Jenni R French, Sarah L Casewell, Rachael C Amaro, Joshua D Lothringer, L C Mayorga, Stuart P Littlefair, Ben W P Lew, Yifan Zhou, Daniel Apai, Mark S Marley, Vivien Parmentier, Xianyu Tan
Due to their short orbital periods and relatively high flux ratios, irradiated brown dwarfs in binaries with white dwarfs offer better opportunities to study irradiated atmospheres than hot Jupiters, which have lower planet-to-star flux ratios. WD1032+011 is an eclipsing, tidally locked white dwarf–brown dwarf binary with a 9950 K white dwarf orbited by a 69.7 MJup brown dwarf in a 0.09 day orbit. We present time-resolved Hubble Space Telescope Wide Field Camera 3 spectrophotometric data of WD1032+011. We isolate the phase-dependent spectra of WD1032+011B, finding a 210 K difference in brightness temperature between the dayside and nightside. The spectral type of the brown dwarf is identified as L1 peculiar, with atmospheric retrievals and comparison to field brown dwarfs showing evidence for a cloud-free atmosphere. The retrieved temperature of the dayside is 1748$^{+66}_{-67}$ K, with a nightside temperature of 1555$^{+76}_{-62}$ K, showing an irradiation-driven temperature contrast coupled with inefficient heat redistribution from the dayside to the nightside. The brown dwarf radius is inflated, likely due to the constant irradiation from the white dwarf, making it the only known inflated brown dwarf in an eclipsing white dwarf–brown dwarf binary.
{"title":"The only inflated brown dwarf in an eclipsing white dwarf–brown dwarf binary: WD1032+011B","authors":"Jenni R French, Sarah L Casewell, Rachael C Amaro, Joshua D Lothringer, L C Mayorga, Stuart P Littlefair, Ben W P Lew, Yifan Zhou, Daniel Apai, Mark S Marley, Vivien Parmentier, Xianyu Tan","doi":"10.1093/mnras/stae2121","DOIUrl":"https://doi.org/10.1093/mnras/stae2121","url":null,"abstract":"Due to their short orbital periods and relatively high flux ratios, irradiated brown dwarfs in binaries with white dwarfs offer better opportunities to study irradiated atmospheres than hot Jupiters, which have lower planet-to-star flux ratios. WD1032+011 is an eclipsing, tidally locked white dwarf–brown dwarf binary with a 9950 K white dwarf orbited by a 69.7 MJup brown dwarf in a 0.09 day orbit. We present time-resolved Hubble Space Telescope Wide Field Camera 3 spectrophotometric data of WD1032+011. We isolate the phase-dependent spectra of WD1032+011B, finding a 210 K difference in brightness temperature between the dayside and nightside. The spectral type of the brown dwarf is identified as L1 peculiar, with atmospheric retrievals and comparison to field brown dwarfs showing evidence for a cloud-free atmosphere. The retrieved temperature of the dayside is 1748$^{+66}_{-67}$ K, with a nightside temperature of 1555$^{+76}_{-62}$ K, showing an irradiation-driven temperature contrast coupled with inefficient heat redistribution from the dayside to the nightside. The brown dwarf radius is inflated, likely due to the constant irradiation from the white dwarf, making it the only known inflated brown dwarf in an eclipsing white dwarf–brown dwarf binary.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"16 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256121","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
We show that Convolution Neural Networks trained to find strong gravitational lens systems are biased towards systems with larger Einstein radii and large concentrated sources. This selection function is key to fully realising the potential of the large samples of strong gravitational lens systems that will be found in upcoming wide-field surveys. In this paper, we use a CNN and three training datasets to quantify the network selection function and its implication for the many scientific applications of strong gravitational lensing. We use CNNs with similar architecture as is commonly found in the literature. The networks preferentially select systems with larger Einstein radii and larger sources with more concentrated source-light distributions. Increasing the detection significance threshold to 12σ from 8σ results in 50percnt of the selected strong lens systems having Einstein radii θE ≥ 1.04 arcsec from θE ≥ 0.879 arcsec, source radii RS ≥ 0.194 arcsec from RS ≥ 0.178 arcsec and source Sérsic indices $n_{mathrm{Sc}}^{mathrm{S}}$ ≥ 2.62 from $n_{mathrm{Sc}}^{mathrm{S}}$ ≥ 2.55. The model trained to find lensed quasars shows a stronger preference for higher lens ellipticities than those trained to find lensed galaxies. The selection function is independent of the slope of the power-law of the mass profiles, hence measurements of this quantity will be unaffected. The lens finder selection function reinforces that of the lensing cross-section, and thus we expect our findings to be a general result for all galaxy-galaxy and galaxy-quasar lens finding neural networks.
{"title":"Selection functions of strong lens finding neural networks","authors":"A Herle, C M O’Riordan, S Vegetti","doi":"10.1093/mnras/stae2106","DOIUrl":"https://doi.org/10.1093/mnras/stae2106","url":null,"abstract":"We show that Convolution Neural Networks trained to find strong gravitational lens systems are biased towards systems with larger Einstein radii and large concentrated sources. This selection function is key to fully realising the potential of the large samples of strong gravitational lens systems that will be found in upcoming wide-field surveys. In this paper, we use a CNN and three training datasets to quantify the network selection function and its implication for the many scientific applications of strong gravitational lensing. We use CNNs with similar architecture as is commonly found in the literature. The networks preferentially select systems with larger Einstein radii and larger sources with more concentrated source-light distributions. Increasing the detection significance threshold to 12σ from 8σ results in 50percnt of the selected strong lens systems having Einstein radii θE ≥ 1.04 arcsec from θE ≥ 0.879 arcsec, source radii RS ≥ 0.194 arcsec from RS ≥ 0.178 arcsec and source Sérsic indices $n_{mathrm{Sc}}^{mathrm{S}}$ ≥ 2.62 from $n_{mathrm{Sc}}^{mathrm{S}}$ ≥ 2.55. The model trained to find lensed quasars shows a stronger preference for higher lens ellipticities than those trained to find lensed galaxies. The selection function is independent of the slope of the power-law of the mass profiles, hence measurements of this quantity will be unaffected. The lens finder selection function reinforces that of the lensing cross-section, and thus we expect our findings to be a general result for all galaxy-galaxy and galaxy-quasar lens finding neural networks.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"17 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256124","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Yashvardhan Tomar, Cuc Dinh, Gongjie Li, Douglas Lin
Rotating super-massive black holes drive Lense-Thirring effects, which induce orbit nodal and eccentricity vector precession in their vicinity. Typically, these relativistic effects are quite small, but for the case of close-in orbits that are additionally perturbed by an outer intermediate mass companion (IMC), we show that the Lense-Thirring effects can lead to markedly different dynamical behaviour. Using REBOUND N-body simulations, we show that resonances occur considering both the Lense-Thirring effect and secular perturbations from the IMC, and it can excite the inclination of the orbits, an order of magnitude higher than that achieved solely due to secular three-body effects. We also examine the sensitivity of the inclination growth on the profile of the IMC and find that the excitation is highest for a companion to SMBH mass ratio of 1:1000 and for companions that orbit the SMBH on closer-in orbits. In addition, we investigate how varying the spin direction of the SMBH affects the inclination of the orbits. We find no excitation in the eccentricity of the orbits since the resonance is on the nodal angle, and the fast precession suppresses Kozai cycles. Finally, we note how the Lense-Thirring effect reduces the stability of the three-body system, enhancing the scattering rate between the test particles and the IMC, and thus making disruption events more likely in the system.
{"title":"Influence of the lense-thirring effect on stellar orbits around a spinning supermassive black hole","authors":"Yashvardhan Tomar, Cuc Dinh, Gongjie Li, Douglas Lin","doi":"10.1093/mnras/stae2123","DOIUrl":"https://doi.org/10.1093/mnras/stae2123","url":null,"abstract":"Rotating super-massive black holes drive Lense-Thirring effects, which induce orbit nodal and eccentricity vector precession in their vicinity. Typically, these relativistic effects are quite small, but for the case of close-in orbits that are additionally perturbed by an outer intermediate mass companion (IMC), we show that the Lense-Thirring effects can lead to markedly different dynamical behaviour. Using REBOUND N-body simulations, we show that resonances occur considering both the Lense-Thirring effect and secular perturbations from the IMC, and it can excite the inclination of the orbits, an order of magnitude higher than that achieved solely due to secular three-body effects. We also examine the sensitivity of the inclination growth on the profile of the IMC and find that the excitation is highest for a companion to SMBH mass ratio of 1:1000 and for companions that orbit the SMBH on closer-in orbits. In addition, we investigate how varying the spin direction of the SMBH affects the inclination of the orbits. We find no excitation in the eccentricity of the orbits since the resonance is on the nodal angle, and the fast precession suppresses Kozai cycles. Finally, we note how the Lense-Thirring effect reduces the stability of the three-body system, enhancing the scattering rate between the test particles and the IMC, and thus making disruption events more likely in the system.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"12 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
A B Drake, D J B Smith, M J Hardcastle, P N Best, R Kondapally, M I Arnaudova, S Das, S Shenoy, K J Duncan, H J A Röttgering, C Tasse
We present an analysis of 152,355 radio sources identified in the second data release of the LOFAR Two Metre Sky Survey (LoTSS-DR2) with Sloan Digital Sky Survey (SDSS) spectroscopic redshifts in the range 0.00 < z < 0.57. Using Monte Carlo simulations we determine the reliability of each source exhibiting an excess in radio luminosity relative to that predicted from their Hα emission, and, for a subset of 124,023 sources we combine this measurement with a full BPT analysis. Using these two independent diagnostics we determine the reliability of each source hosting a supermassive black hole of high or low Eddington-scaled accretion rate, and combine the measurements to determine the reliability of sources belonging to each of four physical classes of objects: star forming galaxies (SFGs), radio-quiet active galactic nuclei (RQAGN), and high- or low-excitation radio galaxies (HERGs or emission-line LERGs). The result is a catalogue which enables user-defined samples of radio sources with a reliability threshold suited to their science goal e.g. prioritising purity or completeness. Here we select high-confidence samples of radio sources (>90% reliability) to report: 38,588 radio-excess AGN in the LoTSS DR2 sample (362 HERGs, and 12,648 emission-line LERGs), together with 38,729 SFGs, and 18,726 RQAGN. We validate these results through comparison to literature using independent emission-line measurements, and to widely-adopted WISE photometric selection techniques. While our use of SDSS spectroscopy limits our current analysis to ∼4 percent of the LoTSS-DR2 catalogue, our method is directly applicable to data from the forthcoming WEAVE-LOFAR survey which will obtain over a million spectra of 144 MHz selected sources.
{"title":"The LOFAR two metre sky survey data release 2: probabilistic spectral source classifications and faint radio source demographics","authors":"A B Drake, D J B Smith, M J Hardcastle, P N Best, R Kondapally, M I Arnaudova, S Das, S Shenoy, K J Duncan, H J A Röttgering, C Tasse","doi":"10.1093/mnras/stae2117","DOIUrl":"https://doi.org/10.1093/mnras/stae2117","url":null,"abstract":"We present an analysis of 152,355 radio sources identified in the second data release of the LOFAR Two Metre Sky Survey (LoTSS-DR2) with Sloan Digital Sky Survey (SDSS) spectroscopic redshifts in the range 0.00 &lt; z &lt; 0.57. Using Monte Carlo simulations we determine the reliability of each source exhibiting an excess in radio luminosity relative to that predicted from their Hα emission, and, for a subset of 124,023 sources we combine this measurement with a full BPT analysis. Using these two independent diagnostics we determine the reliability of each source hosting a supermassive black hole of high or low Eddington-scaled accretion rate, and combine the measurements to determine the reliability of sources belonging to each of four physical classes of objects: star forming galaxies (SFGs), radio-quiet active galactic nuclei (RQAGN), and high- or low-excitation radio galaxies (HERGs or emission-line LERGs). The result is a catalogue which enables user-defined samples of radio sources with a reliability threshold suited to their science goal e.g. prioritising purity or completeness. Here we select high-confidence samples of radio sources (&gt;90% reliability) to report: 38,588 radio-excess AGN in the LoTSS DR2 sample (362 HERGs, and 12,648 emission-line LERGs), together with 38,729 SFGs, and 18,726 RQAGN. We validate these results through comparison to literature using independent emission-line measurements, and to widely-adopted WISE photometric selection techniques. While our use of SDSS spectroscopy limits our current analysis to ∼4 percent of the LoTSS-DR2 catalogue, our method is directly applicable to data from the forthcoming WEAVE-LOFAR survey which will obtain over a million spectra of 144 MHz selected sources.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"54 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256120","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Boyuan Liu, Tilman Hartwig, Nina S Sartorio, Irina Dvorkin, Guglielmo Costa, Filippo Santoliquido, Anastasia Fialkov, Ralf S Klessen, Volker Bromm
The gravitational wave (GW) signal from binary black hole (BBH) mergers is a promising probe of Population III (Pop III) stars. To fully unleash the power of the GW probe, one important step is to understand the relative importance and features of different BBH evolution channels. We model two channels, isolated binary stellar evolution (IBSE) and nuclear star cluster-dynamical hardening (NSC-DH), in one theoretical framework based on the semi-analytical code a-sloth, under various assumptions on Pop III initial mass function (IMF), initial binary statistics and high-z nuclear star clusters (NSCs). The NSC-DH channel contributes $sim 8-95{{%}}$ of Pop III BBH mergers across cosmic history, with higher contributions achieved by initially wider binary stars, more top-heavy IMFs, and more abundant high-z NSCs. The dimensionless stochastic GW background (SGWB) produced by Pop III BBH mergers has peak values $Omega ^{rm peak}_{rm GW}sim 10^{-11}-8times 10^{-11}$ around observer-frame frequencies $nu sim 10-100 rm Hz$. The Pop III contribution can be a non-negligible ($sim 2-32{{%}}$) component in the total SGWB at $nu lesssim 10 rm Hz$. The estimated detection rates of Pop III BBH mergers by the Einstein Telescope are $sim 6-230 rm yr^{-1}$ and $sim 30-1230 rm yr^{-1}$ for the NSC-DH and IBSE channels, respectively. Pop III BBH mergers in NSCs are more massive than those from IBSE, so they dominate the Pop III SGWB below 20 Hz in most cases. Besides, the detection rate of Pop III BBH mergers involving at least one intermediate-mass BH above $100 rm M_odot$ by the Einstein Telescope is $sim 0.5-200 rm yr^{-1}$ in NSCs but remains below $0.1 rm yr^{-1}$ for IBSE.
来自双黑洞（BBH）合并的引力波（GW）信号是种群III（Pop III）恒星的一个很有前途的探测器。要充分发挥引力波探测器的威力，重要的一步是了解不同BBH演化通道的相对重要性和特征。我们基于半分析代码 a-sloth，在 Pop III 初始质量函数（IMF）、初始双星统计和高兹核星团（NSCs）的各种假设下，在一个理论框架中模拟了两种演化途径：孤立双星演化（IBSE）和核星团-动力硬化（NSC-DH）。在整个宇宙历史中，NSC-DH通道对Pop III BBH合并的贡献为8-95{{/{%}}$，初始双星更宽、IMF更顶重以及高兹核星团更丰富的情况下，NSC-DH通道的贡献会更高。波普III BBH合并产生的无量纲随机全球变暖背景（SGWB）在观测者帧频率$nu sim 10-100rm Hz$附近具有峰值。在观察者帧频率为10-100 rm Hz$时，波普III的贡献可能是总SGWB中不可忽略的（$sim 2-32{{/%}}$）组成部分。爱因斯坦望远镜对波普III BBH并合的探测率估计分别是：NSC-DH和IBSE通道分别为$sim 6-230rm yr^{-1}$和$sim 30-1230rm yr^{-1}$。NSC 中的 Pop III BBH 合并比来自 IBSE 的合并质量更大，因此在大多数情况下，它们在 20 Hz 以下的 Pop III SGWB 中占主导地位。此外，爱因斯坦望远镜对Pop III BBH合并的探测率在NSCs中是$sim 0.5-200rm yr^{-1}$，而在IBSE中则低于$0.1rm yr^{-1}$。
{"title":"Gravitational waves from mergers of Population III binary black holes: roles played by two evolution channels","authors":"Boyuan Liu, Tilman Hartwig, Nina S Sartorio, Irina Dvorkin, Guglielmo Costa, Filippo Santoliquido, Anastasia Fialkov, Ralf S Klessen, Volker Bromm","doi":"10.1093/mnras/stae2120","DOIUrl":"https://doi.org/10.1093/mnras/stae2120","url":null,"abstract":"The gravitational wave (GW) signal from binary black hole (BBH) mergers is a promising probe of Population III (Pop III) stars. To fully unleash the power of the GW probe, one important step is to understand the relative importance and features of different BBH evolution channels. We model two channels, isolated binary stellar evolution (IBSE) and nuclear star cluster-dynamical hardening (NSC-DH), in one theoretical framework based on the semi-analytical code a-sloth, under various assumptions on Pop III initial mass function (IMF), initial binary statistics and high-z nuclear star clusters (NSCs). The NSC-DH channel contributes $sim 8-95{{%}}$ of Pop III BBH mergers across cosmic history, with higher contributions achieved by initially wider binary stars, more top-heavy IMFs, and more abundant high-z NSCs. The dimensionless stochastic GW background (SGWB) produced by Pop III BBH mergers has peak values $Omega ^{rm peak}_{rm GW}sim 10^{-11}-8times 10^{-11}$ around observer-frame frequencies $nu sim 10-100 rm Hz$. The Pop III contribution can be a non-negligible ($sim 2-32{{%}}$) component in the total SGWB at $nu lesssim 10 rm Hz$. The estimated detection rates of Pop III BBH mergers by the Einstein Telescope are $sim 6-230 rm yr^{-1}$ and $sim 30-1230 rm yr^{-1}$ for the NSC-DH and IBSE channels, respectively. Pop III BBH mergers in NSCs are more massive than those from IBSE, so they dominate the Pop III SGWB below 20 Hz in most cases. Besides, the detection rate of Pop III BBH mergers involving at least one intermediate-mass BH above $100 rm M_odot$ by the Einstein Telescope is $sim 0.5-200 rm yr^{-1}$ in NSCs but remains below $0.1 rm yr^{-1}$ for IBSE.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"54 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256123","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Searches for primordial non-Gaussianity in cosmological perturbations are a key means of revealing novel primordial physics. However, robustly extracting signatures of primordial non-Gaussianity from non-linear scales of the late-time Universe is an open problem. In this paper, we apply k-Nearest Neighbor cumulative distribution functions, kNN-CDFs, to the quijote-png simulations to explore the sensitivity of kNN-CDFs to primordial non-Gaussianity. An interesting result is that for halo samples with Mh < 1014 M⊙ h−1, the kNN-CDFs respond to equilateral PNG in a manner distinct from the other parameters. This persists in the galaxy catalogs in redshift space and can be differentiated from the impact of galaxy modelling, at least within the halo occupation distribution (HOD) framework considered here. kNN-CDFs are related to counts-in-cells and, through mapping a subset of the kNN-CDF measurements into the count-in-cells picture, we show that our results can be modeled analytically. A caveat of the analysis is that we only consider the HOD framework, including assembly bias. It will be interesting to validate these results with other techniques for modeling the galaxy–halo connection, e.g. (hybrid) effective field theory or semi-analytical methods.
{"title":"Small-scale signatures of primordial non-Gaussianity in k-Nearest neighbour cumulative distribution functions","authors":"William R Coulton, Tom Abel, Arka Banerjee","doi":"10.1093/mnras/stae2108","DOIUrl":"https://doi.org/10.1093/mnras/stae2108","url":null,"abstract":"Searches for primordial non-Gaussianity in cosmological perturbations are a key means of revealing novel primordial physics. However, robustly extracting signatures of primordial non-Gaussianity from non-linear scales of the late-time Universe is an open problem. In this paper, we apply k-Nearest Neighbor cumulative distribution functions, kNN-CDFs, to the quijote-png simulations to explore the sensitivity of kNN-CDFs to primordial non-Gaussianity. An interesting result is that for halo samples with Mh &lt; 1014 M⊙ h−1, the kNN-CDFs respond to equilateral PNG in a manner distinct from the other parameters. This persists in the galaxy catalogs in redshift space and can be differentiated from the impact of galaxy modelling, at least within the halo occupation distribution (HOD) framework considered here. kNN-CDFs are related to counts-in-cells and, through mapping a subset of the kNN-CDF measurements into the count-in-cells picture, we show that our results can be modeled analytically. A caveat of the analysis is that we only consider the HOD framework, including assembly bias. It will be interesting to validate these results with other techniques for modeling the galaxy–halo connection, e.g. (hybrid) effective field theory or semi-analytical methods.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"24 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256126","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Martin A Bourne, Davide Fiacconi, Debora Sijacki, Joanna M Piotrowska, Sophie Koudmani
Parsec-scale separation supermassive black hole binaries in the centre of gas-rich galaxy merger remnants could be surrounded by massive circumbinary discs (CBDs). Black hole mass and spin evolution during the gas-rich binary inspiral are crucial in determining the direction and power of relativistic jets that radio observations with LOFAR and SKAO will probe, and for predicting gravitational wave (GW) emission that IPTA and LISA will measure. We present 3D hydrodynamic simulations capturing gas-rich, self-gravitating CBDs around a 2 × 106 M⊙ supermassive black hole binary, that probe different mass ratios, eccentricities and inclinations. We employ a sub-grid Shakura-Sunyaev accretion disc to self-consistently model black hole mass and spin evolution together with super-Lagrangian refinement techniques to resolve gas flows, streams and mini-discs within the cavity, which play a fundamental role in torquing and feeding the binary. We find that higher mass ratio and eccentric binaries result in larger cavities, while retrograde binaries result in smaller cavities. All of the simulated binaries are expected to shrink with net gravitational torques being negative. Unlike previous simulations, we do not find preferential accretion onto the secondary black hole. This implies smaller chirp masses at coalescence and hence a weaker GW background. Critically this means that spin-alignment is faster than the binary inspiral timescale even for low mass ratios. When considering initially misaligned systems, the orientation of the mini-discs around each black hole can vary significantly. We discuss the implications of this behaviour for black hole spin alignment and highlight the need for broader parameter space studies of misaligned systems to understand the impact on black hole recoil velocities.
{"title":"Dynamics and spin alignment in massive, gravito-turbulent circumbinary discs around supermassive black hole binaries","authors":"Martin A Bourne, Davide Fiacconi, Debora Sijacki, Joanna M Piotrowska, Sophie Koudmani","doi":"10.1093/mnras/stae2143","DOIUrl":"https://doi.org/10.1093/mnras/stae2143","url":null,"abstract":"Parsec-scale separation supermassive black hole binaries in the centre of gas-rich galaxy merger remnants could be surrounded by massive circumbinary discs (CBDs). Black hole mass and spin evolution during the gas-rich binary inspiral are crucial in determining the direction and power of relativistic jets that radio observations with LOFAR and SKAO will probe, and for predicting gravitational wave (GW) emission that IPTA and LISA will measure. We present 3D hydrodynamic simulations capturing gas-rich, self-gravitating CBDs around a 2 × 106 M⊙ supermassive black hole binary, that probe different mass ratios, eccentricities and inclinations. We employ a sub-grid Shakura-Sunyaev accretion disc to self-consistently model black hole mass and spin evolution together with super-Lagrangian refinement techniques to resolve gas flows, streams and mini-discs within the cavity, which play a fundamental role in torquing and feeding the binary. We find that higher mass ratio and eccentric binaries result in larger cavities, while retrograde binaries result in smaller cavities. All of the simulated binaries are expected to shrink with net gravitational torques being negative. Unlike previous simulations, we do not find preferential accretion onto the secondary black hole. This implies smaller chirp masses at coalescence and hence a weaker GW background. Critically this means that spin-alignment is faster than the binary inspiral timescale even for low mass ratios. When considering initially misaligned systems, the orientation of the mini-discs around each black hole can vary significantly. We discuss the implications of this behaviour for black hole spin alignment and highlight the need for broader parameter space studies of misaligned systems to understand the impact on black hole recoil velocities.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"208 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142269291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Exploiting the Persistent Homology technique and its complementary representations, we examine the footprint of summed neutrino mass (Mν) in the various density fields simulated by the publicly available Quijote suite. The evolution of topological features by utilizing the super-level filtration on three-dimensional density fields at zero redshift, reveals a remarkable benchmark for constraining the cosmological parameters, particularly Mν and σ8. The abundance of independent closed surfaces (voids) compared to the connected components (clusters) and independent loops (filaments), is more sensitive to the presence of Mν for R = 5 Mpc h−1 irrespective of whether using the total matter density field (m) or CDM+baryons field (cb). Reducing the degeneracy between Mν and σ8 is achieved via Persistent Homology for the m field but not for the cb field. The uncertainty of Mν at 1σ confidenc interval from the joint analysis of Persistent Homology vectorization for the m and cb fields smoothed by R = 5 Mpc h−1 at z = 0 reaches 0.0152 eV and 0.1242 eV, respectively. Noticing the use of the 3-dimensional underlying density field at z = 0, the mentioned uncertainties can be treated as the theoretical lower limits.
{"title":"Imprint of massive neutrinos on Persistent Homology of large-scale structure","authors":"M H Jalali Kanafi, S Ansarifard, S M S Movahed","doi":"10.1093/mnras/stae2044","DOIUrl":"https://doi.org/10.1093/mnras/stae2044","url":null,"abstract":"Exploiting the Persistent Homology technique and its complementary representations, we examine the footprint of summed neutrino mass (Mν) in the various density fields simulated by the publicly available Quijote suite. The evolution of topological features by utilizing the super-level filtration on three-dimensional density fields at zero redshift, reveals a remarkable benchmark for constraining the cosmological parameters, particularly Mν and σ8. The abundance of independent closed surfaces (voids) compared to the connected components (clusters) and independent loops (filaments), is more sensitive to the presence of Mν for R = 5 Mpc h−1 irrespective of whether using the total matter density field (m) or CDM+baryons field (cb). Reducing the degeneracy between Mν and σ8 is achieved via Persistent Homology for the m field but not for the cb field. The uncertainty of Mν at 1σ confidenc interval from the joint analysis of Persistent Homology vectorization for the m and cb fields smoothed by R = 5 Mpc h−1 at z = 0 reaches 0.0152 eV and 0.1242 eV, respectively. Noticing the use of the 3-dimensional underlying density field at z = 0, the mentioned uncertainties can be treated as the theoretical lower limits.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"31 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256160","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
The overall objective of this study is to investigate claims found in the literature that fossil groups, characterized by a large magnitude gap between their two brightest galaxies, are darker, i.e. exhibit higher mass-to-light ratios (M/L), compared to regular groups. Specifically, we aim to measure the mass of these systems using the weak gravitational lensing technique. To achieve this, we obtained deep images of four fossil systems with the CFHT telescope in the r and g bands. Through a careful process of weak gravitational shear measurement, including corrections for the point spread function (PSF) and contamination from group and foreground galaxies, we fit NFW models and obtained mass measurements as a result. Similarly, we quantified the light distribution produced by these groups, taking into account relevant data gaps in the images due to the presence of bright stars, as well as contamination from foreground and background galaxies. We obtained masses and M/L ratios that are consistent with previous results where mass was estimated from galaxy dynamics. Indeed, the four fossil systems studied here exhibit high M/L ratios compared to the general population of systems. Drawing more generalizable conclusions from a sample of only four systems is challenging. However, the procedure outlined in this study can be applied to large image surveys, allowing for a revisiting of this question with significantly reduced statistical uncertainties. This will enable a more homogeneous comparison between fossil groups and clusters and the overall population.
这项研究的总体目标是调查文献中的说法，即化石星系群的两个最亮星系之间存在很大的等级差，与普通星系群相比，化石星系群更暗，即表现出更高的质量光比（M/L）。具体来说，我们的目标是利用弱引力透镜技术测量这些星系的质量。为此，我们利用 CFHT 望远镜的 r 波段和 g 波段获得了四个化石系统的深度图像。通过细致的弱引力剪切测量过程，包括对点扩散函数（PSF）以及群星系和前景星系污染的校正，我们拟合了 NFW 模型，并由此获得了质量测量值。同样，我们对这些星系群产生的光分布进行了量化，同时考虑到了图像中由于亮星的存在而造成的相关数据缺口，以及前景和背景星系的污染。我们得到的质量和M/L比与之前通过星系动力学估算质量的结果一致。事实上，与一般系统相比，这里研究的四个化石系统表现出很高的M/L比。从仅有的四个系统样本中得出更具普遍性的结论是很有挑战性的。不过，本研究中概述的程序可以应用于大型图像巡天，从而在大大降低统计不确定性的情况下重新审视这一问题。这将使化石群和星团与总体之间的比较更加一致。
{"title":"Fossil Groups analysis using weak gravitational lensing","authors":"M Castejon, E S Cypriano, A Z Vitorelli","doi":"10.1093/mnras/stae2078","DOIUrl":"https://doi.org/10.1093/mnras/stae2078","url":null,"abstract":"The overall objective of this study is to investigate claims found in the literature that fossil groups, characterized by a large magnitude gap between their two brightest galaxies, are darker, i.e. exhibit higher mass-to-light ratios (M/L), compared to regular groups. Specifically, we aim to measure the mass of these systems using the weak gravitational lensing technique. To achieve this, we obtained deep images of four fossil systems with the CFHT telescope in the r and g bands. Through a careful process of weak gravitational shear measurement, including corrections for the point spread function (PSF) and contamination from group and foreground galaxies, we fit NFW models and obtained mass measurements as a result. Similarly, we quantified the light distribution produced by these groups, taking into account relevant data gaps in the images due to the presence of bright stars, as well as contamination from foreground and background galaxies. We obtained masses and M/L ratios that are consistent with previous results where mass was estimated from galaxy dynamics. Indeed, the four fossil systems studied here exhibit high M/L ratios compared to the general population of systems. Drawing more generalizable conclusions from a sample of only four systems is challenging. However, the procedure outlined in this study can be applied to large image surveys, allowing for a revisiting of this question with significantly reduced statistical uncertainties. This will enable a more homogeneous comparison between fossil groups and clusters and the overall population.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"1 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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}
Mahasweta Bhattacharya, Aditya S Mondal, Mayukh Pahari, Biplab Raychaudhuri, Rohit Ghosh, Gulab C Dewangan
The accreting millisecond X-ray pulsar IGR J17498-2921 went into X-ray outburst on April 13-15, 2023, for the first time since its discovery on August 11, 2011. Here, we report on the first follow-up NuSTAR observation of the source, performed on April 23, 2023, around ten days after the peak of the outburst. The NuSTAR spectrum of the persistent emission (3 − 60 keV band) is well described by an absorbed blackbody with a temperature of kTbb = 1.61 ± 0.04 keV, most likely arising from the NS surface and a Comptonization component with power-law index Γ = 1.79 ± 0.02, arising from a hot corona at kTe = 16 ± 2 keV. The X-ray spectrum of the source shows robust reflection features which have not been observed before. We use a couple of self-consistent reflection models, relxill and relxillCp, to fit the reflection features. We find an upper limit to the inner disc radius of 6 RISCO and 9 RISCO from relxill and relxillCp model, respectively. The inclination of the system is estimated to be ≃ 40○ from both reflection models. Assuming magnetic truncation of the accretion disc, the upper limit of magnetic field strength at the pole of the NS is found to be B ≲ 1.8 × 108 G. Furthermore, the NuSTAR observation revealed two type I X-ray bursts and the burst spectroscopy confirms the thermonuclear nature of the burst. The blackbody temperature reaches nearly 2.2 keV at the peak of the burst.
{"title":"Relativistic X-ray reflection from the accreting millisecond X-ray pulsar IGR J17498-2921","authors":"Mahasweta Bhattacharya, Aditya S Mondal, Mayukh Pahari, Biplab Raychaudhuri, Rohit Ghosh, Gulab C Dewangan","doi":"10.1093/mnras/stae2135","DOIUrl":"https://doi.org/10.1093/mnras/stae2135","url":null,"abstract":"The accreting millisecond X-ray pulsar IGR J17498-2921 went into X-ray outburst on April 13-15, 2023, for the first time since its discovery on August 11, 2011. Here, we report on the first follow-up NuSTAR observation of the source, performed on April 23, 2023, around ten days after the peak of the outburst. The NuSTAR spectrum of the persistent emission (3 − 60 keV band) is well described by an absorbed blackbody with a temperature of kTbb = 1.61 ± 0.04 keV, most likely arising from the NS surface and a Comptonization component with power-law index Γ = 1.79 ± 0.02, arising from a hot corona at kTe = 16 ± 2 keV. The X-ray spectrum of the source shows robust reflection features which have not been observed before. We use a couple of self-consistent reflection models, relxill and relxillCp, to fit the reflection features. We find an upper limit to the inner disc radius of 6 RISCO and 9 RISCO from relxill and relxillCp model, respectively. The inclination of the system is estimated to be ≃ 40○ from both reflection models. Assuming magnetic truncation of the accretion disc, the upper limit of magnetic field strength at the pole of the NS is found to be B ≲ 1.8 × 108 G. Furthermore, the NuSTAR observation revealed two type I X-ray bursts and the burst spectroscopy confirms the thermonuclear nature of the burst. The blackbody temperature reaches nearly 2.2 keV at the peak of the burst.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"16 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142256161","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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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