X-Ray Properties of the Nucleus of M81

Ishisaki, Yoshitaka; Makishima, Kazuo; Iyomoto, Naoko; Hayashida, Kentaro; Inoue, Hajime; Mitsuda, Kazuhisa; Tanaka, Yasuo; Uno, S.; Kohmura, Yoshiki; Mushotzky, R. F.; Petre, Robert; Serlemitsos, P. J.; Terashima, Yuichi

doi:10.1093/pasj/48.2.237

Cited by 96 publications

(116 citation statements)

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“…ASCA measurements suggest that spiral galaxies often host nuclear LLAGN with L 0.5−10 keV ∼ 10 40 − 10 41 erg s −1 (Ishisaki et al 1996). ROSAT/HRI detections of short-time variability (Collura et al 1994) support this view.…”

Section: Compact Nucleusmentioning

confidence: 91%

X-ray spectral components of starburst galaxies

Peršić

Rephaeli

2002

A&A

124

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Abstract. X-ray emission processes in starburst galaxies (SBGs) are assessed, with the aim of identifying and characterizing the main spectral components. Our survey of spectral properties, complemented with a model for the evolution of galactic stellar populations, leads to the prediction of a complex spectrum. Comparing the predicted spectral properties with current X-ray measurements of the nearby SBGs M 82 and N253, we draw the following tentative conclusions: 1) X-ray binaries with accreting neutron stars are the main contributors in the 2-15 keV band, and could be responsible for the yet uninterpreted hard component required to fit the observed 0.5-10 keV spectra of SBGs; 2) diffuse thermal plasma contributes at energies < ∼ 1 keV; 3) nonthermal emission, from Compton scattering of FIR and CMB radiation fields photons off supernova-accelerated relativistic electrons, and AGN-like emission, are likely be the dominant emission at energies > ∼ 30 keV; 4) supernova remnants make a relatively minor contribution to the X-ray continuum but may contribute appreciably to the Fe-K emission at 6.7 keV.

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Section: Compact Nucleusmentioning

confidence: 91%

X-ray spectral components of starburst galaxies

Peršić

Rephaeli

2002

A&A

124

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“…The X-ray spectral properties of LLAGNs, particularly LINERs, have most thoroughly been investigated using ASCA (Yaqoob et al 1995;Ishisaki et al 1996;Iyomoto et al 1996Iyomoto et al , 1997Iyomoto et al , 1998aIyomoto et al , 1998bPtak et al 1996Ptak et al , 1999Terashima et al 1998aTerashima et al , 1998bTerashima et al , 2000aTerashima et al , 2000bTerashima et al , 2002Ho et al 1999a;Terashima, Ho & Ptak 2000;Roberts, Schurch & Warwick 2001), with important contributions from BeppoSAX (Pellegrini et al 2000a(Pellegrini et al , 2000b(Pellegrini et al , 2002Iyomoto et al 2001;Georgantopoulos et al 2002;Ptak et al 2004). A seminal study on M81 was done using BBXRT (Petre et al 1993).…”

Section: X-ray Coresmentioning

confidence: 99%

Nuclear Activity in Nearby Galaxies

2008

Annu. Rev. Astron. Astrophys.

1,123

104

1,195

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A significant fraction of nearby galaxies show evidence of weak nuclear activity unrelated to normal stellar processes. Recent high-resolution, multiwavelength observations indicate that the bulk of this activity derives from black hole accretion with a wide range of accretion rates. The low accretion rates that typify most low-luminosity active galactic nuclei induce significant modifications to their central engine. The broad-line region and obscuring torus disappear in some of the faintest sources, and the optically thick accretion disk transforms into a three-component structure consisting of an inner radiatively inefficient accretion flow, a truncated outer thin disk, and a jet or outflow. The local census of nuclear activity supports the notion that most, perhaps all, bulges host a central supermassive black hole, although the existence of active nuclei in at least some late-type galaxies suggests that a classical bulge is not a prerequisite to seed a nuclear black hole.

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“…The flux density of the AGN in M 81 (hereafter, M 81*), has relatively large variability, from X-rays (Ishisaki et al 1996;Page et al 1994) to radio wavelengths (Ho et al 1999;, at centimeter wavelengths; Schödel et al 2007, at millimeter wavelengths). The variability time scale runs from years to days, indicating a contribution from a very compact source to the emission at all frequencies.…”

Section: Introductionmentioning

confidence: 99%

Detection of jet precession in the active nucleus of M 81

Martí-Vidal

Marcaide

Alberdi

et al. 2011

A&A

105

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We report on very-long-baseline-interferometry (VLBI) monitoring observations of the low-luminosity active galactic nucleus (LLAGN) in the galaxy M 81 at the frequencies of 1.7, 2.3, 5.0, and 8.4 GHz. The observations reported here are phase-referenced to the supernova SN 1993J (located in the same galaxy) and cover from late 1993 to late 2005. The large amount of available observations allows us to study the stability of the AGN position in the frame of its host galaxy at different frequencies and chromatic effects in the jet morphology, together with their time evolution. The source consists at all frequencies of a slightly resolved core and a small jet extension towards the northeast direction (position angle of ∼65 degrees) in agreement with previous publications. We find that the position of the intensity peak in the images at 8.4 GHz is very stable in the galactic frame of M 81 (proper motion upper limit about 10 μas per year). We confirm previous reports that the peaks at all frequencies are systematically shifted among them, possibly due to opacity effects in the jet as predicted by the standard relativistic jet model. We use this model, under plausible assumptions, to estimate the magnetic field in the jet close to the jet base and the mass of the central black hole. We obtain a black-hole mass of ∼2 × 10 7 M , comparable to estimates previously reported using different approaches, but the magnetic fields obtained are 10 3 −10 4 times lower than previous estimates. We find that the positions of the cores at 1.7, 2.3, and 5.0 GHz are less stable than that at 8.4 GHz and evolve systematically, shifting southward at a rate of several tens of μas per year. The evolution in the jet orientation seems to be related to changes in the inclination of the cores at all frequencies. These results can be interpreted as due to a precessing jet. The evolving jet orientation also seems to be related to a flare in the peak flux densities at 5.0 and 8.4 GHz, which lasts ∼4 years (from mid 1997 to mid 2001). An increase in the accretion rate of the black hole, and its correlation with the jet luminosity via the disk-jet connection model, seems insufficient to explain this long flare and the simultaneous evolution in the jet orientation. A continued monitoring of the flux density and the jet structure evolution in this LLAGN will be necessary to further confirm our jet precession model.

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X-Ray Properties of the Nucleus of M81

Cited by 96 publications

References 0 publications

X-ray spectral components of starburst galaxies

X-ray spectral components of starburst galaxies

Nuclear Activity in Nearby Galaxies

Detection of jet precession in the active nucleus of M 81

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