2002A&A...389..252C


Query : 2002A&A...389..252C

2002A&A...389..252C - Astronomy and Astrophysics, volume 389, 252-270 (2002/7-1)

Interstellar gas in the Galaxy and the X-ray luminosity of Sgr A* in the recent past.

CRAMPHORN C.K. and SUNYAEV R.A.

Abstract (from CDS):

Information about the X-ray luminosity of the supermassive black hole located at the Galactic center (GC), Sgr A*, and its temporal variations in the past is imprinted in the scattered emission observed today in the direction towards giant molecular clouds (GMCs) located in our Galaxy. Due to light travel time effects these clouds probe the activity of Sgr A* at different times in the past depending on their position relative to the GC and the observer. In this paper we combine results of recent ASCA observations along the Galactic plane, providing upper limits for the scattered flux in the 4-10keV range produced in a given direction, with data from CO surveys of the same regions. These CO surveys map the position and mass of the molecular gas which the GMCs are made up of. Demanding the scattered flux to be not larger than the observed one, this data enables us to derive upper limits for the 4-10keV luminosity of Sgr A* at certain times during the last 40000 years down to about 8x1040erg/s. At other times the limits are less tight, of the order of 1041-1042erg/s. For two periods of time of about 2000 and 4000 years duration 8000 and 14000 years ago the currently available CO data is insensitive to any enhanced activity of the GC. Flares lasting longer than 3000 years fill these time gaps and therefore can be excluded to have occurred during the last 40000 years with a luminosity larger than a few 1042erg/s. The more extended and continuous HI distribution in the Galactic disk, which also scatters the radiation emitted by Sgr A*, allows us to extend the time coverage further into the past, back to about 110000 years, albeit the limits are becoming less tight. We thereby can rule out a long term X-ray activity phase of Sgr A* at one per cent of its Eddington level ending less than about 80000 years ago. The limits presented in this paper can be improved by observations of emission in the fluorescent iron Kα-line. We study the feasibility of these methods to investigate past nuclear activity in other spiral galaxies observed with the angular resolution of X-ray telescopes like Chandra and XMM-Newton.

Abstract Copyright:

Journal keyword(s): black hole physics - scattering - galaxy: center - galaxies: active - X-rays: ISM - X-rays: galaxies

Simbad objects: 29

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Number of rows : 29
N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
#notes
1 M 31 G 00 42 44.330 +41 16 07.50 4.86 4.36 3.44     ~ 11836 1
2 M 77 GiP 02 42 40.7091669408 -00 00 47.859690204 9.70 9.61 8.87 10.1 9.9 ~ 4335 2
3 NGC 4151 Sy1 12 10 32.5759813872 +39 24 21.063527532   12.18 11.48     ~ 3526 2
4 M 100 AGN 12 22 54.9299993592 +15 49 20.296257960 10.04 10.05 9.35     ~ 1743 2
5 M 101 GiP 14 03 12.583 +54 20 55.50   8.46 7.86 7.76   ~ 2711 2
6 NAME Sgr C MoC 17 44 36.3 -29 28 13           ~ 338 0
7 NAME Galactic Center reg 17 45 39.60213 -29 00 22.0000           ~ 12985 0
8 NAME Sgr A* X 17 45 40.03599 -29 00 28.1699           ~ 3890 3
9 NAME Sgr B2 MoC 17 47 20.4 -28 23 07           ~ 2101 1
10 SRBY 3 MoC 18 04.2 -21 46           ~ 4 0
11 SRBY 14 MoC 18 07.9 -20 19           ~ 4 0
12 SRBY 59 MoC 18 22.9 -14 03           ~ 3 0
13 SRBY 80 MoC 18 28.6 -10 47           ~ 4 0
14 SRBY 89 MoC 18 30.7 -09 35           ~ 4 0
15 SRBY 85 MoC 18 30.8 -09 56           ~ 4 0
16 SRBY 116 MoC 18 36.7 -07 29           ~ 5 0
17 SRBY 122 MoC 18 38.5 -06 31           ~ 4 0
18 SRBY 128 MoC 18 39.1 -06 19           ~ 5 0
19 SRBY 151 MoC 18 43.3 -04 10           ~ 4 0
20 SRBY 152 MoC 18 43.3 -03 50           ~ 5 0
21 SRBY 158 MoC 18 44.1 -03 29           ~ 4 0
22 SRBY 162 Mas 18 46 03.6 -02 39 26           ~ 31 1
23 SNR G030.8-00.0 SNR 18 47 32 -01 56.5           ~ 483 0
24 SRBY 191 MoC 18 52.8 +00 54           ~ 4 0
25 SRBY 193 MoC 18 53.5 +01 13           ~ 4 0
26 SRBY 201 MoC 18 55.9 +01 58           ~ 3 0
27 SRBY 206 MoC 18 58.1 +03 02           ~ 4 0
28 SRBY 214 MoC 19 04.8 +06 04           ~ 4 0
29 SRBY 217 MoC 19 07.2 +07 13           ~ 4 0

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2022.06.30-18:54:23

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