2019A&A...630A..72P


Query : 2019A&A...630A..72P

2019A&A...630A..72P - Astronomy and Astrophysics, volume 630A, 72-72 (2019/10-1)

Non-thermal emission from cosmic rays accelerated in H II regions.

PADOVANI M., MARCOWITH A., SANCHEZ-MONGE A., MENG F. and SCHILKE P.

Abstract (from CDS):


Context. Radio observations at metre-centimetre wavelengths shed light on the nature of the emission of HII regions. Usually this category of objects is dominated by thermal radiation produced by ionised hydrogen, namely protons and electrons. However, a number of observational studies have revealed the existence of HII regions with a mixture of thermal and non-thermal radiation. The latter represents a clue as to the presence of relativistic electrons. However, neither the interstellar cosmic-ray electron flux nor the flux of secondary electrons, produced by primary cosmic rays through ionisation processes, is high enough to explain the observed flux densities.
Aims. We investigate the possibility of accelerating local thermal electrons up to relativistic energies in HII region shocks.
Methods. We assumed that relativistic electrons can be accelerated through the first-order Fermi acceleration mechanism and we estimated the emerging electron fluxes, the corresponding flux densities, and the spectral indexes.
Results. We find flux densities of the same order of magnitude of those observed. In particular, we applied our model to the "deep south" (DS) region of Sagittarius B2 and we succeeded in reproducing the observed flux densities with an accuracy of less than 20% as well as the spectral indexes. The model also gives constraints on magnetic field strength (0.3-4mG), density (1-9x104cm–3), and flow velocity in the shock reference frame (33-50km/s) expected in DS.
Conclusions. We suggest a mechanism able to accelerate thermal electrons inside HII regions through the first-order Fermi acceleration. The existence of a local source of relativistic electrons can explain the origin of both the observed non-thermal emission and the corresponding spectral indexes.

Abstract Copyright: © ESO 2019

Journal keyword(s): stars: formation - H II regions - radio continuum: ISM - cosmic rays - acceleration of particles

Simbad objects: 1

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Number of rows : 1
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2023
#notes
1 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2150 1

Query : 2019A&A...630A..72P

Basic data :
NAME Sgr B2 -- Molecular Cloud
Origin of the objects types :

(Ref) Object type as listed in the reference "Ref"
(acronym) Object type linked to the acronym according to the original reference
() Anterior to 2007, before we can link the objet type to a reference, or given by the CDS team in some particular cases

Other object types:
MoC (), SFR (2016MNRAS), X ([SKM2002])
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
ICRS coord. (ep=J2000) :
17 47 20.4 -28 23 07 [ ] D ~
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
FK4 coord. (ep=B1950 eq=1950) :
17 44 10.6 -28 22 05 [ ]
Syntax of coordinates is : "ra dec (wtype) [error ellipse] quality bibcode" :
  • ra dec : right ascension and declination (unit and frame defined according to your Output Options)
    Grey values are increasing the original precision due to the computation of frame transformations
  • (wtype) : wavelength class for the origin of the coordinates (Rad, mm, IR, Optical, UV, Xray, Gam)
  • [error ellipse] : measurement uncertainty, on (ra,dec) if the positional angle is 90 degrees, on (majaxis,minaxis) otherwise (in mas at defined epoch in the original catalogue),
    position angle (in degrees North celestial pole to East)
  • quality : flag of quality
    • E ≥ 10"
    • D : 1-10" (and some old data)
    • C : 0.1-1"
    • B : 0.01-0.1" + 2MASS, Tyc
    • A : VLBI, Hipparcos
  • bibcode : bibcode of the coordinates reference
Gal coord. (ep=J2000) :
000.6667 -00.0362 [ ]
Syntax of radial velocity (or/and redshift) is : "value [error] (wavelength) quality bibcode"
  • value : radial velocity or/and redshift (Heliocentric frame) according to your Output Options
    (redshift may be not displayed if the data value is <0 and the database inside value is a radial velocity)
  • [error] : error of the corresponding value displayed before
  • (wavelength) : wavelength range of the measurement : Rad, mm, IR, Opt, UV, Xray, Gam or  '∼'(unknown)
  • quality : flag of quality ( A=best quality -> E=worst quality, {� } =unknown quality)
  • bibcode : bibcode of the value's origin
Radial velocity / Redshift / cz :
V(km/s) 61.6 [~] / z(~) 0.000205 [~] / cz 61.61 [~]
   D 1973ApJ...181..781F
SIMBAD within arcmin
', {sourceSize:12, color:'#30a090'})); aladin.on('objectClicked', function(object) { var objName=object.data.MAIN_ID; aladin.showPopup(object.ra,object.dec,'',''+ objName+''); });" title="Show Simbad objects"> Overlay Simbad points in this preview
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notes:

  • also GMC


Hierarchy : number of linked objects
whatever the membership probability is (see description here ) :

: 1 : 1 Display criteria :

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NAME Sagittarius B2 NAME Sgr B2 [SKM2002] G000.7+1

References (2150 between 1850 and 2023) (Total 2150)
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herschel : 45    ISO : 73   

   


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2023.02.08-02:18:55

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