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Cosmic rays (CR) play an important role in dense molecular cores, affecting their thermal and dynamical evolution and initiating the chemistry. Several studies have shown that the formation of protostellar discs in collapsing clouds is…

Astrophysics of Galaxies · Physics 2015-06-17 Marco Padovani , Patrick Hennebelle , Daniele Galli

We present the first systematic study of the density structure of clouds found in a complete sample covering all major molecular clouds in the Central Molecular Zone (CMZ; inner $\sim{}200~\rm{}pc$) of the Milky Way. This is made possible…

Chemistry in diffuse molecular clouds relies primarily on rapid ion-molecule reactions. Formation of the initial ions, H$^+$ and H$_2^+$, is dominated by cosmic-ray ionization of H and H$_2$, making the cosmic-ray ionization rate (denoted…

The region bounded by the inner tens of light years at the center of the Milky Way contains five principal components that coexist within the central deep gravitational potential well. These constituents are a black hole candidate (Sgr~A*)…

Astrophysics · Physics 2015-06-24 F. Yusef-Zade , F. Melia , M. Wardle

Infrared absorption lines of H3+, including the metastable R(3,3)l line, have been observed toward eight bright infrared sources associated with hot and massive stars located in and between the Galactic Center Cluster and the Quintuplet…

Molecular clouds act as targets for cosmic rays (CR), revealing their presence through either gamma-ray emission due to proton-proton interactions, and/or through the ionization level in the cloud, produced by the CR flux. The ionization…

High Energy Astrophysical Phenomena · Physics 2015-07-21 Julian Krause , Giovanni Morlino , Stefano Gabici

To determine the properties of the ionized gas at the edge of the CMZ near Sgr E we observed a small portion of the edge of the CMZ near Sgr E with spectrally resolved [C II] 158 micron and [N II] 205 micron fine structure lines at six…

Astrophysics of Galaxies · Physics 2015-06-23 W. D. Langer , P. F. Goldsmith , J. L. Pineda , T. Velusamy , M. A. Requena-Torres , H. Wiesemeyer

The Galactic centre - as the closest galactic nucleus - holds both intrinsic interest and possibly represents a useful analogue to star-burst nuclei which we can observe with orders of magnitude finer detail than these external systems. The…

Astrophysics of Galaxies · Physics 2015-06-03 Roland M. Crocker

The energy densities in magnetic fields and cosmic rays (CRs) in galaxies are often assumed to be in equipartition, allowing for an indirect estimate of the magnetic field strength from the observed radio synchrotron spectrum. However, both…

Astrophysics of Galaxies · Physics 2016-01-27 Tova M. Yoast-Hull , John S. Gallagher , Ellen G. Zweibel

The center of the Galaxy is a prominent source in X-rays and gamma-rays. The study of its high-energy (HE) emission is crucial in understanding the physical phenomena taking place in this dense and extreme environment, where the closest…

High Energy Astrophysical Phenomena · Physics 2026-02-17 Andrea Goldwurm , Maïca Clavel , Stefano Gabici , Régis Terrier

The Milky Way centre hosts a supermassive Black Hole (BH) with a mass of ~4*10^6 M_Sun. Sgr A*, its electromagnetic counterpart, currently appears as an extremely weak source with a luminosity L~10^-9 L_Edd. The lowest known Eddington ratio…

Astrophysics of Galaxies · Physics 2015-06-11 Gabriele Ponti , Mark R. Morris , Regis Terrier , Andrea Goldwurm

It was recently discovered that in some regions of the Galaxy, the cosmic ray (CR) abundance is several orders of magnitude higher than previously thought. Additionally, there is evidence that in molecular cloud envelopes, the CR ionization…

High Energy Astrophysical Phenomena · Physics 2020-10-21 Kedron Silsbee , Alexei V. Ivlev

The Central Molecular Zone (CMZ) of the Milky Way is fed by gas inflows from the Galactic disk along almost radial trajectories aligned with the major axis of the Galactic bar. However, despite being fundamental to all processes in the…

Recent results from the HESS gamma ray telescope have shown the presence of both a diffuse, extended, flux of gamma rays above ~0.4 TeV and discrete sources in and near the Galactic Centre. Here, we put forward a possible explanation in…

Astrophysics · Physics 2009-06-23 A. D. Erlykin , A. W. Wolfendale

We demonstrate that the anomalous ionization rate observed in the Central Molecular Zone can be attributed to MeV dark matter annihilations into $e^+e^-$ pairs for galactic dark matter profiles with slopes $\gamma>1$. The low annihilation…

High Energy Physics - Phenomenology · Physics 2025-03-19 Pedro De la Torre Luque , Shyam Balaji , Joseph Silk

Using an absorption line from the metastable (J, K) = (3, 3) level of H3+ together with other lines of H3+ and CO observed along several sightlines, we have discovered a vast amount of high temperature (T ~ 250 K) and low density (n ~ 100…

Astrophysics · Physics 2016-08-30 Takeshi Oka , T. R. Geballe , Miwa Goto , Tomonori Usuda , B. J. McCall

We present the first detection of complex aldehydes and isomers in three typical molecular clouds located within 200pc of the center of our Galaxy. We find very large abundances of these complex organic molecules (COMs) in the central…

Astrophysics · Physics 2009-11-13 M. A. Requena-Torres , J. Martin-Pintado , S. Martin , M. R. Morris

We present a study of the gas cycle and star formation history in the central 500 pc of the Milky Way, known as Central Molecular Zone (CMZ). Through hydrodynamical simulations of the inner 4.5 kpc of our Galaxy, we follow the gas cycle in…

Astrophysics of Galaxies · Physics 2019-10-23 L. Armillotta , M. R. Krumholz , E. M. Di Teodoro , N. M. McClure-Griffiths

Our goal is to estimate the total gas mass in the direction of the Central Molecular Zone (CMZ), quantify the various uncertainties associated, and discuss the implications for the estimates of CR energy densities and dust opacities. The…

Astrophysics of Galaxies · Physics 2025-05-07 H. X. Ren , Q. Remy , S. Ravikularaman , M. Bouyahiaoui , F. Conte , J. Djuvsland