The search for the origin of the Local Bubble redivivus

Fuchs, B.; Breitschwerdt, D.; Avillez, Miguel A. de; Dettbarn, C.; Flynn, Chris

doi:10.1111/j.1365-2966.2006.11044.x

Cited by 124 publications

(131 citation statements)

References 39 publications

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“…It is widely believed that the Local Hot Bubble and Local Cavity are the result of one or more supernova (SN) explosions (Cox and Anderson 1982), but in an alternate scenario this superbubble picture is disputed, and it is instead the rarefied Local Cavity that is thought to be caused by star formation epochs in the Scorpius-Centaurus OB association as regulated by the nearby spiral arm configuration (Bochkarev 1987;Frisch 1995;Fuchs et al 2006;Maiz-Apellaniz 2001). Other suggested Local Cavity formation scenarios involve an association with the young and massive stars of the Gould Belt (Grenier 2000) or the passage of a high velocity cloud through the galactic disk (Comeron and Torra 1994).…”

Section: Kinematics Of the Local Cavity Gasmentioning

confidence: 99%

The trouble with the Local Bubble

Welsh

Shelton

2009

Astrophys Space Sci

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The model of a Local Hot Bubble has been widely accepted as providing a framework that can explain the ubiquitous presence of the soft X-ray background diffuse emission. We summarize the current knowledge on this local interstellar region, paying particular reference to observations that sample emission from the presumed local million degree K hot plasma. However, we have listed numerous observations that are seemingly in conflict with the concept of a hot Local Bubble. In particular, the discovery of solar wind charge exchange that can generate an appreciable soft X-ray background signal within the heliosphere, has led to a reassessment of the generally accepted model that requires a hot local plasma.In order to explain the majority of observations of the local plasma, we forward two new speculative models that describe the physical state of the local interstellar gas. One possible scenario is similar to the present widely accepted model of the Local Hot Bubble, except that it accounts for only 50% of the soft X-ray emission currently detected in the galactic plane, has a lower thermal pressure than previously thought, and its hot plasma is not as hot as previously believed. Although such a model can solve several difficulties with the traditional hot Local Bubble model, a heating mechanism for the dimmer and cooler gas remains to be found. The second possible explanation is that of the 'Hot Top' model, in which the Local Cavity is an old su-B.Y. Welsh ( ) Space Sciences Laboratory, University of California, 7 Gauss Way, Berkeley, CA 94720, USA e-mail: bwelsh@ssl.berkeley.edu R.L. Shelton Department of Physics and Astronomy, University of Georgia, Athens, GA 30602, USA pernova remnant in which no (or very little) million degree local plasma is presently required. Instead, the cavity is now thought to be filled with partially ionized cloudlets of temperature ∼ 7000 K that are surrounded by lower density envelopes of photo-ionized gas of temperature ∼ 20,000 K. Although this new scenario provides a natural explanation for many of the observations that were in conflict with the Local Hot Bubble model, we cannot (as yet) provide a satisfactory explanation or the emission levels observed in the B and Be ultra-soft X-ray bands.

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Section: Kinematics Of the Local Cavity Gasmentioning

confidence: 99%

The trouble with the Local Bubble

Welsh

Shelton

2009

Astrophys Space Sci

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“…Their times of explosion are calculated by a formula for the main sequence life time [29]. The trajectory of the stars has been calculated backwards in time using Hipparcos data for positions and proper motions, and ARIVEL data for radial velocities (for details see Berghöfer & Breitschwerdt [6] and Fuchs et al [16]). The results are based on the solution of the hydrodynamic fluid equations, including: (i) a gravitational field of the stellar disk [19], (ii) radiative cooling assuming CIE and solar abundances (for T ≥ 10 4 K we use Sutherland & Dopita [30] and for 10 < T < 10 4 K Dalgarno & McCray [12], corrected for solar abundances taken from Anders & Grevesse [1]), and (iii) uniform background heating due to starlight varying with z [31].…”

Section: Numerical Modelingmentioning

confidence: 99%

“…For the time-dependent energy input rate, we have taken an initial mass function (IMF) with a slope of Γ = −1.1 [22], and for the main-sequence life-time of massive stars we applied the more recent approximation by Fuchs et al [16], relating the main sequence life time to stellar mass by τ ms = τ 0 M −α , with τ 0 = 1.6 × 10 8 yr and α = 0.932, for 2 < M < 67 (with M in units of M ⊙ ; for further details, see MSc thesis by Baumgartner [5]). All SNe are assumed to explode in the center of the bubble (r = 0, z = 0).…”

Section: Analytical Modelingmentioning

confidence: 99%

“…In summary, it seems reasonable to assume that multiple SN explosions are responsible for a significant amount of the soft X-ray and UV emitting plasma, and to search for the origin of the "smoking gun", because there is no young stellar cluster found inside the LB. Investigating moving groups of the local ISM (Berghöfer & Breitschwerdt [6]), which was later extended to a complete and unbiased analysis of Hipparcos data of a larger volume of 400 pc in diameter, and combining these data by ARIVEL catalogue data (Fuchs et al [16]), it turned out that indeed a moving group crossed the present day LB region about 10 -15 Myr ago, with its surviving members being now part of the Sco Cen association (see also [21]). During this passage about 14 to 19 SNe exploded and energized the LB.…”

Section: Introductionmentioning

confidence: 99%

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Modeling the Local Warm∕Hot Bubble

Breitschwerdt¹,

Avillez²,

Baumgartner³

2009

AIP Conference Proceedings

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Abstract. In this paper we review the modeling of the Local Bubble (LB) with special emphasis on the progress we have made since the last major conference "The Local Bubble and Beyond (I)" held in Garching in 1997. Since then new insight was gained into the possible origin of the LB, with a moving group crossing its volume during the last 10 -15 Myr being most likely responsible for creating a local cavity filled with hot recombining gas. Numerical high resolution 3D simulations of a supernova driven inhomogeneous interstellar medium show that we can reproduce both the extension of the LB and the OVI column density in absorption measured with FUSE for a LB age of 13.5 -14.5 Myr. We further demonstrate that the LB evolves like an ordinary superbubble expanding into a density stratified medium by comparing analytical 2D Kompaneets solutions to NaI contours, representing the extension of the local cavity. These results suggest that LB blow-out into the Milky Way halo has occurred roughly 5 Myr ago.

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“…Frisch 1981Frisch , 1995Frisch and York 1986;Bochkarev 1987;Maíz-Apellániz 2001;Fuchs et al 2006;Wolleben 2007;. Shells swept up by the winds of young stars in the ScorpiusCentaurus Association may be coincident with the location of the Sun today, and may be responsible for the very local warm ISMa clouds observed in our immediate vicinity.…”

Section: Origin Of Local Interstellar Mediummentioning

confidence: 99%

The Galactic Environment of the Sun: Interstellar Material Inside and Outside of the Heliosphere

et al. 2009

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Interstellar material (ISMa) is observed both inside and outside of the heliosphere. Relating these diverse sets of ISMa data provides a richer understanding of both the interstellar medium and the heliosphere. The galactic environment of the Sun is dominated by warm, low-density, partially ionized interstellar material consisting of atoms and dust grains. The properties of the heliosphere are dependent on the pressure, composition, radiation field, ionization, and magnetic field of ambient ISMa. The very low-density interior of the Local Bubble, combined with an expanding superbubble shell associated with star formation in the Scorpius-Centaurus Association, dominate the properties of the local interstellar medium (LISM). Once the heliosphere boundaries and interaction mechanisms are understood, interstellar gas, dust, pickup ions, and anomalous cosmic rays inside of the heliosphere can be directly compared to ISMa outside of the heliosphere. Our understanding of ISMa at the Sun is further enriched when the circumheliospheric interstellar material is compared to observations of other nearby ISMa and the overall context of our galactic environment. The IBEX mission will map the interaction region between the heliosphere and ISMa, and improve the accuracy of comparisons between ISMa inside and outside the heliosphere.

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The search for the origin of the Local Bubble redivivus

Cited by 124 publications

References 39 publications

The trouble with the Local Bubble

The trouble with the Local Bubble

Modeling the Local Warm∕Hot Bubble

The Galactic Environment of the Sun: Interstellar Material Inside and Outside of the Heliosphere

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