indicating jet inhomogeneities.”
The Structure and Dynamics of the Subparsec Jet in M87 Based on 50 VLBA Observations over 17 Years at 43 GHz (2018, background): “While X-ray images from Chandra (Marshall et al. 2002; Wilson & Yang 2002) are not of comparable resolution to the radio or optical, the same bright knots and overall jet structure can easily be seen in the X-rays.”
Dynamics and high-energy emission of the flaring HST-1 knot in the M 87 jet (2006, background): “Both its optical and its X-ray emissions are synchrotron in origin, similar to the inner parts of the outflow (Biretta, Stern & Harris 1991; Meisenheimer, Röser & Schlötelburg 1996; Sparks, Biretta & Macchetto 1996; Perlman et al. 1999, 2001; Marshall et al. 2002; Wilson & Yang 2002).”
Radio-X-Ray Correlation and the “Quiescent State” of Black Hole Sources (2004, background): “However, a subsequent Chandra observation strongly implies that the emission is dominated by the jet, as argued by Wilson & Yang (2002) based on the similarity of the X-ray spectra between the nucleus and jet knots.”
X-Ray Emission from Extragalactic Jets (2006, unknown): “…& Taylor (2002); 8 Birkinshaw, Worrall & Hardcastle (2002); 9 Zezas et al. (2005); 10 Chiaberge et al. (2003); 11 Harris et al. (2002); 12 Wilson & Yang (2002); 13 Marshall et al. (2002); 14 Hardcastle et al. (2003); 15 Marshall et al. (2005); 16 Hardcastle et al. (2005); 17 Evans et al.…”
Accretion onto the Supermassive Black Hole in M87 (2002, methodology): “…for the deprojected fit of 3171 for 1271 degrees of freedom indicates that the simple, spherically symmetric model provides an incomplete description of the Chandra data, which is not surprising given the structural complexities evident in Figure 1 (see also Wilson & Yang 2002; Young et al. 2002).”
X-Ray Emission Properties of Large-Scale Jets, Hot Spots, and Lobes in Active Galactic Nuclei (2004, background): “…spectrum of the jet-knots is consistent with a single smoothly broken power-law continuum, suggesting that this broad-band emission is entirely due to non-thermal synchrotron radiation from a single electron population (e.g., Marshall et al. 2002 and Wilson & Yang 2002 for M 87).”
A Chandra observation of the X-ray environment and jet of 3C 296 (2002, methodology): “1 shows, both the X-ray and radio emission from the jet are comparatively smooth, with little sign of the knotty structure seen in M87 or 3C 66B.”
Chandra and XMM-Newton Observations of a Sample of Low-Redshift FR I and FR II Radio Galaxy Nuclei (2005, background): “The power-law photon indices and normalizations are consistent, although Wilson & Yang (2002) found evidence for slight additional absorption (NH ¼ 3:5þ1:5 1:4 ; 1020 atoms cm 2) at the redshift of M87.”
Hot Accretion Flows Around Black Holes (2014, background): “However, Chandra observations suggest that the emission is dominated by the jet (Wilson & Yang 2002), which is consistent since M87 has LX LX,crit.”
The size of the jet launching region in M87 (2011, background): “…non-thermal jet spectrum to the X-ray does not significantly change its bolometric luminosity, but including Compton scattering would both increase the bolometric luminosity c© 2011 RAS, MNRAS 000, 1–13 and allow us to include a constraint from the observed X-ray luminosity (Wilson & Yang 2002).”
Radio and X-Ray Observations of the Jet in Centaurus A (2003, background): “However, the detection of X-ray emission from these regions (in addition to Cen A, the inner jets of M87 [Wilson & Yang 2002] and 3C 66B [Hardcastle et al. 2001] have been detected in the X-ray) is of interest because, if it is synchrotron in origin, it shows that this region of the jetis still…”