Pub Date : 2023-10-01DOI: 10.3847/2041-8213/acfdab
Jon K. Zink, Andrew W. Howard
Abstract This study considers the characteristics of planetary systems with giant planets based on a population-level analysis of the California Legacy Survey planet catalog. We identified three characteristics common to hot Jupiters (HJs). First, while not all HJs have a detected outer giant planet companion ( Msini=0.3–30MJup ), such companions are ubiquitous when survey completeness corrections are applied for orbital periods out to 40,000 days. Giant-harboring systems without an HJ also host at least one outer giant planet companion per system. Second, the mass distributions of HJs and other giant planets are indistinguishable. However, within a planetary system that includes an HJ, the outer giant planet companions are at least 3× more massive than the inner HJs. Third, the eccentricity distribution of the outer companions in HJ systems (with an average model eccentricity of 〈 e 〉 = 0.34 ± 0.05) is different from the corresponding outer planets in planetary systems without HJs (〈 e 〉 = 0.19 ± 0.02). We conclude that the existence of two gas giants, where the outermost planet has an eccentricity ≥0.2 and is 3× more massive, are key factors in the production of an HJ. Our simple model based on these factors predicts that ∼10% of warm and cold Jupiter systems will by chance meet these assembly criteria, which is consistent with our measurement of a 16% ± 6% relative occurrence of HJ systems to all giant-harboring systems. We find that these three features favor coplanar high-eccentricity migration as the dominant mechanism for HJ formation.
本研究基于加州遗产调查行星目录的人口水平分析，考虑了具有巨行星的行星系统的特征。我们确定了热木星(HJs)的三个共同特征。首先，虽然不是所有的HJs都有一个被探测到的外行星伴星(msini = 0.3 - 30mjup)，但当对40000天的轨道周期进行巡天完整性校正时，这样的伴星是无处不在的。没有HJ的巨行星庇护系统也至少有一个外部巨行星伴星。其次，HJs和其他巨行星的质量分布难以区分。然而，在一个包含HJ的行星系统中，外部的巨行星伴星至少比内部的HJ大3倍。第三，HJ系统外伴行星的偏心率分布(平均模型偏心率< e > = 0.34±0.05)与不含HJ的行星系统外伴行星的偏心率分布(< e > = 0.19±0.02)不同。我们得出结论，两颗气体巨星的存在是形成HJ的关键因素，其中最外层行星的离心率≥0.2，质量是HJ的3倍。我们基于这些因素的简单模型预测，约10%的温暖和寒冷木星系统将偶然满足这些组合标准，这与我们测量的HJ系统相对于所有巨行星系统的16%±6%的相对发生率是一致的。研究发现，这三个特征有利于共面高偏心运移成为HJ形成的主要机制。
{"title":"Hot Jupiters Have Giant Companions: Evidence for Coplanar High-eccentricity Migration","authors":"Jon K. Zink, Andrew W. Howard","doi":"10.3847/2041-8213/acfdab","DOIUrl":"https://doi.org/10.3847/2041-8213/acfdab","url":null,"abstract":"Abstract This study considers the characteristics of planetary systems with giant planets based on a population-level analysis of the California Legacy Survey planet catalog. We identified three characteristics common to hot Jupiters (HJs). First, while not all HJs have a detected outer giant planet companion ( <?CDATA $Msin i=0.3mbox{--}30,{M}_{mathrm{Jup}}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:mi>M</mml:mi> <mml:mi>sin</mml:mi> <mml:mi>i</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.3</mml:mn> <mml:mo>–</mml:mo> <mml:mn>30</mml:mn> <mml:mspace width=\"0.25em\" /> <mml:msub> <mml:mrow> <mml:mi>M</mml:mi> </mml:mrow> <mml:mrow> <mml:mi>Jup</mml:mi> </mml:mrow> </mml:msub> </mml:math> ), such companions are ubiquitous when survey completeness corrections are applied for orbital periods out to 40,000 days. Giant-harboring systems without an HJ also host at least one outer giant planet companion per system. Second, the mass distributions of HJs and other giant planets are indistinguishable. However, within a planetary system that includes an HJ, the outer giant planet companions are at least 3× more massive than the inner HJs. Third, the eccentricity distribution of the outer companions in HJ systems (with an average model eccentricity of 〈 e 〉 = 0.34 ± 0.05) is different from the corresponding outer planets in planetary systems without HJs (〈 e 〉 = 0.19 ± 0.02). We conclude that the existence of two gas giants, where the outermost planet has an eccentricity ≥0.2 and is 3× more massive, are key factors in the production of an HJ. Our simple model based on these factors predicts that ∼10% of warm and cold Jupiter systems will by chance meet these assembly criteria, which is consistent with our measurement of a 16% ± 6% relative occurrence of HJ systems to all giant-harboring systems. We find that these three features favor coplanar high-eccentricity migration as the dominant mechanism for HJ formation.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"180 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135760295","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acfcad
Oliver J. Roberts, Matthew G. Baring, Daniela Huppenkothen, Chryssa Kouveliotou, Ersin Göğüş, Yuki Kaneko, Lin Lin, Alexander J. van der Horst, George Younes
Abstract Magnetars are young neutron stars powered by the strongest magnetic fields in the Universe (10 13–15 G). Their transient X-ray emission usually manifests as short (a few hundred milliseconds), bright, energetic (∼10 40–41 erg) X-ray bursts. Since its discovery in 2014, SGR J1935+2154 has become one of the most prolific magnetars, exhibiting very active bursting episodes and other fascinating events, such as pulse timing antiglitches and fast radio bursts. Here we present evidence for possible 42 Hz (24 ms) quasiperiodic oscillations in the ν F ν spectrum peak energy ( E p ) identified in a unique burst detected with the Fermi Gamma-ray Burst Monitor in 2022 January. While quasiperiodic oscillations have been previously reported in the intensity of magnetar burst light curves, quasiperiodic oscillations in E p have not. We also find an additional event from the same outburst that appears to exhibit a similar character in E p , albeit of lower statistical quality. For these two exceptional transients, such E p oscillations can be explained by magnetospheric density and pressure perturbations. For burst-emitting plasma consisting purely of e + e − pairs, these acoustic modes propagate along a highly magnetized flux tube of length up to around L ∼ 130 neutron star radii, with L being lower if ions are present in the emission zone. Detailed time-resolved analyses of other magnetar bursts are encouraged to evaluate the rarity of these events and their underlying mechanisms.
{"title":"Quasiperiodic Peak Energy Oscillations in X-Ray Bursts from SGR J1935+2154","authors":"Oliver J. Roberts, Matthew G. Baring, Daniela Huppenkothen, Chryssa Kouveliotou, Ersin Göğüş, Yuki Kaneko, Lin Lin, Alexander J. van der Horst, George Younes","doi":"10.3847/2041-8213/acfcad","DOIUrl":"https://doi.org/10.3847/2041-8213/acfcad","url":null,"abstract":"Abstract Magnetars are young neutron stars powered by the strongest magnetic fields in the Universe (10 13–15 G). Their transient X-ray emission usually manifests as short (a few hundred milliseconds), bright, energetic (∼10 40–41 erg) X-ray bursts. Since its discovery in 2014, SGR J1935+2154 has become one of the most prolific magnetars, exhibiting very active bursting episodes and other fascinating events, such as pulse timing antiglitches and fast radio bursts. Here we present evidence for possible 42 Hz (24 ms) quasiperiodic oscillations in the ν F ν spectrum peak energy ( E p ) identified in a unique burst detected with the Fermi Gamma-ray Burst Monitor in 2022 January. While quasiperiodic oscillations have been previously reported in the intensity of magnetar burst light curves, quasiperiodic oscillations in E p have not. We also find an additional event from the same outburst that appears to exhibit a similar character in E p , albeit of lower statistical quality. For these two exceptional transients, such E p oscillations can be explained by magnetospheric density and pressure perturbations. For burst-emitting plasma consisting purely of e + e − pairs, these acoustic modes propagate along a highly magnetized flux tube of length up to around L ∼ 130 neutron star radii, with L being lower if ions are present in the emission zone. Detailed time-resolved analyses of other magnetar bursts are encouraged to evaluate the rarity of these events and their underlying mechanisms.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"13 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135761226","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acfe71
Luis A. Zapata, Manuel Fernández-López, Silvia Leurini, Estrella Guzmán Ccolque, Skretas, I. M., Luis F. Rodríguez, Aina, Palau, Karl M. Menten, Friedrich, Wyrowski
Abstract In the last years there has been a substantial increase in the number of the reported massive and luminous star-forming regions with related explosive outflows thanks to the superb sensitivity and angular resolution provided by the new radio, infrared, and optical facilities. Here, we report one more explosive outflow related with the massive and bright star-forming region IRAS 12326−6245 using Band 6 sensitive and high-angular-resolution (∼0.″2) Atacama Large Millimeter/Submillimeter Array observations. We find over 10 molecular and collimated well-defined streamers, with Hubble–Lemaitre–like expansion motions, and pointing right to the center of a dusty and molecular shell (reported for the first time here) localized in the northern part of the UC H ii region known as G301.1A. The estimated kinematic age and energy for the explosion are ∼700 yr and 10 48 erg, respectively. Taking into account the recently reported explosive outflows together with IRAS 12326−6245, we estimate an event rate of once every 90 yr in our Galaxy, similar to the formation rate of massive stars.
{"title":"One, Two, Three ... An Explosive Outflow in IRAS 12326-6245 Revealed by ALMA","authors":"Luis A. Zapata, Manuel Fernández-López, Silvia Leurini, Estrella Guzmán Ccolque, Skretas, I. M., Luis F. Rodríguez, Aina, Palau, Karl M. Menten, Friedrich, Wyrowski","doi":"10.3847/2041-8213/acfe71","DOIUrl":"https://doi.org/10.3847/2041-8213/acfe71","url":null,"abstract":"Abstract In the last years there has been a substantial increase in the number of the reported massive and luminous star-forming regions with related explosive outflows thanks to the superb sensitivity and angular resolution provided by the new radio, infrared, and optical facilities. Here, we report one more explosive outflow related with the massive and bright star-forming region IRAS 12326−6245 using Band 6 sensitive and high-angular-resolution (∼0.″2) Atacama Large Millimeter/Submillimeter Array observations. We find over 10 molecular and collimated well-defined streamers, with Hubble–Lemaitre–like expansion motions, and pointing right to the center of a dusty and molecular shell (reported for the first time here) localized in the northern part of the UC H ii region known as G301.1A. The estimated kinematic age and energy for the explosion are ∼700 yr and 10 48 erg, respectively. Taking into account the recently reported explosive outflows together with IRAS 12326−6245, we estimate an event rate of once every 90 yr in our Galaxy, similar to the formation rate of massive stars.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135762041","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acfdae
Elias R. Most, Alexander A. Philippov
Abstract The presence of magnetic fields in the late inspiral of black hole–neutron star binaries could lead to potentially detectable electromagnetic precursor transients. Using general-relativistic force-free electrodynamics simulations, we investigate premerger interactions of the common magnetosphere of black hole–neutron star systems. We demonstrate that these systems can feature copious electromagnetic flaring activity, which we find depends on the magnetic field orientation but not on black hole spin. Due to interactions with the surrounding magnetosphere, these flares could lead to fast-radio-burst-like transients and X-ray emission, with EM≲1041B*/1012G2ergs−1 as an upper bound on the luminosity, where B * is the magnetic field strength on the surface of the neutron star.
在黑洞-中子星双星的后期吸气中磁场的存在可能导致潜在的可探测的电磁前体瞬变。利用广义相对论的无力电动力学模拟，我们研究了黑洞-中子星系统共同磁层的合并前相互作用。我们证明了这些系统可以具有丰富的电磁耀斑活动，我们发现这取决于磁场方向，而不是黑洞自旋。由于与周围磁层的相互作用，这些耀斑可能导致类似快速射电暴的瞬态和x射线发射，亮度的上限为EM > 10 41 B * / 10 12 G 2 erg s−1，其中B *是中子星表面的磁场强度。
{"title":"Electromagnetic Precursors to Black Hole–Neutron Star Gravitational Wave Events: Flares and Reconnection-powered Fast Radio Transients from the Late Inspiral","authors":"Elias R. Most, Alexander A. Philippov","doi":"10.3847/2041-8213/acfdae","DOIUrl":"https://doi.org/10.3847/2041-8213/acfdae","url":null,"abstract":"Abstract The presence of magnetic fields in the late inspiral of black hole–neutron star binaries could lead to potentially detectable electromagnetic precursor transients. Using general-relativistic force-free electrodynamics simulations, we investigate premerger interactions of the common magnetosphere of black hole–neutron star systems. We demonstrate that these systems can feature copious electromagnetic flaring activity, which we find depends on the magnetic field orientation but not on black hole spin. Due to interactions with the surrounding magnetosphere, these flares could lead to fast-radio-burst-like transients and X-ray emission, with <?CDATA ${{ mathcal L }}_{mathrm{EM}}lesssim {10}^{41}{left({B}_{* }/{10}^{12},{rm{G}}right)}^{2},mathrm{erg},{{rm{s}}}^{-1}$?> <mml:math xmlns:mml=\"http://www.w3.org/1998/Math/MathML\" overflow=\"scroll\"> <mml:msub> <mml:mrow> <mml:mi mathvariant=\"italic\"></mml:mi> </mml:mrow> <mml:mrow> <mml:mi>EM</mml:mi> </mml:mrow> </mml:msub> <mml:mo>≲</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>41</mml:mn> </mml:mrow> </mml:msup> <mml:msup> <mml:mrow> <mml:mfenced close=\")\" open=\"(\"> <mml:mrow> <mml:msub> <mml:mrow> <mml:mi>B</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>*</mml:mo> </mml:mrow> </mml:msub> <mml:mrow> <mml:mo stretchy=\"true\">/</mml:mo> </mml:mrow> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>12</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width=\"0.25em\" /> <mml:mi mathvariant=\"normal\">G</mml:mi> </mml:mrow> </mml:mfenced> </mml:mrow> <mml:mrow> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> <mml:mspace width=\"0.25em\" /> <mml:mi>erg</mml:mi> <mml:mspace width=\"0.25em\" /> <mml:msup> <mml:mrow> <mml:mi mathvariant=\"normal\">s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:math> as an upper bound on the luminosity, where B * is the magnetic field strength on the surface of the neutron star.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"196 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135762861","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acf769
Adam G. Riess, Gagandeep S. Anand, Wenlong Yuan, Stefano Casertano, Andrew Dolphin, Lucas M. Macri, Louise Breuval, Dan Scolnic, Marshall Perrin, Richard I. Anderson
Abstract High-resolution James Webb Space Telescope (JWST) observations can test confusion-limited Hubble Space Telescope (HST) observations for a photometric bias that could affect extragalactic Cepheids and the determination of the Hubble constant. We present JWST NIRCAM observations in two epochs and three filters of >320 Cepheids in NGC 4258 (which has a 1.5% maser-based geometric distance) and in NGC 5584 (host of SN Ia 2007af), near the median distance of the SH0ES HST SN Ia host sample and with the best leverage among them to detect such a bias. JWST provides far superior source separation from line-of-sight companions than HST in the near-infrared to largely negate confusion or crowding noise at these wavelengths, where extinction is minimal. The result is a remarkable >2.5× reduction in the dispersion of the Cepheid period–luminosity relations, from 0.45 to 0.17 mag, improving individual Cepheid precision from 20% to 7%. Two-epoch photometry confirmed identifications, tested JWST photometric stability, and constrained Cepheid phases. The P – L relation intercepts are in very good agreement, with differences (JWST−HST) of 0.00 ± 0.03 and 0.02 ± 0.03 mag for NGC 4258 and NGC 5584, respectively. The difference in the determination of H 0 between HST and JWST from these intercepts is 0.02 ± 0.04 mag, insensitive to JWST zero-points or count rate nonlinearity thanks to error cancellation between rungs. We explore a broad range of analysis variants (including passband combinations, phase corrections, measured detector offsets, and crowding levels) indicating robust baseline results. These observations provide the strongest evidence yet that systematic errors in HST Cepheid photometry do not play a significant role in the present Hubble Tension. Upcoming JWST observations of >12 SN Ia hosts should further refine the local measurement of the Hubble constant.
{"title":"Crowded No More: The Accuracy of the Hubble Constant Tested with High-resolution Observations of Cepheids by JWST","authors":"Adam G. Riess, Gagandeep S. Anand, Wenlong Yuan, Stefano Casertano, Andrew Dolphin, Lucas M. Macri, Louise Breuval, Dan Scolnic, Marshall Perrin, Richard I. Anderson","doi":"10.3847/2041-8213/acf769","DOIUrl":"https://doi.org/10.3847/2041-8213/acf769","url":null,"abstract":"Abstract High-resolution James Webb Space Telescope (JWST) observations can test confusion-limited Hubble Space Telescope (HST) observations for a photometric bias that could affect extragalactic Cepheids and the determination of the Hubble constant. We present JWST NIRCAM observations in two epochs and three filters of >320 Cepheids in NGC 4258 (which has a 1.5% maser-based geometric distance) and in NGC 5584 (host of SN Ia 2007af), near the median distance of the SH0ES HST SN Ia host sample and with the best leverage among them to detect such a bias. JWST provides far superior source separation from line-of-sight companions than HST in the near-infrared to largely negate confusion or crowding noise at these wavelengths, where extinction is minimal. The result is a remarkable >2.5× reduction in the dispersion of the Cepheid period–luminosity relations, from 0.45 to 0.17 mag, improving individual Cepheid precision from 20% to 7%. Two-epoch photometry confirmed identifications, tested JWST photometric stability, and constrained Cepheid phases. The P – L relation intercepts are in very good agreement, with differences (JWST−HST) of 0.00 ± 0.03 and 0.02 ± 0.03 mag for NGC 4258 and NGC 5584, respectively. The difference in the determination of H 0 between HST and JWST from these intercepts is 0.02 ± 0.04 mag, insensitive to JWST zero-points or count rate nonlinearity thanks to error cancellation between rungs. We explore a broad range of analysis variants (including passband combinations, phase corrections, measured detector offsets, and crowding levels) indicating robust baseline results. These observations provide the strongest evidence yet that systematic errors in HST Cepheid photometry do not play a significant role in the present Hubble Tension. Upcoming JWST observations of >12 SN Ia hosts should further refine the local measurement of the Hubble constant.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135810074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acff5e
Fabio Pacucci, Yueying Ni, Abraham Loeb
Abstract A recent study found dynamical evidence of a supermassive black hole of ∼3 × 10 6 M ⊙ at the center of Leo I, the most distant dwarf spheroidal galaxy of the Milky Way. This black hole, comparable in mass to the Milky Way’s Sgr A*, places the system >2 orders of magnitude above the standard M • – M ⋆ relation. We investigate the possibility, from a dynamical standpoint, that Leo I’s stellar system was originally much more massive and, thus, closer to the relation. Extreme tidal disruption from one or two close passages within the Milky Way’s virial radius could have removed most of its stellar mass. A simple analytical model suggests that the progenitor of Leo I could have experienced a mass loss in the range 32%–57% from a single pericenter passage, depending on the stellar velocity dispersion estimate. This mass-loss percentage increases to the range 66%–78% if the pericenter occurs at the minimum distance allowed by current orbital reconstructions. Detailed N -body simulations show that the mass loss could reach ∼90% with up to two passages, again with pericenter distances compatible with the minimum value allowed by Gaia data. Despite very significant uncertainties in the properties of Leo I, we reproduce its current position and velocity dispersion, as well as the final stellar mass enclosed in 1 kpc (∼5 × 10 6 M ⊙ ) within a factor <2. The most recent tidal stream is directed along our line of sight toward Leo I, making it difficult to detect. Evidence from this extreme tidal disruption event could be present in current Gaia data in the form of extended tidal streams.
{"title":"Extreme Tidal Stripping May Explain the Overmassive Black Hole in Leo I: A Proof of Concept","authors":"Fabio Pacucci, Yueying Ni, Abraham Loeb","doi":"10.3847/2041-8213/acff5e","DOIUrl":"https://doi.org/10.3847/2041-8213/acff5e","url":null,"abstract":"Abstract A recent study found dynamical evidence of a supermassive black hole of ∼3 × 10 6 M ⊙ at the center of Leo I, the most distant dwarf spheroidal galaxy of the Milky Way. This black hole, comparable in mass to the Milky Way’s Sgr A*, places the system >2 orders of magnitude above the standard M • – M ⋆ relation. We investigate the possibility, from a dynamical standpoint, that Leo I’s stellar system was originally much more massive and, thus, closer to the relation. Extreme tidal disruption from one or two close passages within the Milky Way’s virial radius could have removed most of its stellar mass. A simple analytical model suggests that the progenitor of Leo I could have experienced a mass loss in the range 32%–57% from a single pericenter passage, depending on the stellar velocity dispersion estimate. This mass-loss percentage increases to the range 66%–78% if the pericenter occurs at the minimum distance allowed by current orbital reconstructions. Detailed N -body simulations show that the mass loss could reach ∼90% with up to two passages, again with pericenter distances compatible with the minimum value allowed by Gaia data. Despite very significant uncertainties in the properties of Leo I, we reproduce its current position and velocity dispersion, as well as the final stellar mass enclosed in 1 kpc (∼5 × 10 6 M ⊙ ) within a factor <2. The most recent tidal stream is directed along our line of sight toward Leo I, making it difficult to detect. Evidence from this extreme tidal disruption event could be present in current Gaia data in the form of extended tidal streams.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"131 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135810972","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acff60
V. Vecchiotti, F. L. Villante, G. Pagliaroli
Abstract IceCube collaboration reported the first high-significance observation of the neutrino emission from the Galactic disk. The observed signal can be due to diffuse emission produced by cosmic rays interacting with interstellar gas but can also arise from a population of sources. In this paper, we evaluate both the diffuse and source contribution by taking advantage of gamma-ray observations and/or theoretical considerations. By comparing our expectations with IceCube measurements, we constrain the fraction of Galactic TeV gamma-ray sources (resolved and unresolved) with hadronic nature. In order to be compatible with the IceCube results, this fraction should be small, or the source proton energy cutoff should be well below the cosmic-ray proton knee. In particular, for a cutoff energy equal to 500 TeV, the fraction of hadronic sources should be less than ∼40% corresponding to a cumulative source flux Φ ν ,s ≤ 2.6 × 10 −10 cm −2 s −1 integrated in the 1–100 TeV energy range. This fraction reduces to ∼20% for energy cutoff reaching the cosmic-ray proton knee around 5 PeV.
{"title":"Unveiling the Nature of Galactic TeV Sources with IceCube Results","authors":"V. Vecchiotti, F. L. Villante, G. Pagliaroli","doi":"10.3847/2041-8213/acff60","DOIUrl":"https://doi.org/10.3847/2041-8213/acff60","url":null,"abstract":"Abstract IceCube collaboration reported the first high-significance observation of the neutrino emission from the Galactic disk. The observed signal can be due to diffuse emission produced by cosmic rays interacting with interstellar gas but can also arise from a population of sources. In this paper, we evaluate both the diffuse and source contribution by taking advantage of gamma-ray observations and/or theoretical considerations. By comparing our expectations with IceCube measurements, we constrain the fraction of Galactic TeV gamma-ray sources (resolved and unresolved) with hadronic nature. In order to be compatible with the IceCube results, this fraction should be small, or the source proton energy cutoff should be well below the cosmic-ray proton knee. In particular, for a cutoff energy equal to 500 TeV, the fraction of hadronic sources should be less than ∼40% corresponding to a cumulative source flux Φ ν ,s ≤ 2.6 × 10 −10 cm −2 s −1 integrated in the 1–100 TeV energy range. This fraction reduces to ∼20% for energy cutoff reaching the cosmic-ray proton knee around 5 PeV.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135965107","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acf9a4
K. Azalee Bostroem, Jeniveve Pearson, Manisha Shrestha, David J. Sand, Stefano Valenti, Saurabh W. Jha, Jennifer E. Andrews, Nathan Smith, Giacomo Terreran, Elizabeth Green, Yize 一泽 Dong 董, Michael Lundquist, Joshua Haislip, Emily T. Hoang, Griffin Hosseinzadeh, Daryl Janzen, Jacob E. Jencson, Vladimir Kouprianov, Emmy Paraskeva, Nicolas E. Meza Retamal, Daniel E. Reichart, Iair Arcavi, Alceste Z. Bonanos, Michael W. Coughlin, Ross Dobson, Joseph Farah, Lluís Galbany, Claudia Gutiérrez, Suzanne Hawley, Leslie Hebb, Daichi Hiramatsu, D. Andrew Howell, Takashi Iijima, Ilya Ilyin, Kiran Jhass, Curtis McCully, Sean Moran, Brett M. Morris, Alessandra C. Mura, Tomás E. Müller-Bravo, James Munday, Megan Newsome, Maria Th. Pabst, Paolo Ochner, Estefania Padilla Gonzalez, Andrea Pastorello, Craig Pellegrino, Lara Piscarreta, Aravind P. Ravi, Andrea Reguitti, Laura Salo, József Vinkó, Kellie de Vos, J. C. Wheeler, G. Grant Williams, Samuel Wyatt
Abstract We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. We identify high-ionization emission features, signatures of interaction with material surrounding the progenitor star, that fade over the first 7 days, with rapid evolution between spectra observed within the same night. We compare the emission lines present and their relative strength to those of other supernovae with early interaction, finding a close match to SN 2020pni and SN 2017ahn in the first spectrum and SN 2014G at later epochs. To physically interpret our observations, we compare them to CMFGEN models with confined, dense circumstellar material around a red supergiant (RSG) progenitor from the literature. We find that very few models reproduce the blended N iii ( λλ 4634.0,4640.6)/C iii ( λλ 4647.5,4650.0) emission lines observed in the first few spectra and their rapid disappearance thereafter, making this a unique diagnostic. From the best models, we find a mass-loss rate of 10 −3 –10 −2 M ⊙ yr −1 , which far exceeds the mass-loss rate for any steady wind, especially for an RSG in the initial mass range of the detected progenitor. These mass-loss rates are, however, similar to rates inferred for other supernovae with early circumstellar interaction. Using the phase when the narrow emission features disappear, we calculate an outer dense radius of circumstellar material R CSM,out ≈ 5 × 10 14 cm, and a mean circumstellar material density of ρ = 5.6 × 10 −14 g cm −3 . This is consistent with the lower limit on the outer radius of the circumstellar material we calculate from the peak H α emission flux, R CSM,out ≳ 9 × 10 13 cm.
{"title":"Early Spectroscopy and Dense Circumstellar Medium Interaction in SN 2023ixf","authors":"K. Azalee Bostroem, Jeniveve Pearson, Manisha Shrestha, David J. Sand, Stefano Valenti, Saurabh W. Jha, Jennifer E. Andrews, Nathan Smith, Giacomo Terreran, Elizabeth Green, Yize 一泽 Dong 董, Michael Lundquist, Joshua Haislip, Emily T. Hoang, Griffin Hosseinzadeh, Daryl Janzen, Jacob E. Jencson, Vladimir Kouprianov, Emmy Paraskeva, Nicolas E. Meza Retamal, Daniel E. Reichart, Iair Arcavi, Alceste Z. Bonanos, Michael W. Coughlin, Ross Dobson, Joseph Farah, Lluís Galbany, Claudia Gutiérrez, Suzanne Hawley, Leslie Hebb, Daichi Hiramatsu, D. Andrew Howell, Takashi Iijima, Ilya Ilyin, Kiran Jhass, Curtis McCully, Sean Moran, Brett M. Morris, Alessandra C. Mura, Tomás E. Müller-Bravo, James Munday, Megan Newsome, Maria Th. Pabst, Paolo Ochner, Estefania Padilla Gonzalez, Andrea Pastorello, Craig Pellegrino, Lara Piscarreta, Aravind P. Ravi, Andrea Reguitti, Laura Salo, József Vinkó, Kellie de Vos, J. C. Wheeler, G. Grant Williams, Samuel Wyatt","doi":"10.3847/2041-8213/acf9a4","DOIUrl":"https://doi.org/10.3847/2041-8213/acf9a4","url":null,"abstract":"Abstract We present the optical spectroscopic evolution of SN 2023ixf seen in subnight cadence spectra from 1.18 to 15 days after explosion. We identify high-ionization emission features, signatures of interaction with material surrounding the progenitor star, that fade over the first 7 days, with rapid evolution between spectra observed within the same night. We compare the emission lines present and their relative strength to those of other supernovae with early interaction, finding a close match to SN 2020pni and SN 2017ahn in the first spectrum and SN 2014G at later epochs. To physically interpret our observations, we compare them to CMFGEN models with confined, dense circumstellar material around a red supergiant (RSG) progenitor from the literature. We find that very few models reproduce the blended N iii ( λλ 4634.0,4640.6)/C iii ( λλ 4647.5,4650.0) emission lines observed in the first few spectra and their rapid disappearance thereafter, making this a unique diagnostic. From the best models, we find a mass-loss rate of 10 −3 –10 −2 M ⊙ yr −1 , which far exceeds the mass-loss rate for any steady wind, especially for an RSG in the initial mass range of the detected progenitor. These mass-loss rates are, however, similar to rates inferred for other supernovae with early circumstellar interaction. Using the phase when the narrow emission features disappear, we calculate an outer dense radius of circumstellar material R CSM,out ≈ 5 × 10 14 cm, and a mean circumstellar material density of ρ = 5.6 × 10 −14 g cm −3 . This is consistent with the lower limit on the outer radius of the circumstellar material we calculate from the peak H α emission flux, R CSM,out ≳ 9 × 10 13 cm.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136117522","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acfed1
Duan-Yuan Gao, Yuan-Chuan Zou
Abstract The recent detection of teraelectronvolt (TeV) photons from the record-breaking gamma-ray burst GRB 221009A during its prompt phase poses challenges for constraining its Lorentz factor. We reevaluate the constraints on the jet Lorentz factor considering a two-zone model, wherein the TeV photons originate from the external shock region while the lower-energy MeV photons come from the internal prompt emission region. By properly accounting for the evolution of the MeV photon spectrum and light curve, we calculate the optical depth for TeV photons and derive a minimum Lorentz factor of about 300. It is consistent with the afterglow modeling for the TeV emission.
{"title":"Jet Lorentz Factor Constraint for GRB 221009A Based on the Optical Depth of the TeV Photons","authors":"Duan-Yuan Gao, Yuan-Chuan Zou","doi":"10.3847/2041-8213/acfed1","DOIUrl":"https://doi.org/10.3847/2041-8213/acfed1","url":null,"abstract":"Abstract The recent detection of teraelectronvolt (TeV) photons from the record-breaking gamma-ray burst GRB 221009A during its prompt phase poses challenges for constraining its Lorentz factor. We reevaluate the constraints on the jet Lorentz factor considering a two-zone model, wherein the TeV photons originate from the external shock region while the lower-energy MeV photons come from the internal prompt emission region. By properly accounting for the evolution of the MeV photon spectrum and light curve, we calculate the optical depth for TeV photons and derive a minimum Lorentz factor of about 300. It is consistent with the afterglow modeling for the TeV emission.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"45 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135810444","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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 : 2023-10-01DOI: 10.3847/2041-8213/acf8cb
Wan-Jin Lu, Zhen-Yin Zhao, F. Y. Wang, Z. G. Dai
Abstract Fast radio bursts (FRBs) are energetic millisecond phenomena in the radio band. Polarimetric studies of repeating FRBs indicate that many of these sources occupy extreme and complex magnetoionized environments. Recently, a frequency-dependent depolarization has been discovered in several repeating FRBs. However, the temporal evolution of polarization properties is limited by the burst rate and observational cadence of telescopes. In this Letter, the temporal evolution of depolarization in repeating FRB 20201124A is explored. Using the simultaneous variation of rotation measure and dispersion measure, we also measure the strength of a magnetic field parallel to the line of sight. The strength ranges from a few μ G to 10 3 μ G. In addition, we find that the evolution of depolarization and magnetic field traces the evolution of rotation measure. Our result supports that the variation of depolarization, rotation measure, and the magnetic field are determined by the same complex magnetoionized screen surrounding the FRB source. The derived properties of the screen are consistent with the wind and the decretion disk of a massive star.
{"title":"Temporal Evolution of Depolarization and Magnetic Field of Fast Radio Burst 20201124A","authors":"Wan-Jin Lu, Zhen-Yin Zhao, F. Y. Wang, Z. G. Dai","doi":"10.3847/2041-8213/acf8cb","DOIUrl":"https://doi.org/10.3847/2041-8213/acf8cb","url":null,"abstract":"Abstract Fast radio bursts (FRBs) are energetic millisecond phenomena in the radio band. Polarimetric studies of repeating FRBs indicate that many of these sources occupy extreme and complex magnetoionized environments. Recently, a frequency-dependent depolarization has been discovered in several repeating FRBs. However, the temporal evolution of polarization properties is limited by the burst rate and observational cadence of telescopes. In this Letter, the temporal evolution of depolarization in repeating FRB 20201124A is explored. Using the simultaneous variation of rotation measure and dispersion measure, we also measure the strength of a magnetic field parallel to the line of sight. The strength ranges from a few μ G to 10 3 μ G. In addition, we find that the evolution of depolarization and magnetic field traces the evolution of rotation measure. Our result supports that the variation of depolarization, rotation measure, and the magnetic field are determined by the same complex magnetoionized screen surrounding the FRB source. The derived properties of the screen are consistent with the wind and the decretion disk of a massive star.","PeriodicalId":55567,"journal":{"name":"Astrophysical Journal Letters","volume":"209 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135606675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"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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