The halo of the Milky Way provides a laboratory to study the properties of the shocked hot gas that is predicted by models of galaxy formation. There is observational evidence of energy injection ...into the halo from past activity in the nucleus of the Milky Way
; however, the origin of this energy (star formation or supermassive-black-hole activity) is uncertain, and the causal connection between nuclear structures and large-scale features has not been established unequivocally. Here we report soft-X-ray-emitting bubbles that extend approximately 14 kiloparsecs above and below the Galactic centre and include a structure in the southern sky analogous to the North Polar Spur. The sharp boundaries of these bubbles trace collisionless and non-radiative shocks, and corroborate the idea that the bubbles are not a remnant of a local supernova
but part of a vast Galaxy-scale structure closely related to features seen in γ-rays
. Large energy injections from the Galactic centre
are the most likely cause of both the γ-ray and X-ray bubbles. The latter have an estimated energy of around 10
erg, which is sufficient to perturb the structure, energy content and chemical enrichment of the circumgalactic medium of the Milky Way.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We investigate the prospects of the Spectrum-Roentgen-Gamma (SRG) mission in search for the keV-scale mass sterile neutrino dark matter radiatively decaying into active neutrinos and photons. The ...ongoing all-sky x-ray survey of the SRG space observatory with data acquired by the ART-XC and eROSITA telescopes can provide a possibility to fully explore the resonant production mechanism of the dark matter sterile neutrino, which exploits the lepton asymmetry in the primordial plasma consistent with cosmological limits from the big bang nucleosynthesis. In particular, it is shown that at the end of the four year all-sky survey, the sensitivity of the eROSITA telescope near the 3.5 keV line signal reported earlier can be comparable to that of the XMM-Newton with all collected data, which will allow one to carry out another independent study of the possible sterile neutrino decay signal in this area. In the energy range below ≈2.4 keV, the expected constraints on the model parameters can be significantly stronger than those obtained with the XMM-Newton. From the ART-XC data, in the energy range approximately from 5 to 20 keV, it can be possible to get more stringent constraints than those obtained with NuSTAR so far. We conclude that the SRG mission has a very high potential in testing the sterile neutrino dark matter hypothesis.
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CMK, CTK, FMFMET, IJS, NUK, PNG, UM
We present results of the study of persistent high-mass X-ray binaries (HMXBs) in the Milky Way, obtained from the deep INTEGRAL Galactic plane survey. This survey provides us a new insight into the ...population of HMXBs because almost half of the whole sample consists of sources discovered with INTEGRAL. It is demonstrated for the first time that the majority of persistent HMXBs have supergiant companions and their luminosity function steepens somewhere around ∼2 × 1036 erg s−1. We show that the spatial density distribution of HMXBs correlates well with the star formation rate distribution in the Galaxy. The vertical distribution of HMXBs has a scale-height h 85 pc, that is somewhat larger than the distribution of young stars in the Galaxy. We propose a simple toy model, which adequately describes general properties of HMXBs in which neutron stars accrete a matter from the wind of its companion (wind-fed NS-HMXBs population). Using the elaborated model we argue that a flaring activity of the so-called supergiant fast X-ray transients, the recently recognized sub-sample of HMXBs, is likely related with the magnetic arrest of their accretion.
We present the results of our study of the X-ray emission from the Ophiuchus galaxy cluster based on INTEGRAL/IBIS data in the energy range 20–120 keV. Our goal is the search for a nonthermal ...emission component from the cluster. Using the INTEGRAL data over the period of observations 2003–2009, we have constructed the images of the Ophiuchus galaxy cluster in different energy bands from 20 to 120 keV with the extraction of spectral information. We show that in the hard X-ray energy band the source is an extended one with an angular size of
. Assuming a fixed intracluster gas temperature of 8.5 keV, a power-law component of the possible nonthermal X-ray emission is observed at a 5.5
significance level, the flux from which is consistent with previous studies. However, in view of the uncertainty in constraining the thermal emission component in the X-ray spectrum at energies above 20 keV, we cannot make the assertion about a significant detection of nonthermal emission from the cluster. Based on the fact of a confident detection of the cluster up to 70 keV, we can draw the conclusion only about the possible presence of a nonthermal excess at energies above 60 keV.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
We report the results of an analysis of data obtained with the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), Swift and Rossi X-ray Timing Explorer (RXTE) observatories during the 2010 ...April and September outbursts of the X-ray pulsar RX J0440.9+4431. The temporal and spectral properties of the pulsar in a wide energy band (0.6-120 keV) were studied for the first time. We discovered a ∼32-keV cyclotron resonant scattering feature in the source spectrum that allowed us to estimate the magnetic field strength of the neutron star as B≃ 3.2 × 1012 G. The estimate of the magnetic field strength was confirmed by a comprehensive analysis of the noise power spectrum of the source. Based on the recurrence time between Type I outbursts, the orbital period of the binary system can be estimated as ∼155 d. We have shown that the pulse profile has a sinusoidal-like single-peaked shape and has practically no dependence on the source luminosity or energy band.
PROPELLER EFFECT IN THE TRANSIENT X-RAY PULSAR SMC X-2 Lutovinov, Alexander A.; Tsygankov, Sergey S.; Krivonos, Roman A. ...
Astrophysical journal/The Astrophysical journal,
01/2017, Volume:
834, Issue:
2
Journal Article
Peer reviewed
Open access
ABSTRACT We report the results of the monitoring campaign of the transient X-ray pulsar SMC X-2 performed with the Swift/XRT telescope over the period of 2015 September-2016 January during the Type ...II outburst. During this event, the bolometric luminosity of the source ranged from 1039 down to several ×1034 erg s−1. Moreover, we discovered its dramatic drop by a factor of more than 100 below the limiting value of erg s−1, which can be interpreted as a transition to the propeller regime. These measurements make SMC X-2 the sixth pulsating X-ray source where such a transition is observed and allow us to estimate the magnetic field of the neutron star in the system B 3 × 1012 G, which is in agreement with independent results of the spectral analysis.
We have carried out a deep survey of the M81 field in the 25–60 keV energy band based on long-term (2003–2023) INTEGRAL observations. A record sensitivity of 0.16 mCrab at a detection significance of
...has been achieved in the central part of the field owing to the long accumulated exposure (19.2 Ms). The total area of the survey is 1004 deg
at a sensitivity level better than 0.72 mCrab. We have produced a catalog of sources detected at a significance level higher than
. It contains 51 objects most of which are active galactic nuclei (AGNs). The median redshift of the Seyfert galaxies in the catalog is
. Six sources have not been detected previously in any of the X-ray surveys. According to the available indirect data, all of them and two more sources that have already been entered previously into the INTEGRAL survey catalogs can also be AGNs, including those with strong internal absorption.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
8.
Central Part of the Galaxy in X-Rays Krivonos, R. A.
Bulletin of the Russian Academy of Sciences. Physics,
08/2019, Volume:
83, Issue:
8
Journal Article
Peer reviewed
Studying the central part of the Galaxy is of great interest for observational astronomy and astrophysics. Based on the results from observations in the X-ray energy range, remnants of supernova ...explosions, star clusters, X-ray binaries, and nonthermal filaments have been detected in a small region of the Galactic center. However, the most interesting object of study is the supermassive black hole Sagittarius A*, along with its immediate environment, including the recently discovered extended emission (several parsecs) and nearby molecular clouds. This work presents the preliminary results from a study of the properties of the stellar population in the immediate environment of Sagittarius A*. Using data from the NuSTAR orbital X-ray telescope and the stellar mass population model of the central part of the Galaxy, we estimate the X-ray luminosity per unit stellar mass of the Sagittarius A* extended emission, which is found to be a factor several times higher than the similar value throughout the Galaxy.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Molecular gas in the Arches cloud located near the Arches cluster is one of the emitters of the K- line of neutral iron and the X-ray continuum in the Galactic center (GC). Similarly to the cloud Sgr ...B2, another well-known emitter of the iron line in the GC, the Arches cloud demonstrates a temporal decline of the X-ray emission. The most natural origin of this emission is irradiation of primary photons of an X-ray flare from a distant source, most likely Sgr A*. However, recent observations of the Arches cloud discovered variations of equivalent width of the 6.4 keV iron line, which indicated that the X-ray emission from the cloud is a combination of two components with different origins and different equivalent widths, one of which is time variable, while the other is stationary during the period of observations. We considered two different scenarios: (a) this emission is formed by reflection from two clouds, which are at some distance from each other, when they are irradiated by two different flares; and (b) the other scenario assumes a combination of X-ray fluxes produced in the same cloud by reflection of primary photons and by subrelativistic cosmic rays. We present restrictions for both the model and conditions at which these scenarios can be realized. Although none of the models can be completely ruled out, we find that the X-ray reflection model requires fewer assumptions and therefore is the most viable.
Using long-term INTEGRAL hard X-ray observations, we have put upper limits on the bolometric luminosity (
erg s
) of the nuclei of 72 nearby dwarf galaxies located in the M81 field. This has allowed ...us to constrain the fraction of galaxies in which the central black hole accretes matter at a rate above 0.1
of the critical one. Under simple assumptions about the distributions of black hole masses and accretion rates this fraction does not exceed 9
. Reliable estimates of the central black hole masses are required to obtain more stringent constraints on the fraction of AGNs.
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DOBA, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, IZUM, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBJE, SBMB, SIK, UILJ, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
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