Pub Date : 2024-08-14DOI: 10.1051/0004-6361/202451356
Alexandra Veledina, Juri Poutanen, Anastasiia Bocharova, Alessandro Di Marco, Sofia V. Forsblom, Fabio La Monaca, Jakub Podgorný, Sergey S. Tsygankov, Andrzej A. Zdziarski, Varpu Ahlberg, David A. Green, Fabio Muleri, Lauren Rhodes, Stefano Bianchi, Enrico Costa, Michal Dovčiak, Vladislav Loktev, Michael McCollough, Paolo Soffitta, Rashid Sunyaev
Cygnus X-3 is an enigmatic X-ray binary that is both an exceptional accreting system and a cornerstone for population synthesis studies. Prominent X-ray and radio properties follow a well-defined pattern, and yet the physical reasons for the state changes observed in this system are not known. Recently, the presence of an optically thick envelope around the central source in the hard state was revealed using the X-ray polarization data obtained with the Imaging X-ray Polarimetry Explorer (IXPE). In this work we analyse IXPE data obtained in the ultrasoft (radio quenched) state of the source. The average polarization degree (PD) of 11.9 ± 0.5% at a polarization angle (PA) of 94° ±1° is inconsistent with the simple geometry of the accretion disc viewed at an intermediate inclination. The high PD, the blackbody-like spectrum, and the weakness of fluorescent iron line imply that the central source is hidden behind the optically thick outflow, similar to the hard-state geometry, and its beamed radiation is scattered, by the matter located along the funnel axis, towards our line of sight. In this picture the observed PD is directly related to the source inclination, which we conservatively determine to lie in the range 26° < i < 28°. Using the new polarimetric properties, we propose a scenario that can be responsible for the cyclic behaviour of the state changes in the binary.
天鹅座 X-3 是一个神秘的 X 射线双星，它既是一个特殊的增生系统，也是群体合成研究的基石。其显著的 X 射线和射电特性遵循一种明确的模式，然而在该系统中观测到的状态变化的物理原因却不得而知。最近，利用成像 X 射线偏振探测仪（IXPE）获得的 X 射线偏振数据，发现在硬态中心源周围存在一个光学厚包络。在这项工作中，我们分析了在该源的超软（射电淬火）状态下获得的 IXPE 数据。在偏振角（PA）为 94° ±1° 时，平均偏振度（PD）为 11.9 ± 0.5%，这与在中等倾角下观察吸积盘的简单几何形状不符。高PD、黑体样光谱和荧光铁线的弱化意味着中心源隐藏在光学厚的外流后面，类似于硬态几何，它的辐射被沿漏斗轴的物质向我们的视线散射。在这种情况下，观测到的 PD 与源倾角直接相关，我们保守地将其确定为 26° < i < 28°。利用新的偏振特性，我们提出了一种可能导致双星状态变化周期性行为的方案。
{"title":"Ultrasoft state of microquasar Cygnus X-3: X-ray polarimetry reveals the geometry of the astronomical puzzle","authors":"Alexandra Veledina, Juri Poutanen, Anastasiia Bocharova, Alessandro Di Marco, Sofia V. Forsblom, Fabio La Monaca, Jakub Podgorný, Sergey S. Tsygankov, Andrzej A. Zdziarski, Varpu Ahlberg, David A. Green, Fabio Muleri, Lauren Rhodes, Stefano Bianchi, Enrico Costa, Michal Dovčiak, Vladislav Loktev, Michael McCollough, Paolo Soffitta, Rashid Sunyaev","doi":"10.1051/0004-6361/202451356","DOIUrl":"https://doi.org/10.1051/0004-6361/202451356","url":null,"abstract":"Cygnus X-3 is an enigmatic X-ray binary that is both an exceptional accreting system and a cornerstone for population synthesis studies. Prominent X-ray and radio properties follow a well-defined pattern, and yet the physical reasons for the state changes observed in this system are not known. Recently, the presence of an optically thick envelope around the central source in the hard state was revealed using the X-ray polarization data obtained with the Imaging X-ray Polarimetry Explorer (IXPE). In this work we analyse IXPE data obtained in the ultrasoft (radio quenched) state of the source. The average polarization degree (PD) of 11.9 ± 0.5% at a polarization angle (PA) of 94° ±1° is inconsistent with the simple geometry of the accretion disc viewed at an intermediate inclination. The high PD, the blackbody-like spectrum, and the weakness of fluorescent iron line imply that the central source is hidden behind the optically thick outflow, similar to the hard-state geometry, and its beamed radiation is scattered, by the matter located along the funnel axis, towards our line of sight. In this picture the observed PD is directly related to the source inclination, which we conservatively determine to lie in the range 26° < <i>i<i/> < 28°. Using the new polarimetric properties, we propose a scenario that can be responsible for the cyclic behaviour of the state changes in the binary.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986516","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-14DOI: 10.1051/0004-6361/202451236
F. Urbina, P. Noterdaeme, T. A. M. Berg, S. Balashev, S. López, F. Bian
We present the first Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) observations of a quasar featuring a proximate molecular absorption system, SDSS J125917.31+030922.5. The proximate damped Lyα absorption acts as a natural coronagraph, removing the quasar emission over ∼40 Å in wavelength, and allows us to detect extended Lyα emission without the necessity of subtracting the quasar emission. This natural coronagraph permits the investigation of the quasar environment down to its inner regions (r < 20 kpc), where galaxy interactions or feedback processes should have the most noticeable effects. Our observations reveal a dense environment, with a highly asymmetric Lyα emission within 2″ (∼15 kpc), possibly shaped by a companion galaxy, and a southern extension of the nebulae to about 50 kpc, with rotation-like kinematic signature. The width of the Lyα emission is broadest closer to the quasar, indicating perturbed kinematics as expected if interactions and significant gas flows are present. The foreground absorbing system itself is redshifted by ≈400 km/s relative to the background quasar, and therefore is likely arising from gas moving toward the quasar. Finally two additional Lyα emitters are detected with > 10σ significance at 96 and 223 kpc from the quasar, making this field overdense relative to other similar observations of quasars at z ∼ 3. Our results support the hypothesis that quasars with proximate neutral and molecular absorption trace rich environments where galaxy interactions are at play and motivates further studies of H2-selected quasars to shed light on feeding and feedback processes.
{"title":"The rich galactic environment of a H2-absorption-selected quasar","authors":"F. Urbina, P. Noterdaeme, T. A. M. Berg, S. Balashev, S. López, F. Bian","doi":"10.1051/0004-6361/202451236","DOIUrl":"https://doi.org/10.1051/0004-6361/202451236","url":null,"abstract":"We present the first Very Large Telescope (VLT) Multi Unit Spectroscopic Explorer (MUSE) observations of a quasar featuring a proximate molecular absorption system, SDSS J125917.31+030922.5. The proximate damped Ly<i>α<i/> absorption acts as a natural coronagraph, removing the quasar emission over ∼40 Å in wavelength, and allows us to detect extended Ly<i>α<i/> emission without the necessity of subtracting the quasar emission. This natural coronagraph permits the investigation of the quasar environment down to its inner regions (<i>r<i/> < 20 kpc), where galaxy interactions or feedback processes should have the most noticeable effects. Our observations reveal a dense environment, with a highly asymmetric Ly<i>α<i/> emission within 2″ (∼15 kpc), possibly shaped by a companion galaxy, and a southern extension of the nebulae to about 50 kpc, with rotation-like kinematic signature. The width of the Ly<i>α<i/> emission is broadest closer to the quasar, indicating perturbed kinematics as expected if interactions and significant gas flows are present. The foreground absorbing system itself is redshifted by ≈400 km/s relative to the background quasar, and therefore is likely arising from gas moving toward the quasar. Finally two additional Ly<i>α<i/> emitters are detected with > 10<i>σ<i/> significance at 96 and 223 kpc from the quasar, making this field overdense relative to other similar observations of quasars at <i>z<i/> ∼ 3. Our results support the hypothesis that quasars with proximate neutral and molecular absorption trace rich environments where galaxy interactions are at play and motivates further studies of H<sub>2<sub/>-selected quasars to shed light on feeding and feedback processes.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-14DOI: 10.1051/0004-6361/202450798
Benedetta Spina, Sarah E. I. Bosman, Frederick B. Davies, Prakash Gaikwad, Yongda Zhu
Context. Recent observations have positioned the end point of the Epoch of Reionization (EoR) at a redshift of z ∼ 5.3. However, observations of the Lyman-α forest have not yet been able to discern whether reionization occurred slowly and late, with substantial neutral hydrogen persisting at a redshift of ∼6, or rapidly and earlier, with the apparent late end driven by the fluctuating ultraviolet background. Gunn-Peterson (GP) absorption troughs are solid indicators that reionization is not complete until z = 5.3, but whether they contain significantly neutral gas has not yet been proven.Aims. We aim to answer this question by directly measuring, for the first time, the neutral hydrogen fraction (xHI) at the end of the EoR (5 ≲ z ≲ 6) in high-redshift quasar spectra.Methods. For high neutral fractions, xHI ≳ 0.1, GP troughs exhibit damping wing (DW) absorption extending over 1000 km s−1 beyond the troughs. While conclusively detected in Lyman-α emission lines of quasars at z ≥ 7, DWs are challenging to observe in the general Lyman-α forest due to absorption complexities and small-scale stochastic transmission features.Results. We report the first successful identification of the stochastic DW signal adjacent to GP troughs at redshifts of z = 5.6 through careful stacking of the dark gaps in the Lyman-α forest (S/N = 6.3). We use the signal to present a measurement of the corresponding global xHI = 0.19 ± 0.07 at 1σ (2σ) at z = 5.6 and a limit of xHI < 0.44 at z = 5.9.Conclusions. The detection of this signal demonstrates the existence of substantially neutral islands near the conclusion of the EoR, unequivocally signaling a late-and-slow reionization scenario.
背景。最近的观测把再电离纪（EoR）的终点定位在 z ∼ 5.3 的红移上。然而，对莱曼-α森林的观测还无法辨别再电离是缓慢而晚期发生的，大量中性氢持续存在于红移∼6，还是快速而早期发生的，明显的晚期结束是由波动的紫外背景驱动的。贡-彼得森（Gunn-Peterson，GP）吸收波谷是再电离直到z = 5.3才完成的可靠指标，但其中是否含有大量中性气体尚未得到证实。我们首次在高红移类星体光谱中直接测量了再电离末期（5 ≲ z ≲ 6）的中性氢分数（xHI），旨在回答这个问题。对于高中性分数（xHI ≳ 0.1），GP波谷会表现出阻尼翼（DW）吸收，并延伸到波谷以外1000 km s-1以上。虽然在z≥7的类星体的莱曼-α发射线中最终探测到了DW，但由于吸收的复杂性和小尺度随机透射特征，在一般的莱曼-α森林中观测DW具有挑战性。我们报告了通过对莱曼-α森林（信噪比=6.3）中暗隙的仔细堆叠，首次成功地识别出了z=5.6红移时邻近GP波谷的随机DW信号。我们利用该信号在 z = 5.6 时的 1σ (2σ) 处测量到了相应的全局 xHI = 0.19 ± 0.07，并得出了 xHI z = 5.9 的极限结论。这个信号的探测证明了在EoR的末端附近存在着大量的中性岛，明确地表明了晚期慢再电离的情况。
{"title":"Damping wings in the Lyman-α forest: A model-independent measurement of the neutral fraction at 5.4 < z < 6.1","authors":"Benedetta Spina, Sarah E. I. Bosman, Frederick B. Davies, Prakash Gaikwad, Yongda Zhu","doi":"10.1051/0004-6361/202450798","DOIUrl":"https://doi.org/10.1051/0004-6361/202450798","url":null,"abstract":"<i>Context.<i/> Recent observations have positioned the end point of the Epoch of Reionization (EoR) at a redshift of <i>z<i/> ∼ 5.3. However, observations of the Lyman-<i>α<i/> forest have not yet been able to discern whether reionization occurred slowly and late, with substantial neutral hydrogen persisting at a redshift of ∼6, or rapidly and earlier, with the apparent late end driven by the fluctuating ultraviolet background. Gunn-Peterson (GP) absorption troughs are solid indicators that reionization is not complete until <i>z<i/> = 5.3, but whether they contain significantly neutral gas has not yet been proven.<i>Aims.<i/> We aim to answer this question by directly measuring, for the first time, the neutral hydrogen fraction (<i>x<i/><sub>HI<sub/>) at the end of the EoR (5 ≲ <i>z<i/> ≲ 6) in high-redshift quasar spectra.<i>Methods.<i/> For high neutral fractions, <i>x<i/><sub>HI<sub/> ≳ 0.1, GP troughs exhibit damping wing (DW) absorption extending over 1000 km s<sup>−1<sup/> beyond the troughs. While conclusively detected in Lyman-<i>α<i/> emission lines of quasars at <i>z<i/> ≥ 7, DWs are challenging to observe in the general Lyman-<i>α<i/> forest due to absorption complexities and small-scale stochastic transmission features.<i>Results.<i/> We report the first successful identification of the stochastic DW signal adjacent to GP troughs at redshifts of <i>z<i/> = 5.6 through careful stacking of the dark gaps in the Lyman-<i>α<i/> forest (S/N = 6.3). We use the signal to present a measurement of the corresponding global <i>x<i/><sub>HI<sub/> = 0.19 ± 0.07 at 1<i>σ<i/> (2<i>σ<i/>) at <i>z<i/> = 5.6 and a limit of <i>x<i/><sub>HI<sub/> < 0.44 at <i>z<i/> = 5.9.<i>Conclusions.<i/> The detection of this signal demonstrates the existence of substantially neutral islands near the conclusion of the EoR, unequivocally signaling a late-and-slow reionization scenario.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141986584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.1051/0004-6361/202450583
D. J. Lennon, P. L. Dufton, J. I. Villaseñor, N. Langer, C. J. Evans, H. Sana, W. D. Taylor
The spin evolution of stars in close binary systems can be strongly affected by tides. We investigate the rotational synchronisation of the stellar components for 69 SB1 systems and 14 SB2 B-type systems in the 30 Doradus region of the Large Magellanic Cloud using observations from the VFTS and BBC surveys. Their orbital periods range from a few to a few hundred days, while estimated primary masses for these systems are in the range ∼5−20 M⊙ with mass ratio ranges of q ∼ 0.03 − 0.5 and q ∼ 0.6 − 1.0 for the SB1 and SB2 systems, respectively. Projected rotational velocities of the stellar components have been compared with their synchronous velocities derived from the orbital periods. We find that effectively all systems with an orbital period of more than 10 days must be asynchronous, whilst all the systems with periods of less than 3 days are likely synchronised. In terms of the stellar fractional radius (r), our results imply that all systems with r < 0.1 are asynchronous, with those having r > 0.2 probably being synchronised. For the apparently synchronised systems, our results are more consistent with synchronisation at the mean orbital angular velocity rather than with that at periastron.
{"title":"Rotational synchronisation of B-type binaries in 30 Doradus","authors":"D. J. Lennon, P. L. Dufton, J. I. Villaseñor, N. Langer, C. J. Evans, H. Sana, W. D. Taylor","doi":"10.1051/0004-6361/202450583","DOIUrl":"https://doi.org/10.1051/0004-6361/202450583","url":null,"abstract":"The spin evolution of stars in close binary systems can be strongly affected by tides. We investigate the rotational synchronisation of the stellar components for 69 SB1 systems and 14 SB2 B-type systems in the 30 Doradus region of the Large Magellanic Cloud using observations from the VFTS and BBC surveys. Their orbital periods range from a few to a few hundred days, while estimated primary masses for these systems are in the range ∼5−20 <i>M<i/><sub>⊙<sub/> with mass ratio ranges of <i>q<i/> ∼ 0.03 − 0.5 and <i>q<i/> ∼ 0.6 − 1.0 for the SB1 and SB2 systems, respectively. Projected rotational velocities of the stellar components have been compared with their synchronous velocities derived from the orbital periods. We find that effectively all systems with an orbital period of more than 10 days must be asynchronous, whilst all the systems with periods of less than 3 days are likely synchronised. In terms of the stellar fractional radius (<i>r<i/>), our results imply that all systems with <i>r<i/> < 0.1 are asynchronous, with those having <i>r<i/> > 0.2 probably being synchronised. For the apparently synchronised systems, our results are more consistent with synchronisation at the mean orbital angular velocity rather than with that at periastron.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.1051/0004-6361/202450586
Ziyu Liu, Daniel Hestroffer, Josselin Desmars, Pedro David
Context. Binary asteroids are present in all populations of the Solar System, from near-Earth to trans-Neptunian regions. As is true for the small Solar System bodies (SSSBs), binary asteroids generally offer valuable insights into the formation of the Solar System, as well as its collisions and dynamic evolution. In particular, the binaries provide fundamental quantities and properties of these SSSBs, such as mass, angular momentum, and density, all of which are often hidden. The direct measurement of densities and porosities is of great value in revealing the gravitational aggregates and icy bodies that form the asteroid-comet continuum.Aims. Several observation techniques from space and ground-based platforms have provided many results in this regard. Here we show the value of the Gaia mission and its high-precision astrometry for analysing asteroid binaries and for individually deriving the masses of the components.Methods. We focus on the binary asteroid (4337) Arecibo, a member of the Themis family. We analysed the astrometry obtained in the Gaia FPR catalogue release, and performed orbital fitting for both the heliocentric orbit of the system and the relative orbit of the binary components.Results. We obtain an estimation of the component masses and their flux ratio, and derive bulk densities ρ1 ≈ 1.2 and ρ2 ≈ 1.6 for the primary and the secondary, respectively. The results are consistent with an ice-rich body in the outer main belt. They also show a significantly denser secondary or a less closely packed primary. Constraints on these densities and on macroscopic porosities are nevertheless limited by our poor knowledge of the sizes of the components. Observations of future mutual events, and of stellar occultations predicted in 2024–2025, will be essential for improving our knowledge of this system and its formation.
{"title":"Asteroid (4337) Arecibo: Two ice-rich bodies forming a binary","authors":"Ziyu Liu, Daniel Hestroffer, Josselin Desmars, Pedro David","doi":"10.1051/0004-6361/202450586","DOIUrl":"https://doi.org/10.1051/0004-6361/202450586","url":null,"abstract":"<i>Context.<i/> Binary asteroids are present in all populations of the Solar System, from near-Earth to trans-Neptunian regions. As is true for the small Solar System bodies (SSSBs), binary asteroids generally offer valuable insights into the formation of the Solar System, as well as its collisions and dynamic evolution. In particular, the binaries provide fundamental quantities and properties of these SSSBs, such as mass, angular momentum, and density, all of which are often hidden. The direct measurement of densities and porosities is of great value in revealing the gravitational aggregates and icy bodies that form the asteroid-comet continuum.<i>Aims.<i/> Several observation techniques from space and ground-based platforms have provided many results in this regard. Here we show the value of the <i>Gaia<i/> mission and its high-precision astrometry for analysing asteroid binaries and for individually deriving the masses of the components.<i>Methods.<i/> We focus on the binary asteroid (4337) Arecibo, a member of the Themis family. We analysed the astrometry obtained in the <i>Gaia<i/> FPR catalogue release, and performed orbital fitting for both the heliocentric orbit of the system and the relative orbit of the binary components.<i>Results.<i/> We obtain an estimation of the component masses and their flux ratio, and derive bulk densities <i>ρ<i/><sub>1<sub/> ≈ 1.2 and <i>ρ<i/><sub>2<sub/> ≈ 1.6 for the primary and the secondary, respectively. The results are consistent with an ice-rich body in the outer main belt. They also show a significantly denser secondary or a less closely packed primary. Constraints on these densities and on macroscopic porosities are nevertheless limited by our poor knowledge of the sizes of the components. Observations of future mutual events, and of stellar occultations predicted in 2024–2025, will be essential for improving our knowledge of this system and its formation.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.1051/0004-6361/202348779
K.-Y. Huang, D. Abbink, S. Viti, S. García-Burillo
Context. The outflowing molecular gas in the circumnuclear disc (CND) of the nearby (D = 14 Mpc) AGN-starburst composite galaxy NGC 1068 is considered as a manifestation of ongoing AGN feedback. The large spread of velocities from the outflowing gas is likely driving various kinds of shock chemistry across the CND.Aims. We performed a multiline molecular study using CH3OH with the aim of characterizing the gas properties probed by CH3OH in the CND of NGC 1068 and investigating its potential association with molecular shocks.Methods. Multi-transition CH3OH were imaged at the resolution of with the Atacama Large Millimeter/submillimeter Array (ALMA). We performed a non-LTE radiative transfer analysis coupled with a Bayesian inference process in order to determine the gas properties such as the gas volume density and the gas kinetic temperature.Results. The gas densities traced by CH3OH point to ∼106 cm–3 across all the CND regions. The gas kinetic temperature cannot be well constrained in any of the CND regions, though the inferred temperature is likely low (≲100 K).Conclusions. The low gas temperature traced by CH3OH suggests shocks and subsequent fast cooling as the origin of the observed gas-phase CH3OH abundance. We also note that the E-/A-isomer column-density ratio inferred is fairly close to unity, which is, interestingly, different from the Galactic measurements in the literature. It remains inconclusive whether CH3OH exclusively traces slow and non-dissociative shocks, or whether the CH3OH abundance can actually be boosted in both fast and slow shocks.
{"title":"Multi-transition study of methanol towards NGC 1068 with ALMA","authors":"K.-Y. Huang, D. Abbink, S. Viti, S. García-Burillo","doi":"10.1051/0004-6361/202348779","DOIUrl":"https://doi.org/10.1051/0004-6361/202348779","url":null,"abstract":"<i>Context.<i/> The outflowing molecular gas in the circumnuclear disc (CND) of the nearby (<i>D<i/> = 14 Mpc) AGN-starburst composite galaxy NGC 1068 is considered as a manifestation of ongoing AGN feedback. The large spread of velocities from the outflowing gas is likely driving various kinds of shock chemistry across the CND.<i>Aims.<i/> We performed a multiline molecular study using CH<sub>3<sub/>OH with the aim of characterizing the gas properties probed by CH<sub>3<sub/>OH in the CND of NGC 1068 and investigating its potential association with molecular shocks.<i>Methods.<i/> Multi-transition CH<sub>3<sub/>OH were imaged at the resolution of with the Atacama Large Millimeter/submillimeter Array (ALMA). We performed a non-LTE radiative transfer analysis coupled with a Bayesian inference process in order to determine the gas properties such as the gas volume density and the gas kinetic temperature.<i>Results.<i/> The gas densities traced by CH<sub>3<sub/>OH point to ∼10<sup>6<sup/> cm<sup>–3<sup/> across all the CND regions. The gas kinetic temperature cannot be well constrained in any of the CND regions, though the inferred temperature is likely low (≲100 K).<i>Conclusions.<i/> The low gas temperature traced by CH<sub>3<sub/>OH suggests shocks and subsequent fast cooling as the origin of the observed gas-phase CH<sub>3<sub/>OH abundance. We also note that the E-/A-isomer column-density ratio inferred is fairly close to unity, which is, interestingly, different from the Galactic measurements in the literature. It remains inconclusive whether CH<sub>3<sub/>OH exclusively traces slow and non-dissociative shocks, or whether the CH<sub>3<sub/>OH abundance can actually be boosted in both fast and slow shocks.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973935","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.1051/0004-6361/202451053
N. Liu, Z. Zhu, J.-C. Liu
Context. The motion of the Solar System barycenter (SSB), the spatial origin of the International Celestial Reference System, causes a directional displacement known as secular aberration. The secular aberration drift caused by the galactocentric acceleration of the SSB has been modeled in the third generation of the International Celestial Reference Frame.Aims. We aim to address another secular aberration drift effect due to the change in the line-of-sight direction and study its implications for stellar proper motions.Methods. We derived a complete formula for the secular aberration drift and computed its influence on stellar proper motion based on the astrometric data in Gaia Data Release 3.Results. We find that the secular aberration drift due to the change in the line-of-sight direction tends to decrease the observed proper motions for stars with galactic longitudes between 0° and 180°, and increase the observed proper motion for stars in the remaining region. If this secular aberration drift effect is ignored, it will induce an additional proper motion of > 1 mas yr−1 for 84 stars and > 0.02 mas yr−1 for 5 944 879 stars, which is comparable to or several times greater than the typical formal uncertainty of the Gaia proper motion measurements at G < 13.Conclusions. The secular aberration drift due to the change in the line-of-sight direction and the acceleration of the SSB should be modeled to make the stellar reference frame consistent with the extragalactic reference frame.
{"title":"Secular aberration drift in stellar proper motions","authors":"N. Liu, Z. Zhu, J.-C. Liu","doi":"10.1051/0004-6361/202451053","DOIUrl":"https://doi.org/10.1051/0004-6361/202451053","url":null,"abstract":"<i>Context.<i/> The motion of the Solar System barycenter (SSB), the spatial origin of the International Celestial Reference System, causes a directional displacement known as secular aberration. The secular aberration drift caused by the galactocentric acceleration of the SSB has been modeled in the third generation of the International Celestial Reference Frame.<i>Aims.<i/> We aim to address another secular aberration drift effect due to the change in the line-of-sight direction and study its implications for stellar proper motions.<i>Methods.<i/> We derived a complete formula for the secular aberration drift and computed its influence on stellar proper motion based on the astrometric data in <i>Gaia<i/> Data Release 3.<i>Results.<i/> We find that the secular aberration drift due to the change in the line-of-sight direction tends to decrease the observed proper motions for stars with galactic longitudes between 0° and 180°, and increase the observed proper motion for stars in the remaining region. If this secular aberration drift effect is ignored, it will induce an additional proper motion of > 1 mas yr<sup>−1<sup/> for 84 stars and > 0.02 mas yr<sup>−1<sup/> for 5 944 879 stars, which is comparable to or several times greater than the typical formal uncertainty of the <i>Gaia<i/> proper motion measurements at <i>G<i/> < 13.<i>Conclusions.<i/> The secular aberration drift due to the change in the line-of-sight direction and the acceleration of the SSB should be modeled to make the stellar reference frame consistent with the extragalactic reference frame.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-12DOI: 10.1051/0004-6361/202450412
Jian-wen Zhou, Pavel Kroupa, Sami Dib
We used the dendrogram algorithm to decompose the surface density distributions of stars into hierarchical structures. These structures were tied to the multiscale structures of star clusters. A similar power-law for the mass-size relation of star clusters measured at different scales suggests a self-similar structure of star clusters. We used the minimum spanning tree method to measure the separations between clusters and gas clumps in each massive star-forming region. The separations between clusters, between clumps, and between clusters and clumps were comparable, which indicates that the evolution from clump to embedded cluster proceeds in isolation and locally, and does not affect the surrounding objects significantly. By comparing the mass functions of the ATLASGAL clumps and the identified embedded clusters, we confirm that a constant star formation efficiency of ≈0.33 can be a typical value for the ATLASGAL clumps.
{"title":"Self-similar cluster structures in massive star-forming regions: Isolated evolution from clumps to embedded clusters","authors":"Jian-wen Zhou, Pavel Kroupa, Sami Dib","doi":"10.1051/0004-6361/202450412","DOIUrl":"https://doi.org/10.1051/0004-6361/202450412","url":null,"abstract":"We used the dendrogram algorithm to decompose the surface density distributions of stars into hierarchical structures. These structures were tied to the multiscale structures of star clusters. A similar power-law for the mass-size relation of star clusters measured at different scales suggests a self-similar structure of star clusters. We used the minimum spanning tree method to measure the separations between clusters and gas clumps in each massive star-forming region. The separations between clusters, between clumps, and between clusters and clumps were comparable, which indicates that the evolution from clump to embedded cluster proceeds in isolation and locally, and does not affect the surrounding objects significantly. By comparing the mass functions of the ATLASGAL clumps and the identified embedded clusters, we confirm that a constant star formation efficiency of ≈0.33 can be a typical value for the ATLASGAL clumps.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-09DOI: 10.1051/0004-6361/202347479
H. Sana, F. Tramper, M. Abdul-Masih, R. Blomme, K. Dsilva, G. Maravelias, L. Martins, A. Mehner, A. Wofford, G. Banyard, C. L. Barbosa, J. Bestenlehner, C. Hawcroft, D. John Hillier, H. Todt, C. J. K. Larkin, L. Mahy, F. Najarro, V. Ramachandran, M. C. Ramírez-Tannus, M. M. Rubio-Díez, A. A. C. Sander, T. Shenar, J. S. Vink, F. Backs, S. A. Brands, P. Crowther, L. Decin, A. de Koter, W.-R. Hamann, C. Kehrig, R. Kuiper, L. Oskinova, D. Pauli, J. Sundqvist, O. Verhamme
Context. The XShootU project aims to obtain ground-based optical to near-infrared spectroscopy of all targets observed by the Hubble Space Telescope (HST) under the Director’s Discretionary program ULLYSES. Using the medium-resolution spectrograph X-shooter, spectra of 235 OB and Wolf-Rayet (WR) stars in subsolar metallicity environments have been secured. The bulk of the targets belong to the Large and Small Magellanic Clouds, with the exception of three stars in NGC 3109 and Sextans A.Aims. This second paper in the series focuses on the optical observations of Magellanic Clouds targets. It describes the uniform reduction of the UVB (300–560 nm) and VIS (550–1020 nm) XShootU data as well as the preparation of advanced data products that are suitable for homogeneous scientific analyses.Methods. The data reduction of the RAW data is based on the ESO CPL X-shooter pipeline. We paid particular attention to the determination of the response curves. This required equal flat-fielding of the science and flux standard star data and the derivation of improved flux standard models. The pipeline products were then processed with our own set of routines to produce a series of advanced data products. In particular, we implemented slit-loss correction, absolute flux calibration, (semi-)automatic rectification to the continuum, and a correction for telluric lines. The spectra of individual epochs were further corrected for the barycentric motion, re-sampled and co-added, and the spectra from the two arms were merged into a single flux-calibrated spectrum covering the entire optical range with maximum signal-to-noise ratio.Results. We identify and describe an undocumented recurrent ghost visible on the RAW data. We present an improved flat-fielding strategy that limits artifacts when the SCIENCE and FLUX standard stars are observed on different nights. The improved FLUX standard models and the new grid of anchor points limit artifacts of the response curve correction, for example on the shape of the wings of the Balmer lines, from a couple of per cent of the continuum level to less than 0.5%. We confirm the presence of a radial velocity shift of about 3.5 km s−1 between the UVB and the VIS arm of X-shooter and that there are no short term variations impacting the RV measurements. RV precision better than 1 km s-1 can be obtained on sharp telluric lines while RV precision on the order of 2 to 3 km s-1 is obtained on data with the best S/N.Conclusions. For each target observed by XShootU, we provide three types of data products: (i) two-dimensional spectra for each UVB and VIS exposure before and after correction for the instrument response; (ii) one-dimensional UVB and VIS spectra as produced by the X-shooter pipeline before and after response-correction, and applying various processing, including absolute flux calibration, telluric removal, normalization and barycentric correction; and (i
背景。XShootU项目旨在获得哈勃太空望远镜（HST）在局长酌处计划ULLYSES下观测到的所有目标的地基光学到近红外光谱。利用中分辨率摄谱仪X-shooter，已经获得了235颗处于亚太阳金属性环境中的OB星和Wolf-Rayet（WR）星的光谱。大部分目标属于大麦哲伦云和小麦哲伦云，只有 NGC 3109 和 Sextans A 中的三颗恒星除外。本系列的第二篇论文重点介绍麦哲伦云目标的光学观测。它介绍了对 UVB（300-560 nm）和 VIS（550-1020 nm）XShootU 数据的统一缩减，以及适合同质科学分析的高级数据产品的制备。对 RAW 数据的还原基于 ESO CPL X-shooter 管道。我们特别关注响应曲线的确定。这需要对科学星数据和通量标准星数据进行同等平场处理，并推导出改进的通量标准模型。然后用我们自己的一套程序对管道产品进行处理，以产生一系列先进的数据产品。特别是，我们实施了狭缝损耗校正、绝对通量校准、连续面（半）自动校正和碲线校正。单个纪元的光谱还进一步进行了偏心运动校正、重新采样和合并，来自两臂的光谱被合并成一个单一的通量校正光谱，以最大信噪比覆盖整个光学范围。我们发现并描述了 RAW 数据中可见的一个未记录的经常性幽灵。我们提出了一种改进的平场策略，可以限制在不同夜晚观测 SCIENCE 和 FLUX 标准星时产生的伪影。改进后的 FLUX 标准模型和新的锚点网格限制了响应曲线校正的伪影，例如巴尔默线的翼形，从连续波水平的百分之几降低到 0.5%以下。我们证实在 X-shooter 的 UVB 和 VIS 臂之间存在约 3.5 km s-1 的径向速度偏移，并且没有短期变化影响 RV 测量。在尖锐的碲线上可以获得优于 1 千米/秒的 RV 精度，而在具有最佳信噪比的数据上可以获得 2 至 3 千米/秒的 RV 精度。对于 XShootU 观测到的每个目标，我们都提供了三种类型的数据产品：(i) 仪器响应校正前后每次 UVB 和 VIS 曝光的二维光谱；(ii) 响应校正前后由 X-shooter 管道生成的一维 UVB 和 VIS 光谱，并应用了各种处理，包括绝对通量校准、碲去除、归一化和偏心校正；以及 (iii) 全光学范围内的共加通量校准和校正光谱，其中所有可用的 XShootU 曝光都合并在一起。对于绝大多数目标，在 UVB 和 VIS 共加光谱中，每个分辨率元素的最终信噪比都在 200 以上。缩减后的数据和高级科学数据产品已向社会公布。这些数据与 HST 紫外 ULLYSES 数据一起，可以实现各种科学目标，从详细的恒星大气和恒星风研究、用于种群合成的经验库，到本地星云环境研究和亚太阳金属性环境中大质量恒星的反馈。
{"title":"X-Shooting ULLYSES: Massive stars at low metallicity","authors":"H. Sana, F. Tramper, M. Abdul-Masih, R. Blomme, K. Dsilva, G. Maravelias, L. Martins, A. Mehner, A. Wofford, G. Banyard, C. L. Barbosa, J. Bestenlehner, C. Hawcroft, D. John Hillier, H. Todt, C. J. K. Larkin, L. Mahy, F. Najarro, V. Ramachandran, M. C. Ramírez-Tannus, M. M. Rubio-Díez, A. A. C. Sander, T. Shenar, J. S. Vink, F. Backs, S. A. Brands, P. Crowther, L. Decin, A. de Koter, W.-R. Hamann, C. Kehrig, R. Kuiper, L. Oskinova, D. Pauli, J. Sundqvist, O. Verhamme","doi":"10.1051/0004-6361/202347479","DOIUrl":"https://doi.org/10.1051/0004-6361/202347479","url":null,"abstract":"<i>Context<i/>. The XShootU project aims to obtain ground-based optical to near-infrared spectroscopy of all targets observed by the <i>Hubble<i/> Space Telescope (HST) under the Director’s Discretionary program ULLYSES. Using the medium-resolution spectrograph X-shooter, spectra of 235 OB and Wolf-Rayet (WR) stars in subsolar metallicity environments have been secured. The bulk of the targets belong to the Large and Small Magellanic Clouds, with the exception of three stars in NGC 3109 and Sextans A.<i>Aims<i/>. This second paper in the series focuses on the optical observations of Magellanic Clouds targets. It describes the uniform reduction of the UVB (300–560 nm) and VIS (550–1020 nm) XShootU data as well as the preparation of advanced data products that are suitable for homogeneous scientific analyses.<i>Methods<i/>. The data reduction of the RAW data is based on the ESO CPL X-shooter pipeline. We paid particular attention to the determination of the response curves. This required equal flat-fielding of the science and flux standard star data and the derivation of improved flux standard models. The pipeline products were then processed with our own set of routines to produce a series of advanced data products. In particular, we implemented slit-loss correction, absolute flux calibration, (semi-)automatic rectification to the continuum, and a correction for telluric lines. The spectra of individual epochs were further corrected for the barycentric motion, re-sampled and co-added, and the spectra from the two arms were merged into a single flux-calibrated spectrum covering the entire optical range with maximum signal-to-noise ratio.<i>Results<i/>. We identify and describe an undocumented recurrent ghost visible on the RAW data. We present an improved flat-fielding strategy that limits artifacts when the SCIENCE and FLUX standard stars are observed on different nights. The improved FLUX standard models and the new grid of anchor points limit artifacts of the response curve correction, for example on the shape of the wings of the Balmer lines, from a couple of per cent of the continuum level to less than 0.5%. We confirm the presence of a radial velocity shift of about 3.5 km s<sup>−1<sup/> between the UVB and the VIS arm of X-shooter and that there are no short term variations impacting the RV measurements. RV precision better than 1 km s<sup>-1<sup/> can be obtained on sharp telluric lines while RV precision on the order of 2 to 3 km s<sup>-1<sup/> is obtained on data with the best S/N.<i>Conclusions<i/>. For each target observed by XShootU, we provide three types of data products: (i) two-dimensional spectra for each UVB and VIS exposure before and after correction for the instrument response; (ii) one-dimensional UVB and VIS spectra as produced by the X-shooter pipeline before and after response-correction, and applying various processing, including absolute flux calibration, telluric removal, normalization and barycentric correction; and (i","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973837","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-09DOI: 10.1051/0004-6361/202348834
J. R. Knies, M. Sasaki, W. Becker, T. Liu, G. Ponti, P. P. Plucinsky
Aims. The Gemini-Monoceros X-ray enhancement is a rich field for studying diffuse X-ray emission and supernova remnants (SNRs). Most SNRs in this part of the sky are notoriously difficult to observe due to their large extent. With the launch of the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Röntgen-Gamma platform in 2019, we are now able to fully study those objects for the first time with CCD resolution. Many of the SNRs in the vicinity are suspected to be very old remnants, which are severely understudied in X-rays due to numerous observational challenges. In addition, the identification of new faint large SNRs might help to solve the long-standing discrepancy between the observed and expected number of Galactic SNRs.Methods. We performed a detailed X-ray spectral analysis of the entire Gemini-Monoceros X-ray enhancement and a detailed background analysis of the vicinity, which allowed us to model the background with a high precision inside the X-ray enhancement. We also made use of multiwavelength data to better understand the morphology and to constrain the distances to the different sources. Based on the spectral analysis, we estimated the properties of the sources and calculated a grid of model SNRs to determine the individual SNR properties.Results. Most of the diffuse plasma of the Monogem Ring SNR is well described by a single nonequilibrium ionization (NEI) component with an average temperature of kT = 0.14 ± 0.03 keV. We obtain an age of ≈1.2 × 105 yr – consistent with PSR B0656+14 – for the Monogem Ring and an explosion energy typical for a core-collapse (CC) supernova (SN). In the southeast, we found evidence for a significant temperature enhancement and a second plasma component. Our findings show that a scenario of two SNRs at ≈300 pc is likely, with the new candidate having an age of ≈50 000 yr. We were also able to improve on previous results for the Monoceros Loop and PKS 0646+06 SNRs by disentangling the foreground diffuse emission of the Monogem Ring SNR. We obtained significantly higher temperatures than previous studies, and for PKS 0646+06 a much lower estimated age of the SNR. We also found a new SNR candidate G190.4+12.5 which most likely is located at D > 1.5 kpc, expanding into a low density medium at a high distance from the Galactic plane, with an estimated age of 40 000–60 000 yr.
目的双子座-木卫二 X 射线增强是研究漫射 X 射线发射和超新星残余（SNR）的一个丰富领域。这部分天空中的大多数超新星残骸由于范围大而难以观测。随着 2019 年搭载在 Spektrum-Röntgen-Gamma 平台上的扩展伦琴巡天成像望远镜阵列（eROSITA）的发射，我们现在第一次能够以 CCD 分辨率对这些天体进行全面研究。附近的许多自发核反应堆被怀疑是非常古老的残余物，由于观测方面的诸多挑战，它们在 X 射线方面的研究严重不足。此外，发现新的暗弱大型自发核反应堆可能有助于解决银河系自发核反应堆的观测数量与预期数量之间长期存在的差异。我们对整个双子座-莫诺塞洛斯 X 射线增强区进行了详细的 X 射线光谱分析，并对附近地区进行了详细的背景分析，从而能够对 X 射线增强区内的背景进行高精度建模。我们还利用多波长数据来更好地了解其形态，并对不同来源的距离进行约束。在光谱分析的基础上，我们估算了源的属性，并计算出了一个 SNR 模型网格，以确定单个 SNR 的属性。Monogem Ring SNR 的大部分弥漫等离子体都可以用平均温度为 kT = 0.14 ± 0.03 keV 的单一非平衡电离（NEI）成分很好地描述。我们得到了 Monogem Ring 的年龄≈1.2 × 105 年--与 PSR B0656+14 一致，爆炸能量为典型的核坍缩（CC）超新星（SN）。在东南部，我们发现了温度显著升高和第二个等离子体成分的证据。我们的研究结果表明，在≈300 pc处可能存在两个SNR，新的候选SNR的年龄≈50000年。我们还通过分离Monogem Ring SNR的前景弥散发射，改进了以前对Monoceros Loop和PKS 0646+06 SNR的研究结果。我们得到的温度明显高于之前的研究，而对于 PKS 0646+06 SNR，估计的年龄要低得多。我们还发现了一个新的SNR候选者G190.4+12.5，它很可能位于D > 1.5 kpc处，在距离银河系平面很远的地方向低密度介质膨胀，估计年龄为40000-60000年。
{"title":"A new understanding of the Gemini-Monoceros X-ray enhancement from discoveries with eROSITA","authors":"J. R. Knies, M. Sasaki, W. Becker, T. Liu, G. Ponti, P. P. Plucinsky","doi":"10.1051/0004-6361/202348834","DOIUrl":"https://doi.org/10.1051/0004-6361/202348834","url":null,"abstract":"<i>Aims.<i/> The Gemini-Monoceros X-ray enhancement is a rich field for studying diffuse X-ray emission and supernova remnants (SNRs). Most SNRs in this part of the sky are notoriously difficult to observe due to their large extent. With the launch of the extended ROentgen Survey with an Imaging Telescope Array (eROSITA) on board the Spektrum-Röntgen-Gamma platform in 2019, we are now able to fully study those objects for the first time with CCD resolution. Many of the SNRs in the vicinity are suspected to be very old remnants, which are severely understudied in X-rays due to numerous observational challenges. In addition, the identification of new faint large SNRs might help to solve the long-standing discrepancy between the observed and expected number of Galactic SNRs.<i>Methods.<i/> We performed a detailed X-ray spectral analysis of the entire Gemini-Monoceros X-ray enhancement and a detailed background analysis of the vicinity, which allowed us to model the background with a high precision inside the X-ray enhancement. We also made use of multiwavelength data to better understand the morphology and to constrain the distances to the different sources. Based on the spectral analysis, we estimated the properties of the sources and calculated a grid of model SNRs to determine the individual SNR properties.<i>Results.<i/> Most of the diffuse plasma of the Monogem Ring SNR is well described by a single nonequilibrium ionization (NEI) component with an average temperature of <i>kT =<i/> 0.14 ± 0.03 keV. We obtain an age of ≈1.2 × 10<sup>5<sup/> yr – consistent with PSR B0656+14 – for the Monogem Ring and an explosion energy typical for a core-collapse (CC) supernova (SN). In the southeast, we found evidence for a significant temperature enhancement and a second plasma component. Our findings show that a scenario of two SNRs at ≈300 pc is likely, with the new candidate having an age of ≈50 000 yr. We were also able to improve on previous results for the Monoceros Loop and PKS 0646+06 SNRs by disentangling the foreground diffuse emission of the Monogem Ring SNR. We obtained significantly higher temperatures than previous studies, and for PKS 0646+06 a much lower estimated age of the SNR. We also found a new SNR candidate G190.4+12.5 which most likely is located at <i>D<i/> > 1.5 kpc, expanding into a low density medium at a high distance from the Galactic plane, with an estimated age of 40 000–60 000 yr.","PeriodicalId":8571,"journal":{"name":"Astronomy & Astrophysics","volume":null,"pages":null},"PeriodicalIF":6.5,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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