arXiv subjects

Tomonori Totani

Publications and source records attributed to Tomonori Totani.

At least 37 records · Page 2Linked to original sources

arXiv2018

A search for optical transients associated with Fast Radio Burst 150418

We have searched for optical variability in the host galaxy of the radio variable source which is possibly associated with fast radio burst (FRB) 150418. We compare images of the galaxy taken 1 day after the burst using Subaru/Suprime-Cam with images taken $\sim$ 1 year after the burst using Gemini-South/GMOS. No optical variability is found between the two epochs with a limiting absolute magnitude $\gtrsim -19$ (AB). This limit applies to optical variability of the putative active galactic nucleus in the galaxy on a timescale of $\sim$ 1 year, and also to the luminosity of an optical counterpart of FRB~150418 one day after the burst should it have occurred in this galaxy.

astro-ph.HE↗

arXiv2018

Lethal radiation from nearby supernovae helps to explain the small cosmological constant

The observed value $Λ_{\rm obs}$ of the cosmological constant $Λ$ is extremely smaller than theoretical expectations, and the anthropic argument has been proposed as a solution to this problem because galaxies do not form when $Λ\gg Λ_{\rm obs}$. However, the contemporary galaxy formation theory predicts that stars form even with a high value of $Λ/ Λ_{\rm obs} \sim$ 50, which makes the anthropic argument less persuasive. Here we calculate the probability distribution of $Λ$ using a model of cosmological galaxy formation, considering extinction of observers caused by radiation from nearby supernovae. The life survival probability decreases in a large $Λ$ universe because of higher stellar density. Using a reasonable rate of lethal supernovae, we find that the mean expectation value of $Λ$ can be close to $Λ_{\rm obs}$, and hence this effect may be essential to understand the small but nonzero value of $Λ$. It is predicted that we are located on the edge of habitable regions about stellar density in the Galaxy, which may be tested by future exoplanet studies.

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arXiv2018

Diffuse x-ray emission from the northern arc of loop I observed with suzaku

After discovery of the Fermi bubbles, giant structures observed in radio to X-rays have been discussed as possi- ble evidence of past activities in the Galactic Center (GC). We report here on the analysis of Suzaku data pointing around the Loop I arc. The diffuse X-ray emission was well represented by the three-component model: (1) an unabsorbed thermal plasma with kT ~ 0.1 keV either from the Local Hot Bubble (LHB) and/or solar wind charge exchange (SWCX), (2) an absorbed thermal plasma regarded as a contribution from the Loop I and the Galactic halo (GH), and (3) an absorbed power-law component representing the cosmic X-ray background. The temper- ature of the absorbed thermal plasma was clustered in a range of 0.30 +- 0.02 keV along Loop I ("ON" regions), whereas the temperature was about 20 % lower in the cavity adjacent to the bubbles and Loop I ("OFF" regions) with 0.24 +- 0.03 keV. The emission measure (EM) varied along the Galactic latitude, and was well correlated with the count rate variation as measured with the ROSAT in 0.75 keV band. Although the amount of neutral gas was not conclusive to constrain on the distance to Loop I, the observed EM values rule out a hypothesis that the structure is close to the Sun; we argue that the Loop I is a distant, kpc structure of the shock-heated GH gas. We discuss the origin of apparent mismatch in the morphologies of the Fermi bubbles and the Loop I arc, suggesting a two-step explosion process in the GC.

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arXiv2018

The Subaru FMOS galaxy redshift survey (FastSound). V. Intrinsic alignments of emission line galaxies at $z\sim 1.4$

Intrinsic alignments (IA), the coherent alignment of intrinsic galaxy orientations, can be a source of a systematic error of weak lensing surveys. The redshift evolution of IA also contains information about the physics of galaxy formation and evolution. This paper presents the first measurement of IA at high redshift, $z\sim 1.4$, using the spectroscopic catalog of blue star-forming galaxies of the FastSound redshift survey, with the galaxy shape information from the Canada-Hawaii-France telescope lensing survey. The IA signal is consistent with zero with power-law amplitudes fitted to the projected correlation functions for density-shape and shape-shape correlation components, $A_{δ+}=-0.0071\pm 0.1340$ and $A_{++}=-0.0505\pm 0.0848$, respectively. These results are consistent with those obtained from blue galaxies at lower redshifts (e.g., $A_{δ+}=0.0035_{-0.0389}^{+0.0387}$ and $A_{++}=0.0045_{-0.0168}^{+0.0166}$ at $z=0.51$ from the WiggleZ survey). The upper limit of the constrained IA amplitude corresponds to a few percent contamination to the weak-lensing shear power spectrum, resulting in systematic uncertainties on the cosmological parameter estimations by $-0.052<Δσ_8<0.039$ and $-0.039<ΔΩ_m<0.030$.

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arXiv2018

X-ray Detectability of Accreting Isolated Black Holes in Our Galaxy

Detectability of isolated black holes (IBHs) without a companion star but emitting X-rays by accretion from dense interstellar medium (ISM) or molecular cloud gas is investigated. We calculate orbits of IBHs in the Galaxy to derive a realistic spatial distribution of IBHs, for various mean values of kick velocity at their birth $\upsilon_{\rm avg}$. X-ray luminosities of these IBHs are then calculated considering various phases of ISM and molecular clouds, for a wide range of the accretion efficiency $λ$ (a ratio of the actual accretion rate to the Bondi rate) that is rather uncertain. It is found that detectable IBHs mostly reside near the Galactic Centre (GC), and hence taking the Galactic structure into account is essential. In the hard X-ray band, where identification of IBHs from other contaminating X-ray sources may be easier, the expected number of IBHs detectable by the past survey by NuSTAR towards GC is at most order unity. However, 30--100 IBHs may be detected by the future survey by FORCE with an optimistic parameter set of $\upsilon_{\rm avg} = 50 \ \mathrm{km\ s^{-1}}$ and $λ= 0.1$, implying that it may be possible to detect IBHs or constrain the model parameters.

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arXiv2018

X-ray and Gamma-ray Observations of the Fermi Bubbles and NPS/Loop I Structures

The Fermi bubbles were possibly created by large injections of energy into the Galactic Center (GC), either by an active galactic nucleus (AGN) or by nuclear starburst more than ~10 Myr ago. However, the origin of the diffuse gamma-ray emission associated with Loop I, a radio continuum loop spanning across 100 deg on the sky, is still being debated. The northern-most part of Loop I, known as the North Polar Spur (NPS), is the brightest arm and is even clearly visible in the ROSAT X-ray sky map. In this paper, we present a comprehensive review on the X-ray observations of the Fermi bubbles and their possible association with the NPS and Loop I structures. Using uniform analysis of archival Suzaku and Swift data, we show that X-ray plasma with kT ~ 0.3 keV and low metal abundance (Z ~ 0.2 Z_solar) is ubiquitous in both the bubbles and Loop I and is naturally interpreted as weakly shock-heated Galactic halo gas. However, the observed asymmetry of the X-ray-emitting gas above and below the GC has still not been resolved; it cannot be fully explained by the inclination of the axis of the Fermi bubbles to the Galactic disk normal. We argue that the NPS and Loop I may be asymmetric remnants of a large explosion that occurred before the event that created the Fermi bubbles, and that the soft gamma-ray emission from Loop I may be due to either pi^0 decay of accelerated protons or electron bremsstrahlung.

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arXiv2018

Repeating and Non-repeating Fast Radio Bursts from Binary Neutron Star Mergers

Most of fast radio bursts (FRB) do not show evidence for repetition, and such non-repeating FRBs may be produced at the time of a merger of binary neutron stars (BNS), provided that the BNS merger rate is close to the high end of the currently possible range. However, the merger environment is polluted by dynamical ejecta, which may prohibit the radio signal to propagate. We examine this by using a general-relativistic simulation of a BNS merger, and show that the ejecta appears about 1 ms after the rotation speed of the merged star becomes the maximum. Therefore there is a time window in which an FRB signal can reach outside, and the short duration of non-repeating FRBs can be explained by screening after ejecta formation. A fraction of BNS mergers may leave a rapidly rotating and stable neutron star, and such objects may be the origin of repeating FRBs like FRB 121102. We show that a merger remnant would appear as a repeating FRB in a time scale of about 1-10 yrs, and expected properties are consistent with the observations of FRB 121102. We construct an FRB rate evolution model including these two populations of repeating and non-repeating FRBs from BNS mergers, and show that the detection rate of repeating FRBs relative to non-repeating ones rapidly increases with improving search sensitivity. This may explain that the only repeating FRB 121102 was discovered by the most sensitive FRB search with Arecibo. Several predictions are made, including appearance of a repeating FRB 1-10 years after a BNS merger that is localized by gravitational wave and subsequent electromagnetic radiation.

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arXiv2018

High-energy gamma-ray and neutrino production in star-forming galaxies across cosmic time: Difficulties in explaining the IceCube data

We present a new theoretical modeling to predict luminosity and spectrum of gamma-ray and neutrino emission of a star-forming galaxy, from star formation rate ($ψ$), gas mass ($M_{\rm gas}$), stellar mass, and disk size, taking into account production, propagation and interactions of cosmic rays. The model reproduces the observed gamma-ray luminosities of nearby galaxies detected by {\it Fermi} better than the simple power-law models as a function of $ψ$ or $ψM_{\rm gas}$. Then this model is used to predict the cosmic background flux of gamma-ray and neutrinos from star-forming galaxies, by using a semi-analytical model of cosmological galaxy formation that reproduces many observed quantities of local and high-redshift galaxies. Calibration of the model using gamma-ray luminosities of nearby galaxies allows us to make a more reliable prediction than previous studies. In our baseline model star-forming galaxies produce about 20% of isotropic gamma-ray background unresolved by {\it Fermi}, and only 0.5% of IceCube neutrinos. Even with an extreme model assuming a hard injection cosmic-ray spectral index of 2.0 for all galaxies, at most 22% of IceCube neutrinos can be accounted for. These results indicate that it is difficult to explain most of IceCube neutrinos by star-forming galaxies, without violating the gamma-ray constraints from nearby galaxies.

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arXiv2017

Gravity with free initial conditions: a solution to the cosmological constant problem testable by CMB B-mode polarization

In standard general relativity the universe cannot be started with arbitrary initial conditions, because four of the ten components of the Einstein's field equations (EFE) are constraints on initial conditions. In the previous work it was proposed to extend the gravity theory to allow free initial conditions, with a motivation to solve the cosmological constant problem. This was done by setting four constraints on metric variations in the action principle, which is reasonable because the gravity's physical degrees of freedom are at most six. However, there are two problems about this theory; the three constraints in addition to the unimodular condition were introduced without clear physical meanings, and the flat Minkowski spacetime is unstable against perturbations. Here a new set of gravitational field equations is derived by replacing the three constraints with new ones requiring that geodesic paths remain geodesic against metric variations. The instability problem is then naturally solved. Implications for the cosmological constant $Λ$ are unchanged; the theory converges into EFE with nonzero $Λ$ by inflation, but $Λ$ varies on scales much larger than the present Hubble horizon. Then galaxies are formed only in small $Λ$ regions, and the cosmological constant problem is solved by the anthropic argument. Because of the increased degrees of freedom in metric dynamics, the theory predicts new non-oscillatory modes of metric anisotropy generated by quantum fluctuation during inflation, and CMB B-mode polarization would be observed differently from the standard predictions by general relativity.

gr-qc↗

arXiv2017

A New Constraint on Reionization from Evolution of the Ly$α$ Luminosity Function at $z\sim6-7$ Probed by a Deep Census of $z=7.0$ Ly$α$ Emitter Candidates to 0.3 $L^*$

We detect 20 $z=7.0$ Ly$α$ emitter (LAE) candidates to $L({\rm Ly}α) \geq 2 \times 10^{42}$ erg s$^{-1}$ or $0.3$ $L^*_{z=7}$ and in $6.1\times 10^5$ Mpc$^3$ volume in the Subaru Deep Field and the Subaru/XMM-Newton Deep Survey field by 82 and 37 hours of Subaru Suprime-Cam narrowband NB973 and reddest optical $y$-band imaging. We compare their Ly$α$ and UV luminosity functions (LFs) and densities and Ly$α$ equivalent widths (EWs) to those of $z=5.7$, 6.6 and 7.3 LAEs from previous Suprime-Cam surveys. The Ly$α$ LF (density) rapidly declines by a factor of $\times$1.5 (1.9) in $L({\rm Ly}α)$ at $z=5.7-6.6$ (160 Myr), $\times$1.5 (1.6) at $z=6.6-7.0$ (60 Myr) at the faint end and $\times$2.0 (3.8) at $z=7.0-7.3$ (40 Myr). Also, in addition to the systematic decrease in EW at $z=5.7-6.6$ previously found, 2/3 of the $z=7.0$ LAEs detected in the UV continuum exhibit lower EWs than the $z=6.6$ ones. Moreover, while the UV LF and density do not evolve at $z=5.7-6.6$, they modestly decline at $z=6.6-7.0$, implying galaxy evolution contributing to the decline of the Ly$α$ LF. Comparison of the $z=7.0$ Ly$α$ LF to the one predicted by an LAE evolution model further reveals that galaxy evolution alone cannot explain all the decline of Ly$α$ LF. If we attribute the discrepancy to Ly$α$ attenuation by neutral hydrogen, the intergalactic medium transmission of Ly$α$ photons at $z=7.0$ would be $T_{{\rm Ly}α}^{\rm IGM} \leq 0.6-0.7$. It is lower (higher) than $T_{{\rm Ly}α}^{\rm IGM}$ at $z=6.6$ (7.3) derived by previous studies, suggesting rapid increase in neutral fraction at $z > 6$.

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arXiv2016

Testing anthropic reasoning for the cosmological constant with a realistic galaxy formation model

The anthropic principle is one of the possible explanations for the cosmological constant ($Λ$) problem. In previous studies, a dark halo mass threshold comparable with our Galaxy must be assumed in galaxy formation to get a reasonably large probability of finding the observed small value, $P(<$$Λ_{\rm obs})$, though stars are found in much smaller galaxies as well. Here we examine the anthropic argument by using a semi-analytic model of cosmological galaxy formation, which can reproduce many observations such as galaxy luminosity functions. We calculate the probability distribution of $Λ$ by running the model code for a wide range of $Λ$, while other cosmological parameters and model parameters for baryonic processes of galaxy formation are kept constant. Assuming that the prior probability distribution is flat per unit $Λ$, and that the number of observers is proportional to stellar mass, we find $P(<$$Λ_{\rm obs}) = 6.7 \%$ without introducing any galaxy mass threshold. We also investigate the effect of metallicity; we find $P(<$$Λ_{\rm obs}) = 9.0 \%$ if observers exist only in galaxies whose metallicity is higher than the solar abundance. If the number of observers is proportional to metallicity, we find $P(<$$Λ_{\rm obs}) = 9.7 \%$. Since these probabilities are not extremely small, we conclude that the anthropic argument is a viable explanation, if the value of $Λ$ observed in our universe is determined by a probability distribution.

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arXiv2016

Initial Conditions of Inhomogeneous Universe and the Cosmological Constant Problem

Deriving the Einstein field equations (EFE) with matter fluid from the action principle is not straightforward, because mass conservation must be added as an additional constraint to make rest-frame mass density variable in reaction to metric variation. This can be avoided by introducing a constraint $δ(\sqrt{-g}) = 0$ to metric variations $δg^{μν}$, and then the cosmological constant $Λ$ emerges as an integration constant. This is a removal of one of the four constraints on initial conditions forced by EFE at the birth of the universe, and it may imply that EFE are unnecessarily restrictive about initial conditions. I then adopt a principle that the theory of gravity should be able to solve time evolution starting from arbitrary inhomogeneous initial conditions about spacetime and matter. The equations of gravitational fields satisfying this principle are obtained, by setting four auxiliary constraints on $δg^{μν}$ to extract six degrees of freedom for gravity. The cost of achieving this is a loss of general covariance, but these equations constitute a consistent theory if they hold in the special coordinate systems that can be uniquely specified with respect to the initial space-like hypersurface when the universe was born. This theory predicts that gravity is described by EFE with non-zero $Λ$ in a homogeneous patch of the universe created by inflation, but $Λ$ changes continuously across different patches. Then both the smallness and coincidence problems of the cosmological constant are solved by the anthropic argument. This is just a result of inhomogeneous initial conditions, not requiring any change of the fundamental physical laws in different patches.

gr-qc↗

arXiv2016

The Subaru FMOS Galaxy Redshift Survey (FastSound). II. The Emission Line Catalog and Properties of Emission Line Galaxies

We present basic properties of $\sim$3,300 emission line galaxies detected by the FastSound survey, which are mostly H$α$ emitters at $z \sim$ 1.2-1.5 in the total area of about 20 deg$^2$, with the H$α$ flux sensitivity limit of $\sim 1.6 \times 10^{-16} \rm erg \ cm^{-2} s^{-1}$ at 4.5 sigma. This paper presents the catalogs of the FastSound emission lines and galaxies, which will be open to the public in the near future. We also present basic properties of typical FastSound H$α$ emitters, which have H$α$ luminosities of $10^{41.8}$-$10^{43.3}$ erg/s, SFRs of 20--500 $M_\odot$/yr, and stellar masses of $10^{10.0}$--$10^{11.3}$ $M_\odot$. The 3D distribution maps for the four fields of CFHTLS W1--4 are presented, clearly showing large scale clustering of galaxies at the scale of $\sim$ 100--600 comoving Mpc. Based on 1,105 galaxies with detections of multiple emission lines, we estimate that contamination of non-H$α$ lines is about 4% in the single-line emission galaxies, which are mostly [OIII]$λ$5007. This contamination fraction is also confirmed by the stacked spectrum of all the FastSound spectra, in which H$α$, [NII]$λλ$6548,6583, [SII]$λλ$6717, 6731, and [OI]$λλ$6300,6364 are seen.

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arXiv2016

The Subaru FMOS galaxy redshift survey (FastSound). IV. New constraint on gravity theory from redshift space distortions at $z\sim 1.4$

We measure the redshift-space correlation function from a spectroscopic sample of 2783 emission line galaxies from the FastSound survey. The survey, which uses the Subaru Telescope and covers the redshift ranges of $1.19<z<1.55$, is the first cosmological study at such high redshifts. We detect clear anisotropy due to redshift-space distortions (RSD) both in the correlation function as a function of separations parallel and perpendicular to the line of sight and its quadrupole moment. RSD has been extensively used to test general relativity on cosmological scales at $z<1$. Adopting a LCDM cosmology with the fixed expansion history and no velocity dispersion $σ_{\rm v}=0$, and using the RSD measurements on scales above 8Mpc/h, we obtain the first constraint on the growth rate at the redshift, $f(z)σ_8(z)=0.482\pm 0.116$ at $z\sim 1.4$ after marginalizing over the galaxy bias parameter $b(z)σ_8(z)$. This corresponds to $4.2σ$ detection of RSD. Our constraint is consistent with the prediction of general relativity $fσ_8\sim 0.392$ within the $1-σ$ confidence level. When we allow $σ_{\rm v}$ to vary and marginalize it over, the growth rate constraint becomes $fσ_8=0.494^{+0.126}_{-0.120}$. We also demonstrate that by combining with the low-z constraints on $fσ_8$, high-z galaxy surveys like the FastSound can be useful to distinguish modified gravity models without relying on CMB anisotropy experiments.

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arXiv2015

High Precision Analyses of Lyman alpha Damping Wing of Gamma-Ray Bursts in the Reionization Era: On the Controversial Results from GRB 130606A at z = 5.91

The unprecedentedly bright afterglow of Swift GRB 130606A at z = 5.91 gave us a unique opportunity to probe the reionization era by high precision analyses of the redward damping wing of Ly alpha absorption, but the reported constraints on the neutral hydrogen fraction (f_HI) in intergalactic medium (IGM) derived from spectra taken by different telescopes are in contradiction. Here we examine the origin of this discrepancy by analyzing the spectrum taken by VLT with our own analysis code previously used to fit the Subaru spectrum. Though the VLT team reported no evidence for IGM HI using the VLT spectrum, we confirmed our previous result of preferring non-zero IGM HI (the best-fit f_HI ~ 0.06, when IGM HI extends to the GRB redshift). The fit residuals of the VLT spectrum by the model without IGM HI show the same systematic trend as the Subaru spectrum. We consider that the likely origin of the discrepancy between the two teams is the difference of the wavelength ranges adopted in the fittings; our wavelength range is wider than that of the VLT team, and also we avoided the shortest wavelength range of deep Ly alpha absorption (lambda_obs < 8426 A), because this region is dominated by HI in the host galaxy and the systematic uncertainty about host HI velocity distribution is large. We also study the sensitivity of these results to the adopted Ly alpha cross section formulae, ranging from the classical Lorentzian function to the most recent one taking into account fully quantum mechanical scattering. It is found that the preference for non-zero IGM HI is robust against the choice of the cross section formulae, but it is quantitatively not negligible and hence one should be careful in future analyses.

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arXiv2015

The Subaru FMOS Galaxy Redshift Survey (FastSound). III. The mass-metallicity relation and the fundamental metallicity relation at $z\sim1.4$

We present the results from a large near-infrared spectroscopic survey with Subaru/FMOS (\textit{FastSound}) consisting of $\sim$ 4,000 galaxies at $z\sim1.4$ with significant H$α$ detection. We measure the gas-phase metallicity from the [N~{\sc ii}]$λ$6583/H$α$ emission line ratio of the composite spectra in various stellar mass and star-formation rate bins. The resulting mass-metallicity relation generally agrees with previous studies obtained in a similar redshift range to that of our sample. No clear dependence of the mass-metallicity relation with star-formation rate is found. Our result at $z\sim1.4$ is roughly in agreement with the fundamental metallicity relation at $z\sim0.1$ with fiber aperture corrected star-formation rate. We detect significant [S~{\sc ii}]$λλ$6716,6731 emission lines from the composite spectra. The electron density estimated from the [S~{\sc ii}]$λλ$6716,6731 line ratio ranges from 10 -- 500 cm$^{-3}$, which generally agrees with that of local galaxies. On the other hand, the distribution of our sample on [N~{\sc ii}]$λ$6583/H$α$ vs. [S~{\sc ii}]$λλ$6716,6731/H$α$ is different from that found locally. We estimate the nitrogen-to-oxygen abundance ratio (N/O) from the N2S2 index, and find that the N/O in galaxies at $z\sim1.4$ is significantly higher than the local values at a fixed metallicity and stellar mass. The metallicity at $z\sim1.4$ recalculated with this N/O enhancement taken into account decreases by 0.1 -- 0.2 dex. The resulting metallicity is lower than the local fundamental metallicity relation.

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arXiv2015

The Subaru FMOS Galaxy Redshift Survey (FastSound). I. Overview of the Survey Targeting on H$α$ Emitters at $z \sim 1.4$

FastSound is a galaxy redshift survey using the near-infrared Fiber Multi-Object Spectrograph (FMOS) mounted on the Subaru Telescope, targeting H$α$ emitters at $z \sim 1.18$--$1.54$ down to the sensitivity limit of H$α$ flux $\sim 2 \times 10^{-16} \ \rm erg \ cm^{-2} s^{-1}$. The primary goal of the survey is to detect redshift space distortions (RSD), to test General Relativity by measuring the growth rate of large scale structure and to constrain modified gravity models for the origin of the accelerated expansion of the universe. The target galaxies were selected based on photometric redshifts and H$α$ flux estimates calculated by fitting spectral energy distribution (SED) models to the five optical magnitudes of the Canada France Hawaii Telescope Legacy Survey (CFHTLS) Wide catalog. The survey started in March 2012, and all the observations were completed in July 2014. In total, we achieved $121$ pointings of FMOS (each pointing has a $30$ arcmin diameter circular footprint) covering $20.6$ deg$^2$ by tiling the four fields of the CFHTLS Wide in a hexagonal pattern. Emission lines were detected from $\sim 4,000$ star forming galaxies by an automatic line detection algorithm applied to 2D spectral images. This is the first in a series of papers based on FastSound data, and we describe the details of the survey design, target selection, observations, data reduction, and emission line detections.

astro-ph.CO↗

arXiv2015

Metal Enrichment in the Fermi Bubbles as a Probe of Their Origin

The Fermi bubbles are gigantic gamma-ray structures in our Galaxy. The physical origin of the bubbles is still under debate. The leading scenarios can be divided into two categories. One is the nuclear star forming activity similar to extragalactic starburst galaxies and the other is the past active galactic nucleus (AGN) like activity of the Galactic center supermassive black hole. In this paper, we propose that metal abundance measurements will provide an important clue to probe their origin. Based on a simple spherically symmetric bubble model, we find that the generated metallicity and abundance pattern of the bubbles' gas strongly depend on assumed star formation or AGN activities. Star formation scenarios predict higher metallicities and abundance ratios of [O/Fe] and [Ne/Fe] than AGN scenarios do because of supernovae ejecta. Furthermore, the resultant abundance depends on the gamma-ray emission process because different mass injection histories are required for the different gamma-ray emission processes due to the acceleration and cooling time scales of non-thermal particles. Future X-ray missions such as ASTRO-H and Athena will give a clue to probe the origin of the bubbles through abundance measurements with their high energy resolution instruments.

astro-ph.HE↗