2014A&A...566A..13P


C.D.S. - SIMBAD4 rel 1.7 - 2020.07.13CEST07:02:58

2014A&A...566A..13P - Astronomy and Astrophysics, volume 566A, 13-13 (2014/6-1)

Local ISM 3D distribution and soft X-ray background. Inferences on nearby hot gas and the North Polar Spur.

PUSPITARINI L., LALLEMENT R., VERGELY J.-L. and SNOWDEN S.L.

Abstract (from CDS):

Three-dimensional (3D) interstellar medium (ISM) maps can be used to locate not only interstellar (IS) clouds, but also IS bubbles between the clouds that are blown by stellar winds and supernovae, and that are filled by hot gas. To demonstrate this and to derive a clearer picture of the local ISM, we compare our recent 3D maps of the IS dust distribution to the ROSAT diffuse X-ray background maps after removing heliospheric emission. In the Galactic plane, there is a good correspondence between the locations and extents of the mapped nearby cavities and the soft (0.25keV) background emission distribution, showing that most of these nearby cavities contribute to this soft X-ray emission. Assuming a constant dust-to-gas ratio and homogeneous 106K hot gas filling the cavities, we modeled the 0.25keV surface brightness in a simple way along the Galactic plane as seen from the Sun, taking the absorption by the mapped clouds into account. The data-model comparison favors the existence of hot gas in the solar neighborhood, the so-called Local Bubble (LB). The inferred average mean pressure in the local cavities is found to be on the order of 10000cm–3K, in agreement with previous studies, providing a validation test for the method. On the other hand, the model overestimates the emission from the huge cavities located in the third quadrant. Using CaII absorption data, we show that the dust-to-CaII ratio is very low in this region, implying there is a large quantity of lower temperature (non-X-ray emitting) ionized gas and, as a consequence, a reduction in the volume filled by hot gas, explaining at least part of the discrepancy. In the meridian plane, the main two brightness enhancements coincide well with the LB's most elongated parts and chimneys connecting the LB to the halo, but no particular nearby cavity is found towards the enhancement in the direction of the bright North Polar Spur (NPS) at high latitude. We searched in the 3D maps for the source regions of the higher energy (0.75keV) enhancements in the fourth and first quadrants. Tunnels and cavities are found to coincide with the main bright areas; however, no tunnel or cavity is found to match the low-latitude b>8°, brightest part of the NPS. In addition, the comparison between the 3D maps and published spectral data do not favor the nearby cavities being located within ∼200pc as potential source regions for the NPS. Those examples illustrate the potential use of more detailed 3D distributions of the nearby ISM for interpreting the diffuse soft X-ray background.

Abstract Copyright:

Journal keyword(s): ISM: bubbles - ISM: structure - X-rays: diffuse background - local insterstellar matter - solar neighborhood - ISM: general

Simbad objects: 22

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Number of rows : 22

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2020
#notes
1 NAME Cas Cloud ~ 00 37 +65.8           ~ 25 0
2 NAME Perseus Cloud SFR 03 35.0 +31 13           ~ 1061 0
3 * bet CMa bC* 06 22 41.9853527 -17 57 21.307352 0.77 1.73 1.97 2.11 2.35 B1II-III 682 0
4 NAME Vela Supershell sh 07 40 -22.           ~ 24 0
5 NAME North Polar Spur ISM 12 00 +00.0           ~ 301 1
6 NAME Musca Cld 12 23 -71.3           ~ 156 0
7 NAME NGP reg 12 51 26.275 +27 07 41.70           ~ 1020 0
8 NAME Loop I SR? 15 01 -38.7           ~ 328 2
9 NAME Circinus Cloud Cld 15 02 -63.0           ~ 31 0
10 NAME Lup Cloud SFR 16 03 -38.1           ~ 517 0
11 NAME ASSOC II SCO As* 16 15 -24.2           ~ 1120 1
12 NAME Sco-Oph Cloud ~ 16 30 00 -21 30.0           ~ 15 0
13 NAME Fermi Bubbles bub 17 45 -29.0           ~ 271 0
14 NAME Gal Center reg 17 45 40.04 -29 00 28.1           ~ 11542 0
15 NAME Serpens Cloud SFR 18 29 49 +01 14.8           ~ 912 2
16 NAME Aql Rift DNe 18 32 -01.0           ~ 234 1
17 NAME Northern Coalsack DNe 20 21 +37.0           ~ 102 0
18 NAME Cep Cloud SFR 22 00.0 +76 30           ~ 99 0
19 NAME Gould Belt PoG ~ ~           ~ 711 1
20 NAME Local Bubble ISM ~ ~           ~ 693 0
21 NAME Vela Field reg ~ ~           ~ 149 0
22 NAME Aql Region reg ~ ~           ~ 304 0

    Equat.    Gal    SGal    Ecl

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2020.07.13-07:02:58

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