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Table 2

Thermodynamic parameters (interstellar phase, temperature, mean hydrogen density and hydrogen mass) of the different structural components in our representation of the interstellar gas.

Component Phase T [K]a nH    [cm-3 b MH    [M c

Central cavity (CC)
 Extended component warm ionized 7000 910 190
 Minispiral warm ionized 7000 6200 12
 Neutral streamers atomic 170 1.5 × 104 160
 Central sphere hot ionized 1.5 × 107 18.5 0.12

Circumnuclear ring (CNR)
 Main molecular ring molecular 150 4.4 × 105 2 × 105
 Photo-dissociated inner layer atomic 300 3.2 × 104 1300

Sgr A East SNR
 Extended component hot ionized 1.5 × 107 3.0 19

Radio halo
 Extended component warm ionized 7000 210 1.3 × 104

Belt of molecular cloudsde
 M−0.13−0.08 (SC) molecular 60 2 × 104 2.2 × 105
 M−0.02−0.07 (EC) molecular 60 1.9 × 105
  Preshock core 2 × 104 1.5 × 105
  Swept-up shell 3 × 104 3.8 × 104
 Molecular ridge (MR) molecular 60 3 × 104 (5.9−7.3) × 104
  Swept-up shell 3.8 × 104
  Bridge (2.1−3.5) × 104
 Southern streamer (SS) molecular 60 3 × 104 (1.6−3.2) × 104
 Western streamer (WS) molecular 60 3 × 104 4.5 × 103
 Northern ridge (NR) molecular 60 3 × 104 2.2 × 103

Notes. 

(a)

The actual temperature ranges, accounting for observational uncertainties, model approximations and true physical dispersion, are [in K]: central cavity:  ≈ (5000−13 000) for the warm ionized gas;  ≈(100−240) for the atomic gas;  ≈ (1.4−2.3) × 107 for the hot ionized gas. CNR:  ≈ (40−300) for the molecular gas;  ≈(200−1000) for the atomic gas. Sgr A East:  ≈(1−7) × 107. Radio halo:  ≈ (5000−10 000). Belt of molecular clouds:  ≈ (15−200).

(b)

The actual hydrogen density ranges, accounting for observational uncertainties, model approximations and true physical dispersion, are [in cm-3]: central cavity:  ≈ (103 − 2 × 105) for the warm ionized gas;  ≈ (2 × 103−3 × 105) for the atomic gas;  ≈ (10−40) for the hot ionized gas. CNR:  ≈ (104−2 × 108) for the molecular gas;  ≈ (104−2 × 105) for the atomic gas. Sgr A East:  ≈ (1.5−30). Radio halo:  ≈ (10−1000). Belt of molecular clouds:  ≈ (104−4 × 106).

(c)

The errors in our adopted masses are estimated as follows: a factor  ~4 for the ionized components (including uncertainties in the observed emission measures, in the projected surface areas and in the line-of-sight depths); a factor  ~5 for the atomic and molecular components (including uncertainties in the measured column densities, in the tracer-to-hydrogen ratios and in the projected surface areas). For the radio halo, the error is in fact larger than a factor  ~4, as the relative contribution from warm ionized gas to the observed radio emission is itself very uncertain.

(d)

The swept-up shell is indicated twice, because it is part of both M − 0.02 − 0.07 and the molecular ridge.

(e)

The mass ranges given for the Bridge (and hence the molecular ridge) and the southern streamer correspond to the range in the line-of-sight coordinate of the center of M − 0.13-0.08, xSC = (4−12) pc.

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