Tracing the Milky Way's Vestigial Nuclear Jet

Cecil, Gerald; Wagner, Alexander Y.; Bland-Hawthorn, Joss; Bicknell, Geoffrey V.; Mukherjee, Dipanjan

doi:10.48550/arxiv.2109.00901

Cited by 2 publications

(3 citation statements)

References 77 publications

(99 reference statements)

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“…Several recent works have shown strong evidence for an accretion-fed jet-type (collimated) event at the origin of the FBs, similar to jets in AGNs despite orders of magnitude of difference in power (e.g. [21,22]). The jets are collimated by the dense gas from the Central Molecular Zone (CMZ), which explains the FBs orientation at right angle from the Plane.…”

Section: The East-west Asymmetrymentioning

confidence: 91%

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North Polar Spur/Loop I: gigantic outskirt of the Northern Fermi bubble or nearby hot gas cavity blown by supernovae?

Lallement¹

2022

Preprint

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Radio continuum, microwave and gamma-ray images of the Milky Way reveal a conspicuous, looplike structure that fills almost half of the northern Galactic hemisphere, called Loop I. The interior of Loop I is the most conspicuous region shining in soft X-rays, whose eastern base is a remarkably bright, elongated structure seeming to emerge from the Galactic plane, dubbed the North Polar Spur (NPS). After 40 years of debates, two very different, contradictory views of Loop I/NPS are still defended: on the one hand, the NPS is a gigantic volume of expanding hot gas that envelops and extends the northern "Fermi Bubble" (FB) known to be blown by the Galactic center, and Loop I marks the shock front; on the other hand, the NPS is totally independent of the northern FB, it is a nearby, ordinary cavity of hot gas blown by supernovae, Loop I is its shock front and both are coincidentally located in the direction of the FB. To an observer at the Sun, both can produce the same perspective view, although the former has a size comparable to the Milky Way itself, and the latter a diameter of a few hundreds parsecs. The energy involved varies by 3-4 orders of magnitude, and the solution has important consequences on the structure and history of our Galactic neighborhood, on the age of the North and South FBs and the activity at the Galactic center. Moreover, whatever are the actual shape and distance of Loop I/NPS, accurate modeling of the polarized emission associated with Loop I is important for CMB foreground removal. After a short review, I discuss recent results which have a connection with Loop I/NPS. Some of them have been used as arguments in the two opposite ways, while for others the connections with LoopI/NPS have been overlooked. They involve very different spacecraft, from a 12 Kg Cubesat (HaloSat) to major space-borne observatories (HST, Gaia, and Spektr-RG). I make use of updated 3D maps of dust and a recent massive star catalog. I distinguish arguments based on geometric similarity or dissimilarity from those derived from measurements and physical models. Considering all past and recent constraints, it is clear that there is no entirely local or entirely distant scenario that is free from contradictions with some of the data analyses or from improbable coincidences. I discuss a speculative scenario, partially inspired by recent BF and Milky Way gas models, combining near and far aspects and seeming to be able to meet the various constraints. However, new data and models are needed to bring the controversy to a close and we can still expect new episodes of this long story.

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Section: The East-west Asymmetrymentioning

confidence: 91%

“…A series of X-ray, radio and IR data recently confirmed the existence of powerful jet-type outflows from the central parsecs at the GC, able to feed FB-type structures and suggesting that today's FBs are the result of a particularly strong activity several Myrs ago (see e.g. [21,22]).…”

Section: The Fermi Bubbles Discoverymentioning

confidence: 99%

North Polar Spur/Loop I: gigantic outskirt of the Northern Fermi bubble or nearby hot gas cavity blown by supernovae?

Lallement¹

2022

Preprint

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“…Generally speaking, the directions of SMBH jets are determined by the orientation of accretion disks and/or the black hole spins on much smaller scales and do not need to align with the rotational axis of the host galaxies. Future studies would be required to see whether this condition could be relaxed by considering tilted jets interacting with dense, multiphase interstellar medium within the Galactic disk 58 . Alternatively, such alignment may indeed be expected in low-mass, disky galaxies like the Milky Way, as shown by recent simulations 59 .…”

Section: Uncertainties and Limitations Of The Current Modelmentioning

confidence: 99%

Fermi and eRosita bubbles as relics of the past activity of the Galactic black hole

Yang,

Ruszkowski,

Zweibel

2022

Preprint

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The newly launched X-ray satellite, eRosita, has recently revealed two gigantic bubbles extending to ∼ 80 • above and below the Galactic center. The morphology of these "eRosita bubbles" bears a remarkable resemblance to the Fermi bubbles previously discovered by the Fermi Gamma-ray Space Telescope and its counterpart, the microwave haze. The physical origin of these striking structures has been intensely debated; however, because of their symmetry about the Galactic center, they likely originate from some energetic outbursts from the Galactic center in the past. Here we propose a theoretical model in which the eRosita bubbles, Fermi bubbles, and the microwave haze could be simultaneously explained by a single event of jet activity from the central supermassive black hole a few million years ago. Using numerical simulations, we show that this model could successfully reproduce the morphology and multi-wavelength spectra of the observed bubbles and haze, which allows us to derive critical constraints on the energetics and timescales of the outburst. This study serves as an important step forward in our understanding of the past Galactic center activity of our Milky Way Galaxy, and may bring valuable insights into the broader picture of supermassive black hole-galaxy co-evolution in the context of galaxy formation.Recent data taken by the eRosita satellite has revealed striking images of two giant X-ray bubbles extending ∼ 80 • (which corresponds to ∼ 15 kpc assuming a distance to the Galactic Center (GC) of 8.5kpc) above and below the GC 1 . Despite the larger extent, the morphology of the "eRosita bubbles" is remarkably similar to the Fermi bubbles, the two gamma-ray bubbles detected by the Fermi Gamma-ray Space Telescope in 2010 2 . It was also shown previously that the gamma-ray bubbles have counterparts in the microwave band, known as the microwave/WMAP/Planck haze 3,4 , as well as polarized lobes in radio 5 . The

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Tracing the Milky Way's Vestigial Nuclear Jet

Cited by 2 publications

References 77 publications

North Polar Spur/Loop I: gigantic outskirt of the Northern Fermi bubble or nearby hot gas cavity blown by supernovae?

North Polar Spur/Loop I: gigantic outskirt of the Northern Fermi bubble or nearby hot gas cavity blown by supernovae?

Fermi and eRosita bubbles as relics of the past activity of the Galactic black hole

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