Soft X-rays from the Large Magellanic Cloud - Implications on the origin of the diffuse X-ray background

1976 ◽  
Vol 206 ◽  
pp. 411 ◽  
Author(s):  
K. S. Long ◽  
G. P. Garmire ◽  
P. C. Agrawal
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
X Rays ◽  
X Ray ◽  
X Ray Background

X-rays from superbubbles in the Large Magellanic Cloud

1991 ◽  
Vol 148 ◽  
pp. 99-100
Author(s):  
You-Hua Chu ◽  
Mordecai-Mark Mac Low
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Shell Structures ◽  
X Rays ◽  
Simple Ring ◽  
X Ray ◽  
Order Of Magnitude

We find diffuse X-ray emission not associated with known SNRs in seven LMC HII complexes. All, except 30 Dor, have simple ring morphologies, indicating shell structures. Assuming these are superbubbles, we find the X-ray luminosity expected from their hot interiors to be an order of magnitude lower than the observed value. SNRs close to the center of a superbubble add very little emission, but we calculate that off-center SNRs hitting the ionized shell could explain the observed emission.

scholarly journals Supersoft X-ray nebulae in the Large Magellanic Cloud

2020 ◽  
Vol 497 (3) ◽  
pp. 3234-3250 ◽  
Author(s):  
Diego A Farias ◽  
Alejandro Clocchiatti ◽  
Tyrone E Woods ◽  
Armin Rest
Keyword(s):  
Interstellar Medium ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
The Other ◽  
X Rays ◽  
X Ray ◽  
Upper Limits ◽  
Type Ia ◽  
Source Models ◽  
Flux Measurements

ABSTRACT Supersoft X-rays sources (SSSs) have been proposed as potential Type Ia supernova (SN Ia) progenitors. If such objects are indeed persistently X-ray luminous and embedded in sufficiently dense interstellar medium (ISM), they will be surrounded by extended nebular emission. These nebulae should persist even long after an SN Ia explosion, due to the long recombination and cooling times involved. With this in mind, we searched for nebular [O iii] emission around four SSSs and three SNRs in the Large Magellanic Cloud, using the 6.5-m Baade telescope at Las Campanas Observatory and the imacs camera. We confirm that, out of the four SSS candidates, only CAL 83 can be associated with an [O iii] nebula. The [O iii] luminosity for the other objects is constrained to ≲17 per cent of that of CAL 83 at 6.8 pc from the central source. Models computed with the photoionization code cloudy indicate that either the ISM densities in the environments of CAL 87, RX J0550.0-7151, and RX J0513.9-6951 must be significantly lower than surrounding CAL 83 or the average X-ray luminosities of these sources over the last ≲10  000 yr must be significantly lower than presently observed, in order to be consistent with the observed luminosity upper limits. For the three SNRs we consider (all with ages <1000 yr), our [O iii] flux measurements together with the known surrounding ISM densities strongly constrain the ionizing luminosity of their progenitors in the last several thousand years, independent of the progenitor channel.

X-Rays from Superbubbles in the Large Magellanic Cloud. III. X-Ray--dim Superbubbles

1995 ◽  
Vol 450 ◽  
pp. 157 ◽  
Author(s):  
You-Hua Chu ◽  
Hsiao-Wei Chang ◽  
Yu-Ling Su ◽  
Mordecai-Mark Mac Low
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
X Rays ◽  
X Ray

scholarly journals Luminous Supersoft X-ray Sources

1996 ◽  
Vol 165 ◽  
pp. 415-424
Author(s):  
S. Rappaport ◽  
R. Di Stefano
Keyword(s):  
Accretion Disks ◽  
Large Magellanic Cloud ◽  
High Energy ◽  
Magellanic Cloud ◽  
Emission Lines ◽  
Time Variability ◽  
X Rays ◽  
X Ray ◽  
Significant Time ◽  
Einstein Observatory

Supersoft X-ray sources exhibit spectra that are remarkably steep, in that the ratio of low-to-high energy X rays is much larger than is characteristic of the spectra associated with the previously known classes of luminous X-ray sources. The first supersoft sources were discovered during a survey of the Large Magellanic Cloud with the EINSTEIN Observatory (Longet al.1981). The all-sky X-ray survey carried out with ROSAT has now established that luminous supersoft X-ray sources constitute a distinct astronomical class (see, e.g., Hasinger 1994). A number of the identified optical counterparts of the supersoft X-ray sources exhibit blue continua with emission lines of H and He II (Smaleet al.1988; Pakullet al.1988; Cowleyet al.1990), which are characteristic of accretion disks. The X-ray emission of some sources is steady, while others exhibit significant time variability. Table 1 briefly summarizes what is known thus far about the numbers and characteristics of supersoft X-ray sources (see Hasinger 1994, and references therein).

scholarly journals The X-ray Properties of Supernova Remnants in the Large Magellanic Cloud

1983 ◽  
Vol 101 ◽  
pp. 525-533
Author(s):  
Knox S. Long
Keyword(s):  
Supernova Remnants ◽  
Energy Content ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
X Rays ◽  
Free Expansion ◽  
X Ray ◽  
Balmer Lines ◽  
Thermal Energy Content ◽  
Einstein Observatory

There are at least 25 supernova remnants (SNR) in the Large Magellanic Cloud (LMC) with X-ray luminosities exceeding 2 × 1035 erg s−1. As many as 25 other SNR may be contained in the X-ray survey conducted with the Einstein Observatory of the LMC. The X-ray spectra of the 6 SNR observed with the Solid State Spectrometer (SSS) resemble their galactic counterparts; two SNR, N157B and 0540–69.3, may emit X-rays primarily by synchrotron radiation. The density of the medium in which SNR are expanding inferred from the X-ray data appears to decrease with SNR diameter; the density of the ISM inferred from the Balmer lines of 4 new SNR in the LMC is much lower than that inferred from X-ray observations. The apparent thermal energy content of LMC SNR evolves with diameter, peaking at ∼5 × 1050 ergs. The ratio of the densities of the X-ray and [SII] emitting plasmas is consistent with their being in pressure equilibrium. The SN rate in the LMC is ∼1 per 100–200 years. This is the number of SN expected from other considerations. The number diameter relation of LMC SNR is consistent with free expansion. The X-ray data are difficult to understand in terms of traditional Sedov models on SNR evolution; probably ejecta and multiphase ISM are required to explain the X-ray properties of LMC SNR.

scholarly journals 106-107 K Gas in the Magellanic Clouds

1999 ◽  
Vol 190 ◽  
pp. 32-36 ◽  
Author(s):  
S. L. Snowden
Keyword(s):  
Emission Measure ◽  
Neutral Hydrogen ◽  
Leading Edge ◽  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
Total Flux ◽  
Color Temperature ◽  
X Rays ◽  
Space Density ◽  
X Ray

The Large Magellanic Cloud contains an extensive distribution of hot plasma and is one of the brightest extragalactic regions in the diffuse 0.5–2.0 keV X-ray sky. The plasma is not isothermal but increases in color temperature from west to east from ~106.6 K to ~106.9 K. The total flux from this plasma is ~ 1038 ergs s−1. The average emission measure is ~ 0.014 cm−6 pc, which if the emitting plasma is distributed uniformly throughout the LMC, implies a space density of ne ~ 0.002 cm−3. There is an apparent ¼ keV enhancement in the southwest of the LMC, which if associated with the LMC implies a considerable emission measure of ~ 106 K plasma. (The foreground column density of Galactic neutral hydrogen is ~ 6 × 1020 cm−2, or several optical depths for ¼ keV emission.)The Small Magellanic Cloud exhibits less diffuse X-ray emission in the 0.5–2.0 keV band than the LMC with a total flux of ~ 4 × 1036 ergs s−1. The average emission measure of ~ 0.006 cm−6 pc also implies a space density of ne ~ 0.002 cm−3. The optical depth of Galactic HI for ¼ keV X-rays from the SMC is considerably lower than that for the LMC. However, while there is a significant variation in the ¼ keV band intensity over the SMC field, it is in general not particularly well correlated with anything associated with the SMC, although there is an enhancement which may be related to the leading edge of the SMC. Considerably more work is needed to unravel the origin of the structure, which may be associated instead with either emission or absorption variations in either the disk or halo of the Milky Way.

scholarly journals Deep hard X-ray survey of the Large Magellanic Cloud

2012 ◽  
Vol 428 (1) ◽  
pp. 50-57 ◽  
Author(s):  
S. A. Grebenev ◽  
A. A. Lutovinov ◽  
S. S. Tsygankov ◽  
I. A. Mereminskiy
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
X Ray

scholarly journals 1/4 Ke V Diffuse Background and the Local Interstellar Medium

1989 ◽  
Vol 120 ◽  
pp. 536-536
Author(s):  
S.L. Snowden
Keyword(s):  
Interstellar Medium ◽  
Filling Factor ◽  
Thermal Emission ◽  
Mean Free Path ◽  
Physical Parameters ◽  
X Rays ◽  
Local Interstellar Medium ◽  
X Ray ◽  
Diffuse Background ◽  
X Ray Background

The 1/4 keV diffuse X-ray background (SXRB) is discussed in relation to the local interstellar medium (LISM). The most likely source for these soft X-rays is thermal emission from a hot diffuse plasma. The existence of a non-zero flux from all directions and the short ISM mean free path of these X-rays (1020HI cm-2), coupled with ISM pressure constraints, imply that the plasma has a local component and that it must, at least locally (nearest hundred parsecs), have a large filling factor. Our understanding of the geometry and physical parameters of the LISM is therefore directly tied to our understanding of the SXRB.

A Soft X-Ray Study of the Large Magellanic Cloud

1981 ◽  
pp. 141-141
Author(s):  
David J. Helfand ◽  
Knox S. Long
Keyword(s):  
Large Magellanic Cloud ◽  
Magellanic Cloud ◽  
X Ray
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