scholarly journals The Galactic center: a model for cosmic ray interactions in starburst galaxies?

2013 ◽  
Vol 9 (S303) ◽  
pp. 153-155
Author(s):  
T. Yoast-Hull ◽  
J. S. Gallagher ◽  
E. Zweibel
Keyword(s):  
Galactic Center ◽  
Cosmic Ray ◽  
Starburst Galaxies ◽  
Starburst Galaxy ◽  
Published Data ◽  
Molecular Gas ◽  
Radiation Fields ◽  
Cosmic Ray Interactions ◽  
Close Proximity ◽  
Quantitative Basis

AbstractThe Galactic center contains strong magnetic fields, high radiation fields, and dense molecular gas, as is also the case in starburst galaxies. The close proximity of the Galactic center allows for more and better observations of the interstellar medium than for extragalactic sources making it an ideal place for testing models for cosmic ray interactions. We compare our semi-analytic model for cosmic ray interactions to published data for both the Galactic center and the starburst galaxy NGC 253. We present the predicted radio and γ-ray spectra and compare the results with published measurements. In this way we provide a quantitative basis for assessing the degree to which the Galactic center resembles a starburst system.

scholarly journals The cool and warm molecular gas in M82 with Herschel-SPIRE

2012 ◽  
Vol 10 (H16) ◽  
pp. 618-618
Author(s):  
J. Kamenetzky ◽  
J. Glenn ◽  
N. Rangwala ◽  
P. Maloney ◽  
M. Bradford ◽  
...  
Keyword(s):  
Column Density ◽  
Filling Factor ◽  
Imaging Spectroscopy ◽  
Cosmic Ray ◽  
Starburst Galaxy ◽  
Molecular Gas ◽  
Likelihood Analysis ◽  
J 13 ◽  
Turbulent Heating ◽  
Excitation Processes

AbstractWe present Herschel-SPIRE imaging spectroscopy (194-671 μm) of the bright starburst galaxy M82. We use RADEX and a Bayesian Likelihood Analysis to simultaneously model the temperature, density, column density, and filling factor of both the cool and warm components of molecular gas traced by the entire CO ladder up to J=13-12. The high-J lines observed by SPIRE trace much warmer gas (~500 K) than those observable from the ground. The addition of 13CO (and [C I]) is new and indicates that [C I] may be tracing different gas than 12CO. At such a high temperature, cooling is dominated by molecular hydrogen; we conclude with a discussion on the possible excitation processes in this warm component. Photon-dominated region (PDR) models require significantly higher densities than those indicated by our Bayesian likelihood analysis in order to explain the high-J CO line ratios, though cosmic-ray enhanced PDR models can do a better job reproducing the emission at lower densities. Shocks and turbulent heating are likely required to explain the bright high-J emission.

scholarly journals Starburst Energy Feedback Seen through HCO+/HOC+ Emission in NGC 253 from ALCHEMI

2021 ◽  
Vol 923 (1) ◽  
pp. 24
Author(s):  
Nanase Harada ◽  
Sergio Martín ◽  
Jeffrey G. Mangum ◽  
Kazushi Sakamoto ◽  
Sebastien Muller ◽  
...  
Keyword(s):  
Galactic Center ◽  
Cosmic Ray ◽  
Ionization Rate ◽  
High Energy ◽  
Photon Flux ◽  
Starburst Galaxy ◽  
Energy Feedback ◽  
The Difference ◽  
Uv Photons ◽  
Molecular Abundances

Abstract Molecular abundances are sensitive to the UV photon flux and cosmic-ray ionization rate. In starburst environments, the effects of high-energy photons and particles are expected to be stronger. We examine these astrochemical signatures through multiple transitions of HCO+ and its metastable isomer HOC+ in the center of the starburst galaxy NGC 253 using data from the Atacama Large Millimeter/submillimeter Array large program ALMA Comprehensive High-resolution Extragalactic Molecular inventory. The distribution of the HOC+(1−0) integrated intensity shows its association with “superbubbles,” cavities created either by supernovae or expanding H ii regions. The observed HCO+/HOC+ abundance ratios are ∼10–150, and the fractional abundance of HOC+ relative to H2 is ∼1.5 × 10−11–6 × 10−10, which implies that the HOC+ abundance in the center of NGC 253 is significantly higher than in quiescent spiral arm dark clouds in the Galaxy and the Galactic center clouds. Comparison with chemical models implies either an interstellar radiation field of G 0 ≳ 103 if the maximum visual extinction is ≳5, or a cosmic-ray ionization rate of ζ ≳ 10−14 s−1 (3–4 orders of magnitude higher than that within clouds in the Galactic spiral arms) to reproduce the observed results. From the difference in formation routes of HOC+, we propose that a low-excitation line of HOC+ traces cosmic-ray dominated regions, while high-excitation lines trace photodissociation regions. Our results suggest that the interstellar medium in the center of NGC 253 is significantly affected by energy input from UV photons and cosmic rays, sources of energy feedback.

scholarly journals A hydrodynamical study of outflows in starburst galaxies with different driving mechanisms

2020 ◽  
Vol 492 (3) ◽  
pp. 3179-3193 ◽  
Author(s):  
B P Brian Yu ◽  
Ellis R Owen ◽  
Kinwah Wu ◽  
Ignacio Ferreras
Keyword(s):  
Magnetic Field ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
Starburst Galaxies ◽  
Host Galaxy ◽  
Starburst Galaxy ◽  
Driving Mechanism ◽  
Driving Mechanisms ◽  
The Impact ◽  
Flow Velocities

ABSTRACT Outflows from starburst galaxies can be driven by thermal pressure, radiation, and cosmic rays. We present an analytic phenomenological model that accounts for these contributions simultaneously to investigate their effects on the hydrodynamical properties of outflows. We assess the impact of energy injection, wind opacity, magnetic field strength, and the mass of the host galaxy on flow velocity, temperature, density, and pressure profiles. For an M82-like wind, a thermally dominated driving mechanism is found to deliver the fastest and hottest wind. Radiation-driven winds in typical starburst-galaxy configurations are unable to attain the higher flow velocities and temperatures associated with thermal and cosmic ray-driven systems, leading to higher wind densities which would be more susceptible to cooling and fragmentation at lower altitudes. High opacity winds are more sensitive to radiative driving, but terminal flow velocities are still lower than those achieved by other driving mechanisms at realistic opacities. We demonstrate that variations in the outflow magnetic field can influence its coupling with cosmic rays, where stronger fields enable greater streaming but less driving near the base of the flow, instead with cosmic rays redirecting their driving impact to higher altitudes. The gravitational potential is less important in M82-like wind configurations, and substantial variations in the flow profiles only emerge at high altitude in massive haloes. This model offers a more generalized approach to examine the large-scale hydrodynamical properties for a wide variety of starburst galaxies.

Cosmic-ray-dominated dense molecular gas in normal and starburst galaxies

1993 ◽  
Vol 413 ◽  
pp. 542 ◽  
Author(s):  
Anatolij Suchkov ◽  
Ronald J. Allen ◽  
Timothy M. Heckman
Keyword(s):  
Cosmic Ray ◽  
Starburst Galaxies ◽  
Molecular Gas

scholarly journals CO emission in distant galaxies on and above the main sequence

2020 ◽  
Vol 641 ◽  
pp. A155 ◽  
Author(s):  
F. Valentino ◽  
E. Daddi ◽  
A. Puglisi ◽  
G. E. Magdis ◽  
D. Liu ◽  
...  
Keyword(s):  
Star Formation ◽  
Energy Distribution ◽  
Main Sequence ◽  
Spectral Energy Distribution ◽  
Cosmic Ray ◽  
Starburst Galaxies ◽  
Spectral Energy ◽  
Minor Role ◽  
Molecular Gas ◽  
Line Energy

We present the detection of multiple carbon monoxide CO line transitions with ALMA in a few tens of infrared-selected galaxies on and above the main sequence at z = 1.1−1.7. We reliably detected the emission of CO (5 − 4), CO (2 − 1), and CO (7 − 6)+[C I](3P2  −  3P1) in 50, 33, and 13 galaxies, respectively, and we complemented this information with available CO (4 − 3) and [C I](3P1  −  3P0) fluxes for part of the sample, and by modeling of the optical-to-millimeter spectral energy distribution. We retrieve a quasi-linear relation between LIR and CO (5 − 4) or CO (7 − 6) for main-sequence galaxies and starbursts, corroborating the hypothesis that these transitions can be used as star formation rate (SFR) tracers. We find the CO excitation to steadily increase as a function of the star formation efficiency, the mean intensity of the radiation field warming the dust (⟨U⟩), the surface density of SFR (ΣSFR), and, less distinctly, with the distance from the main sequence (ΔMS). This adds to the tentative evidence for higher excitation of the CO+[C I] spectral line energy distribution (SLED) of starburst galaxies relative to that for main-sequence objects, where the dust opacities play a minor role in shaping the high-J CO transitions in our sample. However, the distinction between the average SLED of upper main-sequence and starburst galaxies is blurred, driven by a wide variety of intrinsic shapes. Large velocity gradient radiative transfer modeling demonstrates the existence of a highly excited component that elevates the CO SLED of high-redshift main-sequence and starbursting galaxies above the typical values observed in the disk of the Milky Way. This excited component is dense and it encloses ∼50% of the total molecular gas mass in main-sequence objects. We interpret the observed trends involving the CO excitation as to be mainly determined by a combination of large SFRs and compact sizes, as a large ΣSFR is naturally connected with enhanced dense molecular gas fractions and higher dust and gas temperatures, due to increasing ultraviolet radiation fields, cosmic ray rates, as well as dust and gas coupling. We release the full data compilation and the ancillary information to the community.

scholarly journals Gamma-ray astrophysics in the MeV range

2021 ◽  
Author(s):  
Alessandro De Angelis ◽  
Vincent Tatischeff ◽  
Andrea Argan ◽  
Søren Brandt ◽  
Andrea Bulgarelli ◽  
...  
Keyword(s):  
High Efficiency ◽  
Gamma Ray ◽  
Earth Science ◽  
Technological Development ◽  
Cosmic Ray ◽  
Space Mission ◽  
Compact Objects ◽  
Medium Size ◽  
Cosmic Ray Interactions ◽  
Silicon Microstrip Detectors

AbstractThe energy range between about 100 keV and 1 GeV is of interest for a vast class of astrophysical topics. In particular, (1) it is the missing ingredient for understanding extreme processes in the multi-messenger era; (2) it allows localizing cosmic-ray interactions with background material and radiation in the Universe, and spotting the reprocessing of these particles; (3) last but not least, gamma-ray emission lines trace the formation of elements in the Galaxy and beyond. In addition, studying the still largely unexplored MeV domain of astronomy would provide for a rich observatory science, including the study of compact objects, solar- and Earth-science, as well as fundamental physics. The technological development of silicon microstrip detectors makes it possible now to detect MeV photons in space with high efficiency and low background. During the last decade, a concept of detector (“ASTROGAM”) has been proposed to fulfil these goals, based on a silicon hodoscope, a 3D position-sensitive calorimeter, and an anticoincidence detector. In this paper we stress the importance of a medium size (M-class) space mission, dubbed “ASTROMEV”, to fulfil these objectives.

scholarly journals High energy cosmic ray interactions and UHECR composition problem

2019 ◽  
Vol 210 ◽  
pp. 02001
Author(s):  
Sergey Ostapchenko
Keyword(s):  
Experimental Data ◽  
Monte Carlo ◽  
Cosmic Rays ◽  
Cosmic Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
Hadronic Interactions ◽  
High Energy Cosmic Rays ◽  
Cosmic Ray Interactions ◽  
Composition Problem

The differences between contemporary Monte Carlo generators of high energy hadronic interactions are discussed and their impact on the interpretation of experimental data on ultra-high energy cosmic rays (UHECRs) is studied. Key directions for further model improvements are outlined. The prospect for a coherent interpretation of the data in terms of the UHECR composition is investigated.

Cosmic-Ray Interactions at1011-1013eV

1971 ◽  
Vol 4 (1) ◽  
pp. 37-45 ◽  
Author(s):  
E. W. Cowan ◽  
K. Matthews
Keyword(s):  
Cosmic Ray ◽  
Cosmic Ray Interactions
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