Transonic galactic outflows in a dark matter halo with a central black hole and its application to the Sombrero galaxy

Igarashi, Asuka; Mori, Masao; Nitta, S.

doi:10.1093/mnras/stu1466

Cited by 9 publications

(30 citation statements)

References 68 publications

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“…Specifically, although the trace of the galactic outflow can be seen in X-ray observations, the gas density distribution in this galaxy is well reproduced as a hydrostatic state. Further, Igarashi et al (2014) have indicated that the hot gas of this galaxy may form a slowly accelerating transonic outflow. In the widely spread subsonic region, it is difficult to distinguish the gas density from a hydrostatic state.…”

Section: Introductionmentioning

confidence: 92%

“…2 and 4 of Tsuchiya et al 2013 or Fig. 1 of Igarashi et al 2014). In the type B solutions, it is plausible to consider that the outflow starts at the vicinity of the locus of the O-point (just below the O-point of type B in Fig.1).…”

Section: Transonic Solutions Incorporating Dmh Gravitational Potentialmentioning

confidence: 99%

“…3 and 4. As in Igarashi et al (2014), the gravitational potential of the SMBH adds a new branch to the transonic solutions yielded by the model discussed previously, which incorporated the effects of the DMH gravitational potential only. We determine two primary types of transonic solution: One having only one X-point (type A) and the other having two X-points with a single O-point (type B).…”

Section: Transonic Solutions Incorporating Gravitational Potentials Omentioning

confidence: 99%

“…Therefore, Igarashi et al (2014) added the gravitational potential of the central SMBH to the Tsuchiya model, because the original Tsuchiya model considers the DMH gravitational potential only. They summarised the variety of transonic solutions under realistic mass distributions incorporating the gravitational potentials of both the DMH and SMBH, and applied their model to the Sombrero Galaxy (NGC4594) to clarify the acceleration process of the galactic outflows.…”

Section: Introductionmentioning

confidence: 99%

“…However, the isothermal approximation adopted by Igarashi et al (2014) and Tsuchiya et al (2013) is not universally applicable to galaxies. For example, the isothermal model results in a larger amount of outflowing gas than can be supplied by SNe and stellar winds.…”

Section: Introductionmentioning

confidence: 99%

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Polytropic transonic galactic outflows in a dark matter halo with a central black hole

Igarashi

Mori

Nitta

2017

Monthly Notices of the Royal Astronomical Society

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Polytropic transonic solutions of spherically symmetric and steady galactic winds in the gravitational potential of a dark matter halo (DMH) with a supermassive black hole (SMBH) are studied. The solutions are classified in terms of their topological features, and the gravitational potential of the SMBH adds a new branch to the transonic solutions generated by the gravity of the DMH. The topological types of the transonic solutions depend on the mass distribution, the amount of supplied energy, the polytropic index γ, and the slope α of the DMH mass distribution. When α becomes larger than a critical value α c , the transonic solution types change dramatically. Further, our model predicts that it is possible for a slowly accelerating outflow to exist, even in quiescent galaxies with small γ. This slowly accelerating outflow differs from those considered in many of the previous studies focusing on supersonic outflows in active star-forming galaxies. In addition, our model indicates that outflows in active star-forming galaxies have only one transonic point in the inner region (∼ 0.01 kpc). The locus of this transonic point does not strongly depend on γ. We apply the polytropic model incorporating mass flux supplied by stellar components to the Sombrero Galaxy, and conclude that it can reproduce the observed gas density and the temperature distribution well. This result differs significantly from the isothermal model, which requires an unrealistically large mass flux (Igarashi et al. 2014). Thus, we conclude that the polytropic model is more realistic than the isothermal model, and that the Sombrero Galaxy can have a slowly accelerating outflow.

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Section: Introductionmentioning

confidence: 92%

Section: Transonic Solutions Incorporating Dmh Gravitational Potentialmentioning

confidence: 99%

Section: Transonic Solutions Incorporating Gravitational Potentials Omentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Polytropic transonic galactic outflows in a dark matter halo with a central black hole

Igarashi

Mori

Nitta

2017

Monthly Notices of the Royal Astronomical Society

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Transonic galactic outflows in a dark matter halo with a central black hole

2015

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We study fundamental properties of transonic galactic outflows in the gravitational potential of a cold dark matter halo (DMH) with a central super-massive black hole (SMBH) assuming an isothermal, steady and spherically symmetric state. Transonic solutions of galactic outflows are classified according to their topological features. As result, we find two types of transonic solutions distinguished by a magnitude relationship between the gravity of DMH and that of SMBH. The loci of transonic points for two types are different; one transonic point is formed at a central region (< 0.01kpc) and another is at a very distant region (> 100kpc). Also, mass fluxes and outflow velocities are different for two solutions. Thus, these solutions may differently influence the evolution of galaxies and the release of metals into the intergalactic space.Furthermore, we apply our model to the Sombrero galaxy. In this galaxy, the wide-spread hot gas is detected as the trace of galactic outflows while the star-formation rate is low, and the observed gas density distribution is similar to the hydrostatic state (Li et al. 2011). To solve this discrepancy, we propose a solution that this galaxy has a slowly accelerating outflow; the transonic point forms in a very distant region (~ 120 kpc) and the wide subsonic region spreads across the stellar distribution. Thus, the gas density distribution in the observed region is similar to the hydrostatic state. Such slowly accelerating outflows are different from high-velocity outflows conventionally studied (Igarashi et al. 2014).However, this isothermal model requires an unrealistically large mass flux. Then, we apply the polytropic model to this galaxy incorporating mass flux supplied by stellar components. We find that it can reproduce the observed gas density and the temperature distributions with the realistic mass flux. Thus, our polytropic model successfully demonstrates the existence of the slowly accelerating outflow in the Sombrero galaxy (Igarashi et al. 2015).

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A new concept of transonic galactic outflows and its application to the Sombrero galaxy

2016

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We study fundamental properties of transonic galactic outflows in the gravitational potential of a cold dark matter halo (DMH) with a central super-massive black hole (SMBH) assuming a polytropic, steady and spherically symmetric state. We have classified the transonic solutions with respect to their topology in the phase space. As a result, we have found two types of transonic solutions characterized by a magnitude relationship between the gravity of DMH and that of SMBH. These two types of solutions have different loci of the transonic points; one transonic point is formed at a central region (< 0.01kpc) and another is at a distant region (> 100kpc). Also, mass fluxes and outflow velocities are different between the two solutions. These two transonic solutions may play different roles on the star formation history of galaxies and the metal contamination of intergalactic space. Furthermore, we have applied our model to the Sombrero galaxy. In this galaxy, the wide-spread hot gas is detected as an apparent trace of galactic outflows while the star-formation rate is disproportionately low, and the observed gas density distribution is quite similar to the hydrostatic state (Li et al. 2011). To solve this discrepancy, we propose a slowly accelerating outflow in which the transonic point forms in a distant region (~ 120 kpc) and the subsonic region spreads across the stellar distribution. In the subsonic region, the gas density distribution is similar to that of the hydrostatic state. Our model predicts the possibility of the slowly accelerating outflow in the Sombrero galaxy. Igarashi et al. 2014 used the isothermal model and well reproduced the observed gas density distribution, but the estimated mass flux (1.8M⊙/yr) is lager than the mass of the gas supplied by stars (0.3-0.4M⊙/yr). Then, we expect that the polytropic model may reproduce the observational mass of the supplied gas (Igarashi et al. 2015). Such slowly accelerating outflows should be distinguished from the conventional supersonic outflows frequently argued in star-forming galaxies.

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Transonic galactic outflows in a dark matter halo with a central black hole and its application to the Sombrero galaxy

Cited by 9 publications

References 68 publications

Polytropic transonic galactic outflows in a dark matter halo with a central black hole

Polytropic transonic galactic outflows in a dark matter halo with a central black hole

Transonic galactic outflows in a dark matter halo with a central black hole

A new concept of transonic galactic outflows and its application to the Sombrero galaxy

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