Pub Date : 2024-07-01DOI: 10.1051/0004-6361/202449839
J. Nadolny, J. Michał Michałowski, M. Parente, Jens Hjorth, C. Gall, A. Leśniewska, M. Solar, Przemysław Nowaczyk, O. Ryzhov
Removing the cold interstellar medium (ISM) from a galaxy is essential to quenching star formation, however, the exact mechanism behind this process remains unclear. The objective of this work is to find the mechanism responsible for dust and gas removal in simulated early-type galaxies. We studied a statistically significant sample of massive ( simulated early-type galaxies in a redshift range of 0.02--0.32 in the context of its ISM properties. In particular, we investigated the cold dust and gas removal timescales, the cold gas inflows, and their relation with black hole mass. We also investigated the evolution of galaxies in the dust mass and star formation rate (SFR) plane and the influence of merger events. Finally, we broke down the dust destruction mechanisms to find which (if any) of the implemented processes dominate as a function of a galaxy's stellar age. We find a good agreement with previous observational works dealing with the timescales of dust and removal from early-type galaxies. When considering the dust-to-stellar-mass ratio as a function of time in simulations, we recovered a similar decline as in the observational sample as a function of stellar age, validating its use for timing the ISM decline. Moreover, we recovered the observed relation between dust mass and the SFR for actively star-forming galaxies, as well as that of passive early-type galaxies. We also show that starburst galaxies form their own sequence on the dust mass and SFR plot in the form of $ dust, SB SFR ) + 6.533,$ with a $2 scatter of 0.32. Finally, we find that type II supernova reverse shocks dominate the dust destruction at the early stages of early-type galaxy evolution; however, we also see that at later times, stellar feedback becomes more important. We show that merger events lead to morphological transformations by increasing the bulge-to-total stellar mass ratio followed by an increase in black hole masses. The black hole feedback resulting from radio mode accretion prevents the hot halo gas from cooling, indirectly leading to a decrease in the SFR.
{"title":"The fate of the interstellar medium in early-type galaxies. IV. The impact of stellar feedback, mergers, and black holes on the cold interstellar medium in simulated galaxies.","authors":"J. Nadolny, J. Michał Michałowski, M. Parente, Jens Hjorth, C. Gall, A. Leśniewska, M. Solar, Przemysław Nowaczyk, O. Ryzhov","doi":"10.1051/0004-6361/202449839","DOIUrl":"https://doi.org/10.1051/0004-6361/202449839","url":null,"abstract":"Removing the cold interstellar\u0000medium (ISM) from a galaxy is essential to quenching star formation, however,\u0000the exact mechanism behind this process remains unclear. The objective of this work is to find the mechanism responsible for dust\u0000and gas removal in simulated early-type galaxies. We studied a statistically significant sample of massive ( simulated early-type galaxies in a redshift range of 0.02--0.32 in the context of its ISM properties. In particular, we investigated the cold dust and gas removal timescales, the cold gas inflows, and their relation with black hole mass. We also investigated the evolution of galaxies in the dust mass and star formation rate (SFR) plane and the influence of merger events. Finally, we broke\u0000down the dust destruction mechanisms to find which (if any) of the implemented\u0000processes dominate as a function of a galaxy's stellar age. We find a good agreement with previous observational works dealing with\u0000the timescales of dust and removal from early-type galaxies. When considering the dust-to-stellar-mass ratio as a function of time in simulations, we recovered a similar decline as in the observational sample as a function of stellar age, validating its use for timing the ISM decline. Moreover, we recovered the observed relation between dust mass and the SFR for actively star-forming galaxies, as well as that of passive early-type galaxies. We also show that starburst galaxies form their own sequence on the dust mass and SFR plot in the form of $ dust, SB SFR ) + 6.533,$\u0000with a $2 scatter of 0.32. Finally, we find that type II supernova reverse shocks dominate the dust destruction at the early stages of early-type galaxy evolution; however, we also see that at later times, stellar feedback becomes more important. We show that merger events lead to morphological transformations by increasing the bulge-to-total stellar mass ratio followed by an increase in black hole masses. The black hole feedback resulting from radio mode accretion prevents the hot halo gas from cooling, indirectly leading to a decrease in the SFR.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"15 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141715759","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1051/0004-6361/202451011
Holger S. P. Muller, V. Ilyushin, Arnaud Belloche, F. Lewen, S. Schlemmer
Methanol is an abundant and widespread molecule in the interstellar medium. The column density of its 18O isotopolog, CH$_3$18OH, is in some star-forming regions so high that the search for CH$_3$17OH is promising. But only very few transition frequencies of CH$_3$17OH with a microwave accuracy have been published prior to our investigation. We want to extend the very limited rotational line list of CH$_3$17OH to be able to search for this isotopolog in the interstellar medium. We recorded the rotational spectrum of CH$_3$17OH between 38 and 1095 GHz employing a methanol sample enriched in 17O to 20. A torsion-rotation Hamiltonian model based on the rho-axis method was employed to fit the data, as in our previous studies. We searched for rotational transitions of CH$_3$17OH in the imaging spectral line survey ReMoCA obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the high-mass star-forming region Sgr B2(N). The observed spectra were modeled under the assumption of local thermodynamic equilibrium (LTE). The assignments cover $0 J 45$, $K_a 16$, and mainly the $ t = 0$ and 1 torsional states. The Hamiltonian model describes our data well. The model was applied to derive a line list for radio-astronomical observations. We report a tentative detection of CH$_3$17OH along with secure detections of the more abundant isotopologs of methanol toward Sgr B2(N2b). The derived column densities yield isotopic ratios 12C/13C = 25, 16O/18O = 240, and 18O/17O = 3.3, which are consistent with values found earlier for other molecules in Sgr B2. The agreement between the 18O/17O isotopic ratio that we obtained for methanol and the 18O/17O ratios reported in the past for other molecules in Sgr B2(N) strongly supports our tentative interstellar identification of CH$_3$17OH. The accuracy of the derived line list is sufficient for further radio astronomical searches for this methanol isotopolog toward other star-forming regions.
{"title":"Investigation of the rotational spectrum of CH$_3$17OH and its tentative detection \u0000 toward Sagittarius B2(N)","authors":"Holger S. P. Muller, V. Ilyushin, Arnaud Belloche, F. Lewen, S. Schlemmer","doi":"10.1051/0004-6361/202451011","DOIUrl":"https://doi.org/10.1051/0004-6361/202451011","url":null,"abstract":"Methanol is an abundant and widespread molecule in the interstellar medium. The column \u0000 density of its 18O isotopolog, CH$_3$18OH, is in some star-forming regions so high \u0000 that the search for CH$_3$17OH is promising. But only very few transition frequencies \u0000 of CH$_3$17OH with a microwave accuracy have been published prior to our investigation. We want to extend the very limited rotational line list of CH$_3$17OH to be able \u0000 to search for this isotopolog in the interstellar medium. We recorded the rotational spectrum of CH$_3$17OH between 38 and 1095 GHz employing a \u0000 methanol sample enriched in 17O to 20. A torsion-rotation Hamiltonian model based on \u0000 the rho-axis method was employed to fit the data, as in our previous studies. \u0000 We searched for rotational transitions of CH$_3$17OH in the imaging spectral line survey \u0000 ReMoCA obtained with the Atacama Large Millimeter/submillimeter Array (ALMA) toward the \u0000 high-mass star-forming region Sgr B2(N). The observed spectra were modeled under the assumption \u0000 of local thermodynamic equilibrium (LTE). The assignments cover $0 J 45$, $K_a 16$, and mainly the $ t = 0$ and 1 \u0000 torsional states. The Hamiltonian model describes our data well. The model was applied to derive \u0000 a line list for radio-astronomical observations. \u0000 We report a tentative detection of CH$_3$17OH along with secure detections of the more \u0000 abundant isotopologs of methanol toward Sgr B2(N2b). The derived column densities yield \u0000 isotopic ratios 12C/13C = 25, 16O/18O = 240, and 18O/17O = 3.3, \u0000 which are consistent with values found earlier for other molecules in Sgr B2. The agreement between the 18O/17O isotopic ratio that we obtained for methanol \u0000 and the 18O/17O ratios reported in the past for other molecules in Sgr B2(N) \u0000 strongly supports our tentative interstellar identification of CH$_3$17OH. \u0000 The accuracy of the derived line list is sufficient for further radio astronomical \u0000 searches for this methanol isotopolog toward other star-forming regions.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"32 7","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141715890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-01DOI: 10.1051/0004-6361/202449676
A. C. U. D. Torino, Pino Torinese, Italy
We explore the radio properties of powerful (rest-frame luminosity $ at 500 MHz) high-redshift ($z 3.5$) quasars. The aim of this study is to gain a better understanding of radio-loud sources at the epoch when they reach the highest space density. We selected 29 radio-loud quasars at low radio frequencies (76 MHz). Their radio spectra, covering the range from 76 MHz to 5 GHz, are generally well reproduced by a single power law. We created samples that were matched in radio luminosity at lower redshift (from $z to $z to investigate any spectral evolution. We find that the fraction of flat-spectrum radio quasars (FSRQs) strongly increases with redshift (from $ 8$ at z=1.2 to $ 45$ at z$>$3.5). This effect is also observed in quasars with lower luminosities (down to $ The increase in the fraction of FSRQs with redshift corresponds to a decrease in the steep- spectrum radio quasars. This result can be explained when we assume that the beaming factor and the slope of the luminosity function do not change with redshift and if high-redshift radio-loud sources can be recognized as quasars only when they are seen at a small viewing angle ($ but most of them, about 90 are obscured in the UV and optical bands. We also found a trend for the size of radio sources to decrease with increasing redshift. Because projection effects are insufficient to cause this trend, we suggest that the large amount of gas causing the nuclear obscuration also hampers the growth of the more distant sources.
{"title":"The radio properties of z>3.5 quasars: Are most high-redshift radio-loud active galactic nuclei obscured?","authors":"A. C. U. D. Torino, Pino Torinese, Italy","doi":"10.1051/0004-6361/202449676","DOIUrl":"https://doi.org/10.1051/0004-6361/202449676","url":null,"abstract":"We explore the radio properties of powerful (rest-frame\u0000 luminosity $ at 500 MHz) high-redshift ($z 3.5$) quasars. The aim of this study is to gain a better understanding of radio-loud sources at the epoch when they reach the highest space density. We selected 29 radio-loud quasars at low radio frequencies (76 MHz). Their radio spectra, covering the range from 76 MHz to 5 GHz, are generally well reproduced by a single power law. We created samples that were matched in radio luminosity at lower redshift (from $z to $z to investigate any spectral evolution. We find that the fraction of flat-spectrum radio quasars (FSRQs) strongly increases with redshift (from $ 8$ at z=1.2 to $ 45$ at z$>$3.5). This effect is also observed in quasars with lower luminosities (down to $ The increase in the fraction of FSRQs with redshift corresponds to a decrease in the steep- spectrum radio quasars. This result can be explained when we assume that the beaming factor and the slope of the luminosity function do not change with redshift and if high-redshift radio-loud sources can be recognized as quasars only when they are seen at a small viewing angle ($ but most of them, about 90 are obscured in the UV and optical bands. We also found a trend for the size of radio sources to decrease with increasing redshift. Because projection effects are insufficient to cause this trend, we suggest that the large amount of gas causing the nuclear obscuration also hampers the growth of the more distant sources.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"55 12","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141689247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1051/0004-6361/202449720
S. Neha, A. Soam, G. Maheswar
We present an optical polarimetry study of the nearby star-forming region Lambda-Orionis to map the plane-of-the-sky magnetic field geometry to understand the magnetized evolution of the HII region and the associated small molecular clouds. We made multiwavelength polarization observations of 34 bright stars distributed across the region. We also present the R-band polarization measurements that focused on the small molecular clouds, bright-rimmed clouds (BRC), BRC 17, and BRC 18, which are located at the periphery of the HII region. The magnetic field lines exhibit a large-scale ordered orientation consistent with the Planck submillimeter polarization measurements. The magnetic field lines in the two BRCs are found to be roughly in north-south directions. However, a larger dispersion is noted in the orientation for BRC 17 compared to BRC 18. Using a structure-function analysis, we estimate the strength of the plane-of-the-sky component of the magnetic field as sim 28 mu G for BRC 17 and sim 40 mu G for BRC 18. The average dust grain size and the mean value of the total-to-selective extinction ratio (R$_ V $) in the HII region are found to be sim 0.51 pm 0.05 mu m and sim 2.9 pm 0.3, respectively. The distance of the whole HII region is estimated as sim 392 pm 8 pc by combining astrometry information from Global Astrometric Interferometer for Astrophysics (Gaia) early data release 3 (EDR3) for young stellar objects associated with BRCs and confirmed members of the central cluster Collinder 69.
我们对附近的恒星形成区 Lambda-Orionis 进行了光学偏振测量研究，以绘制天平面磁场几何图形，从而了解 HII 区域和相关小分子云的磁化演化。我们对分布在该区域的 34 颗明亮恒星进行了多波长偏振观测。我们还介绍了对位于 HII 区域外围的小分子云、亮边云（BRC）、BRC 17 和 BRC 18 进行的 R 波段偏振测量。磁场线呈现出与普朗克亚毫米波极化测量结果一致的大尺度有序方向。两个 BRC 中的磁场线大致呈南北走向。然而，与 BRC 18 相比，BRC 17 的方向有更大的离散性。通过结构函数分析，我们估计 BRC 17 的磁场天平面分量强度为 sim 28 mu G，BRC 18 为 sim 40 mu G。HII 区域的平均尘粒大小和总消光比（R$_ V $）的平均值分别为 sim 0.51 pm 0.05 mu m 和 sim 2.9 pm 0.3。结合天体物理学全球天体测量干涉仪（Gaia）早期数据第 3 版（EDR3）中与 BRCs 有关的年轻恒星天体的天体测量信息，以及中心星团 Collinder 69 的确认成员，估计整个 HII 区域的距离为 sim 392 pm 8 pc。
{"title":"Optical polarimetry study of the Lambda-Orionis star-forming region","authors":"S. Neha, A. Soam, G. Maheswar","doi":"10.1051/0004-6361/202449720","DOIUrl":"https://doi.org/10.1051/0004-6361/202449720","url":null,"abstract":"We present an optical polarimetry study of the nearby star-forming region Lambda-Orionis to map the plane-of-the-sky magnetic field geometry to understand the magnetized evolution of the HII region and the associated small molecular clouds. We made multiwavelength polarization observations of 34 bright stars distributed across the region. We also present the R-band polarization measurements that focused on the small molecular clouds, bright-rimmed clouds (BRC), BRC 17, and BRC 18, which are located at the periphery of the HII region. The magnetic field lines exhibit a large-scale ordered orientation consistent with the Planck submillimeter polarization measurements. The magnetic field lines in the two BRCs are found to be roughly in north-south directions. However, a larger dispersion is noted in the orientation for BRC 17 compared to BRC 18. Using a structure-function analysis, we estimate the strength of the plane-of-the-sky component of the magnetic field as sim 28 mu G for BRC 17 and sim 40 mu G for BRC 18. The average dust grain size and the mean value of the total-to-selective extinction ratio (R$_ V $) in the HII region are found to be sim 0.51 pm 0.05 mu m and sim 2.9 pm 0.3, respectively. The distance of the whole HII region is estimated as sim 392 pm 8 pc by combining astrometry information from Global Astrometric Interferometer for Astrophysics (Gaia) early data release 3 (EDR3) for young stellar objects associated with BRCs and confirmed members of the central cluster Collinder 69.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"57 11","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141338763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1051/0004-6361/202450095
Jake D. Turner, J. Grießmeier, P. Zarka, Xiang Zhang, E. Mauduit
o tis (tau Boo) exoplanetary system was tentatively detected using LOFAR (LOW-Frequency ARray) beamformed observations. If confirmed, this detection will be a major contribution to exoplanet science. However, follow-up observations are required to confirm this detection. Here, we present such follow-up observations of the tau Boo system using LOFAR. These observations cover 70$$ of the orbital period of tau Boo b including the orbital phases of the previous tentative detections. We used the BOREALIS pipeline to mitigate radio frequency interference and to search for bursty and slowly varying radio signals. BOREALIS was previously used to find the tentative radio signals from tau Boo. o tis exoplanetary system. o tis exoplanetary system.
o tis（tau Boo）系外行星系统是利用低频辐射计（LOFAR）波束形成的观测数据初步探测到的。如果得到证实，这次探测将是对系外行星科学的重大贡献。然而，要证实这一探测结果，还需要进行后续观测。在这里，我们将介绍利用LOFAR对木卫一系统进行的跟踪观测。这些观测覆盖了 "布谷头 "b 70$$$的轨道周期，包括之前暂定探测到的轨道阶段。我们使用 BOREALIS 管道来减轻射频干扰，并搜索突发和缓慢变化的射频信号。BOREALIS 之前曾被用来寻找来自布袋星的暂定射电信号。
{"title":"Follow-up LOFAR observations of the tau Boötis exoplanetary system","authors":"Jake D. Turner, J. Grießmeier, P. Zarka, Xiang Zhang, E. Mauduit","doi":"10.1051/0004-6361/202450095","DOIUrl":"https://doi.org/10.1051/0004-6361/202450095","url":null,"abstract":"o tis (tau Boo) exoplanetary system was tentatively detected using LOFAR (LOW-Frequency ARray) beamformed observations. If confirmed, this detection will be a major contribution to exoplanet science. However, follow-up observations are required to confirm this detection. Here, we present such follow-up observations of the tau Boo system using LOFAR. These observations cover 70$$ of the orbital period of tau Boo b including the orbital phases of the previous tentative detections. We used the BOREALIS pipeline to mitigate radio frequency interference and to search for bursty and slowly varying radio signals. BOREALIS was previously used to find the tentative radio signals from tau Boo. o tis exoplanetary system. o tis exoplanetary system.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"17 8","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141338817","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1051/0004-6361/202450364
W. Narloch, G. Hajdu, G. Pietrzyński, W. Gieren, B. Zgirski, P. Wielgórski, P. Karczmarek, M. Górski, D. Graczyk
RR Lyrae stars are excellent tracers of the old population II due to their period-luminosity (PL) and period-luminosity-metallicity (PLZ) relations. While these relations have been investigated in detail in many photometric bands, there are few comprehensive studies about them in Sloan-like systems. We present PL and PLZ relations (as well as their counterparts in Wesenheit magnitudes) in the Sloan--Pan-STARSS $g_ P1 r_ P1 i_ P1 $ bands obtained for Galactic RR Lyrae stars in the vincinity of the Sun. The data used in this paper were collected with the network of $40$ cm telescopes of the Las Cumbres Observatory, and geometric parallaxes were adopted from Gaia Data Release $3$. We derived PL and PLZ relations separately for RRab and RRc-type stars, as well as for the mixed population of RRab+RRc stars. To our knowledge, these are the first PL and PLZ relations in the Sloan bands determined using RR Lyrae stars in the Galactic field.
天琴座RR星由于其周期-光度（PL）和周期-光度-金属性（PLZ）关系而成为旧种群II的极佳追踪者。虽然这些关系在许多测光波段中都得到了详细研究，但在类似 Sloan 系统中却很少有全面的研究。我们介绍了在Sloan--Pan--STARSS $g_ P1 r_ P1 i_ P1 $波段中太阳附近银河RR天琴座恒星的PL和PLZ关系（及其对应的Wesenheit星等）。本文使用的数据是由拉斯坎布雷斯天文台的 40$ cm 望远镜网络收集的，几何视差采用的是 Gaia Data Release 3$ 的数据。我们分别推导出了RRab和RRc型恒星以及RRab+RRc混合型恒星的PL和PLZ关系。据我们所知，这是首次利用银河系星域中的天琴座RR星确定斯隆波段的PL和PLZ关系。
{"title":"Period-luminosity and period-luminosity-metallicity relations for Galactic RR Lyrae stars in the Sloan bands","authors":"W. Narloch, G. Hajdu, G. Pietrzyński, W. Gieren, B. Zgirski, P. Wielgórski, P. Karczmarek, M. Górski, D. Graczyk","doi":"10.1051/0004-6361/202450364","DOIUrl":"https://doi.org/10.1051/0004-6361/202450364","url":null,"abstract":"RR Lyrae stars are excellent tracers of the old population II \u0000 due to their period-luminosity \u0000 (PL) and period-luminosity-metallicity (PLZ) relations. While these relations have been investigated\u0000 in detail in many photometric bands, there are few comprehensive studies about them in Sloan-like \u0000 systems. We present PL and PLZ relations \u0000 (as well as their counterparts in Wesenheit magnitudes) in the Sloan--Pan-STARSS \u0000 $g_ P1 r_ P1 i_ P1 $ bands obtained for Galactic RR Lyrae stars in the vincinity of the Sun. The data used in this paper were collected with the network of $40$ cm telescopes of the \u0000 Las Cumbres Observatory, and geometric parallaxes were adopted from Gaia Data Release $3$. We derived PL and PLZ relations separately for RRab and RRc-type stars, as well as for the \u0000 mixed population of RRab+RRc stars. To our knowledge, these are the first PL and PLZ relations in the Sloan bands determined \u0000 using RR Lyrae stars in the Galactic field.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"47 10","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141343810","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1051/0004-6361/202449479
C. Ferrari
Most analyses of the infrared emission of Saturn's rings and icy satellites have considered pure water ice as the constituent of regolith and particle surfaces. Visual and near-infrared observations have shown, however, that darkening and reddening contaminants are present at a fraction level of a few percent. In the spectral domain 10-2000 $ cm^ $, water ice becomes transparent in a few windows, which in particular causes the roll-off of emissivity of icy surfaces that is observed below 50 $ cm^ $. Their emissivity there may be affected by these contaminants. We present a quantitative global sensitivity analysis of a hybrid Mie-Hapke model to evaluate the influence of regolith properties and contaminant fraction on the infrared emissivity of icy rings or moons over this spectral range. A hybrid Mie-Hapke model of the hemispherical emissivity $ was made, including various diffraction correction and mixing types with tholins or amorphous carbon grains, or grain size distributions and some anisotropy in emission. A Sobol global sensitivity analysis provided quantitative levels of importance for these factors versus wave number $w_n$. Given the a priori uncertainties, the most important factor acting on $ remains the size distribution of regolith grains and the average anisotropy factor xi . For $w_n$> 50 $ cm^ $, xi , the power-law index $p$ and the minimum $a_ min $ of the size distribution are most influential. In windows of water-ice transparency (10-50, 300-600, and 900-1300 $ cm^ $), the emissivity is also sensitive, but to a lesser extent, to the maximum grain size $a_ max $ and the fraction $f$ of contaminants, if mixed at the molecular level. This model provides a self-consistent tool for interpreting multi-modal observations of the thermal emission from icy surfaces. It also offers interesting insights into recent mid-infrared observations of Saturn's rings and Jupiter's moon Ganymede by the JWST-MIRI instrument.
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Pub Date : 2024-06-14DOI: 10.1051/0004-6361/202450590
G. Paraschos, M. Wielgus, P. Benke, V. Mpisketzis, F. Rösch, K. Dasyra, E. Ros, M. Kadler, R. Ojha, P. G. Edwards, L. Hyland, J. Quick, S. Weston
Radio galaxies harbouring jetted active galactic nuclei are a frequent target of very-long-baseline interferometry (VLBI) because they play an essential role in exploring how jets form and propagate. Hence, only few have not been detected with VLBI yet; is one of the most famous examples. Here we present the first detection of the compact core region of with VLBI. At 8.4,GHz the faint core is consistent with an unresolved point source. We constrained its flux density to be $S_0= and its diameter to be $D_0^ min The high values of the measured brightness temperature ($T_ B K $) imply that the observed radiation is of non-thermal origin, likely associated with the synchrotron emission from the active galactic nucleus. We also investigated the possibility of a second radio source being present within the field of view. Adding a second Gaussian component to the geometrical model-fit does not significantly improve the quality of the fit and we, therefore, conclude that our detection corresponds to the compact core of Analysis of the non-trivial closure phases provides evidence for the detection of more extended flux density, on the angular scale of $ Finally, the fractional circular polarisation of the core is consistent with zero, with a conservative upper limit being $m_ circ
存在喷流活动星系核的射电星系是甚长基线干涉测量（VLBI）的一个常见目标，因为它们在探索喷流如何形成和传播方面起着至关重要的作用。在这里，我们首次用VLBI探测到了紧凑核心区。在8.4（,GHz）频率下，这个暗核与一个未分辨的点源是一致的。我们把它的通量密度限制在$S_0=，直径限制在$D_0^min。测量到的亮度温度（$T_ B K $）的高值意味着观测到的辐射是非热源的，很可能与活动星系核的同步辐射有关。在几何模型拟合中加入第二个高斯分量并不能明显改善拟合的质量，因此我们得出结论，我们的探测结果对应于银河系核的紧凑内核。
{"title":"First very long baseline interferometry detection of FornaxA","authors":"G. Paraschos, M. Wielgus, P. Benke, V. Mpisketzis, F. Rösch, K. Dasyra, E. Ros, M. Kadler, R. Ojha, P. G. Edwards, L. Hyland, J. Quick, S. Weston","doi":"10.1051/0004-6361/202450590","DOIUrl":"https://doi.org/10.1051/0004-6361/202450590","url":null,"abstract":"Radio galaxies harbouring jetted active galactic nuclei are a frequent target of very-long-baseline interferometry (VLBI) because they play an essential role in exploring how jets form and propagate.\u0000Hence, only few have not been detected with VLBI yet; is one of the most famous examples. Here we present the first detection of the compact core region of with VLBI. At 8.4,GHz the faint core is consistent with an unresolved point source. We constrained its flux density to be $S_0= and its diameter to be $D_0^ min The high values of the measured brightness temperature ($T_ B K $) imply that the observed radiation is of non-thermal origin, likely associated with the synchrotron emission from the active galactic nucleus.\u0000We also investigated the possibility of a second radio source being present within the field of view.\u0000Adding a second Gaussian component to the geometrical model-fit does not significantly improve the quality of the fit and we, therefore, conclude that our detection corresponds to the compact core of Analysis of the non-trivial closure phases provides evidence for the detection of more extended flux density, on the angular scale of $ Finally, the fractional circular polarisation of the core is consistent with zero, with a conservative upper limit being $m_ circ","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"31 36","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141340489","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1051/0004-6361/202347972
Hailiang Shen, J. Esimbek, C. Henkel, Ye Xu, Jianjun Zhou, Da-lei Li, Yuxin He, Xindi Tang, Gang Wu, T. Komesh, K. Tursun, Dongdong Zhou, Ernar Imanaly., Dilda Berdikhan.
The feedback effect of massive stars can either accelerate or inhibit star formation activity within molecular clouds. Studying the morphology of molecular clouds near W5 offers an excellent opportunity to examine this feedback effect. We conducted a comprehensive survey of the W5 complex using the Purple Mountain Observatory 13.7,m millimeter telescope. This survey includes 12CO, 13CO, and C18O ($J$ = 1--0), with a sky coverage of 6.6 $ deg^2$ circ l circ circ b circ $). Furthermore, we performed simultaneous observations of the NH$_3$ (1,1) and NH$_3$ (2,2) lines in the four densest star-forming regions of W5, using the 26,m radio telescope of the Xinjiang Astronomy Observatory (XAO). Our analysis of the morphological distribution of the molecular clouds, distribution of high-mass young stellar objects (HMYSOs), 13CO/C18O abundance ratio, and the stacked average spectral line distribution at different 8mu m thresholds provide compelling evidence of triggering. Within the mapped region, we identified a total of 212 molecular clumps in the 13CO cube data using the astrodendro algorithm. Remarkably, approximately 26.4$$ (56) of these clumps demonstrate the potential to form massive stars and 42.9$$ (91) of them are gravitationally bound. Within clumps that are capable of forming high-mass stars, there is a distribution of class,I YSOs, all located in dense regions near the boundaries of the ii regions. The detection of NH$_3$ near the most prominent cores reveals moderate kinetic temperatures and densities (as CO). Comparing the $T_ kin $ and $T_ ex $ values reveals a reversal in trends for AFGL,4029 (higher ex $ and lower $T_ kin $) and W5-w1, indicating the inadequacy of optically thick CO for dense region parameter calculations. Moreover, a comparison of the intensity distributions between NH$_3$ (1,1) and C18O (1-0) in the four densest region reveals a notable depletion effect in AFGL,4029, characterised by a low kin $ (9,K) value and a relatively high NH$_3$ column density, 2.5times $. By classifying the 13CO clumps as: "feedback," "non-feedback," "outflow," or "non-outflow" clumps, we observe that the parameters of the "feedback" and "outflow" clumps exhibit variations based on the intensity of the internal 8mu m flux and the outflow energy, respectively. These changes demonstrate a clear linear correlation, which distinctly separate them from the parameter distributions of the "non-feedback" and "non-outflow" clumps, thus providing robust evidence to support a triggering scenario.
大质量恒星的反馈效应可以加速或抑制分子云中的恒星形成活动。研究W5附近分子云的形态为研究这种反馈效应提供了一个极好的机会。我们利用紫金山天文台的13.7（m）毫米望远镜对W5复合体进行了一次全面巡天。这次巡天包括 12CO、13CO 和 C18O ($J$ = 1--0)，天空覆盖范围为 6.6 $ deg^2$ circ l circ b circ $)。此外，我们还利用新疆天文台的26,m射电望远镜对W5的四个最密集恒星形成区的NH$_3$ (1,1)和NH$_3$ (2,2)线进行了同步观测。我们对分子云的形态分布、高质年轻恒星天体（HMYSO）的分布、13CO/C18O丰度比以及不同8mu m阈值下的叠加平均谱线分布的分析为触发提供了有力的证据。在绘制的区域内，我们利用 astrodendro 算法在 13CO 立方数据中总共识别出 212 个分子团块。值得注意的是，这些团块中大约有 26.4$$（56 个）具有形成大质量恒星的潜力，其中 42.9$$（91 个）具有引力束缚。在能够形成大质量恒星的星团内部，分布着class/,I YSOs，它们都位于ii区边界附近的致密区域。在最突出的核心附近探测到的 NH$_3$ 揭示了中等的动力学温度和密度（与 CO 一样）。比较 $T_ kin $ 和 $T_ ex $ 的值发现，AFGL,4029（较高的 ex $ 和较低的 $T_ kin $）和 W5-w1 的趋势相反，这表明光厚 CO 在致密区参数计算中的不足。此外，通过比较四个最致密区域中 NH$_3$ (1,1) 和 C18O (1-0) 的强度分布，发现 AFGL,4029 中存在明显的耗竭效应，其特征是 kin $ (9,K) 值较低，而 NH$_3$ 柱密度相对较高，为 2.5 倍 $。通过将13CO团块分类为"反馈"、"非反馈"、"外流 "或 "非外流 "团块，我们观察到 "反馈 "和 "外流 "团块的参数分别根据内部 8mu m 流量和外流能量的强度而变化。这些变化呈现出明显的线性相关，与 "非反馈 "和 "非外流 "团块的参数分布截然不同，从而为支持触发情景提供了有力的证据。
{"title":"Extended CO(1-0) survey and ammonia measurements towards two bubble regions in W5. Feedback on molecular gas and clumps","authors":"Hailiang Shen, J. Esimbek, C. Henkel, Ye Xu, Jianjun Zhou, Da-lei Li, Yuxin He, Xindi Tang, Gang Wu, T. Komesh, K. Tursun, Dongdong Zhou, Ernar Imanaly., Dilda Berdikhan.","doi":"10.1051/0004-6361/202347972","DOIUrl":"https://doi.org/10.1051/0004-6361/202347972","url":null,"abstract":"The feedback effect of massive stars can either accelerate or inhibit star formation activity within molecular clouds. Studying the morphology of molecular clouds near W5 offers an excellent opportunity to examine this feedback effect. We conducted a comprehensive survey of the W5 complex using the Purple Mountain Observatory 13.7,m millimeter telescope. This survey includes 12CO, 13CO, and C18O ($J$ = 1--0), with a sky coverage of 6.6 $ deg^2$ circ l circ circ b circ $). Furthermore, we performed simultaneous observations of the NH$_3$ (1,1) and NH$_3$ (2,2) lines in the four densest star-forming regions of W5, using the 26,m radio telescope of the Xinjiang Astronomy Observatory (XAO). Our analysis of the morphological distribution of the molecular clouds, distribution of high-mass young stellar objects (HMYSOs), 13CO/C18O abundance ratio, and the stacked average spectral line distribution at different 8mu m thresholds provide compelling evidence of triggering. Within the mapped region, we identified a total of 212 molecular clumps in the 13CO cube data using the astrodendro algorithm. Remarkably, approximately 26.4$$ (56) of these clumps demonstrate the potential to form massive stars and 42.9$$ (91) of them are gravitationally bound. Within clumps that are capable of forming high-mass stars, there is a distribution of class,I YSOs, all located in dense regions near the boundaries of the ii regions. The detection of NH$_3$ near the most prominent cores reveals moderate kinetic temperatures and densities (as CO). Comparing the $T_ kin $ and $T_ ex $ values reveals a reversal in trends for AFGL,4029 (higher ex $ and lower $T_ kin $) and W5-w1, indicating the inadequacy of optically thick CO for dense region parameter calculations. Moreover, a comparison of the intensity distributions between NH$_3$ (1,1) and C18O (1-0) in the four densest region reveals a notable depletion effect in AFGL,4029, characterised by a low kin $ (9,K) value and a relatively high NH$_3$ column density, 2.5times $. By classifying the 13CO clumps as: \"feedback,\" \"non-feedback,\" \"outflow,\" or \"non-outflow\" clumps, we observe that the parameters of the \"feedback\" and \"outflow\" clumps exhibit variations based on the intensity of the internal 8mu m flux and the outflow energy, respectively. These changes demonstrate a clear linear correlation, which distinctly separate them from the parameter distributions of the \"non-feedback\" and \"non-outflow\" clumps, thus providing robust evidence to support a triggering scenario.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"43 38","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141339881","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-06-14DOI: 10.1051/0004-6361/202347824
Jonas Zbinden, L. Kleint, Brandon Panos
Context : Reliably predicting solar flares can mitigate the risks of technological damage and enhance scientific output by providing reliable pointings for observational campaigns. Flare precursors in the spectral line Mg ii have been identified. Aims : We extend previous studies by examining the presence of flare precursors in additional spectral lines, such as Si iv and C ii over longer time windows, and for more observations. Methods : We trained neural networks and XGBoost decision trees to distinguish spectra observed from active regions that lead to a flare and those that did not. To enhance the information within each observation, we tested different masking methods to preprocess the data. Results : We find average classification true skill statistics (TSS) scores of $0.53$ for Mg ii $0.44$ for Si iv and $0.42$ for C ii . We speculate that Mg ii h k performs best because it samples the highest formation height range, and is sensitive to heating and density changes in the mid- to upper chromosphere. The flaring area relative to the field of view has a large effect on the model classification score and needs to be accounted for. Combining spectral lines has proven difficult, due to the difference in areas of high probability for an imminent flare between different lines. Conclusion : Our models extract information from all three lines, independent of observational bias or GOES X-ray flux precursors, implying that the physics encoded in a combination of high resolution spectral data could be useful for flare forecasting.
背景：可靠地预测太阳耀斑可以减轻技术损害的风险，并为观测活动提供可靠的指向，从而提高科学产出。已经确定了光谱线 Mg ii 中的耀斑前兆。目的 ：我们扩展了以前的研究，在更长的时间窗口和更多的观测中，研究了其他光谱线（如 Si iv 和 C ii）中是否存在耀斑前兆。方法：我们训练了神经网络和 XGBoost 决策树，以区分从活动区观测到的导致耀斑和不导致耀斑的光谱。为了增强每个观测数据的信息量，我们测试了不同的掩蔽方法来预处理数据。结果：我们发现镁 ii 的平均分类真实技能统计分数为 0.53 美元，硅 iv 为 0.44 美元，C ii 为 0.42 美元。我们推测 Mg ii h k 的表现最好，因为它采样了最高的形成高度范围，而且对中高层色球层的加热和密度变化很敏感。相对于视场的耀斑区域对模型分类得分有很大影响，需要加以考虑。由于不同的光谱线在即将发生耀斑的高概率区域存在差异，因此合并光谱线被证明是很困难的。结论 ：我们的模型从所有三条谱线中提取信息，不受观测偏差或 GOES X 射线通量前兆的影响，这意味着高分辨率光谱数据组合中的物理编码可能对耀斑预报有用。
{"title":"Investigating and comparing the IRIS spectral lines Mg ii, Si iv, or C ii for flare precursor diagnostics","authors":"Jonas Zbinden, L. Kleint, Brandon Panos","doi":"10.1051/0004-6361/202347824","DOIUrl":"https://doi.org/10.1051/0004-6361/202347824","url":null,"abstract":"Context : Reliably predicting solar flares can mitigate the risks of technological damage and enhance scientific output by providing reliable pointings for observational campaigns. Flare precursors in the spectral line Mg ii have been identified. Aims : We extend previous studies by examining the presence of flare precursors in additional spectral lines, such as Si iv and C ii over longer time windows, and for more observations. Methods : We trained neural networks and XGBoost decision trees to distinguish spectra observed from active regions that lead to a flare and those that did not. To enhance the information within each observation, we tested different masking methods to preprocess the data. Results : We find average classification true skill statistics (TSS) scores of $0.53$ for Mg ii $0.44$ for Si iv and $0.42$ for C ii . We speculate that Mg ii h k performs best because it samples the highest formation height range, and is sensitive to heating and density changes in the mid- to upper chromosphere. The flaring area relative to the field of view has a large effect on the model classification score and needs to be accounted for. Combining spectral lines has proven difficult, due to the difference in areas of high probability for an imminent flare between different lines. Conclusion : Our models extract information from all three lines, independent of observational bias or GOES X-ray flux precursors, implying that the physics encoded in a combination of high resolution spectral data could be useful for flare forecasting.","PeriodicalId":505693,"journal":{"name":"Astronomy & Astrophysics","volume":"45 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141338717","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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