Rebecca G. Martin, Stephen Lepp, Bing Zhang, C. J. Nixon, Anna C. Childs
With hydrodynamical simulations we examine the evolution of a highly misaligned circumbinary disc around a black hole binary including the effects of general relativity. We show that a disc mass of just a few percent of the binary mass can significantly increase the binary eccentricity through von-Zeipel–Kozai–Lidov (ZKL) like oscillations provided that the disc lifetime is longer than the ZKL oscillation timescale. The disc begins as a relatively narrow ring of material far from the binary and spreads radially. When the binary becomes highly eccentric, disc breaking forms an inner disc ring that quickly aligns to polar. The polar ring drives fast retrograde apsidal precession of the binary that weakens the ZKL effect. This allows the binary eccentricity to remain at a high level and may significantly shorten the black hole merger time. The mechanism requires the initial disc inclination relative to the binary to be closer to retrograde than to prograde.
{"title":"Mergers of black hole binaries driven by misaligned circumbinary discs","authors":"Rebecca G. Martin, Stephen Lepp, Bing Zhang, C. J. Nixon, Anna C. Childs","doi":"10.1093/mnrasl/slad174","DOIUrl":"https://doi.org/10.1093/mnrasl/slad174","url":null,"abstract":"With hydrodynamical simulations we examine the evolution of a highly misaligned circumbinary disc around a black hole binary including the effects of general relativity. We show that a disc mass of just a few percent of the binary mass can significantly increase the binary eccentricity through von-Zeipel–Kozai–Lidov (ZKL) like oscillations provided that the disc lifetime is longer than the ZKL oscillation timescale. The disc begins as a relatively narrow ring of material far from the binary and spreads radially. When the binary becomes highly eccentric, disc breaking forms an inner disc ring that quickly aligns to polar. The polar ring drives fast retrograde apsidal precession of the binary that weakens the ZKL effect. This allows the binary eccentricity to remain at a high level and may significantly shorten the black hole merger time. The mechanism requires the initial disc inclination relative to the binary to be closer to retrograde than to prograde.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"56 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139266612","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}
Abstract Spectroscopic analysis of Lyα damping wings of bright sources at z > 6 is a promising way to measure the reionization history of the universe. However, the theoretical interpretation of the damping wings is challenging due to the inhomogeneous nature of the reionization process and the proximity effect of bright sources. In this Letter, we analyze the damping wings arising from the neutral patches in the radiative transfer cosmological simulation suite Cosmic Reionization on Computers (CROC). We find that the damping wing profile remains a tight function of volume-weighted neutral fraction <xHI > v, especially when <xHI > v > 0.5, despite the patchy nature of reionization and the proximity effect. This small scatter indicates that with a well-measured damping wing profile, we could constrain the volume-weighted neutral fraction as precise as Δ < xHI > v ≲ 0.1 in the first half of reionization. Due to resonant Lyα absorption from the residual neutral hydrogen inside the ionized bubble, it may be challenging to find the starting point of the damping wing for faint sources like normal galaxies or gamma-ray bursts. However, for bright sources like quasars, it is hopeful to measure the entire damping wing and use them to measure the neutral fraction accurately.
{"title":"The Characteristic Shape of Damping Wings During Reionization","authors":"Huanqing Chen","doi":"10.1093/mnrasl/slad171","DOIUrl":"https://doi.org/10.1093/mnrasl/slad171","url":null,"abstract":"Abstract Spectroscopic analysis of Lyα damping wings of bright sources at z &gt; 6 is a promising way to measure the reionization history of the universe. However, the theoretical interpretation of the damping wings is challenging due to the inhomogeneous nature of the reionization process and the proximity effect of bright sources. In this Letter, we analyze the damping wings arising from the neutral patches in the radiative transfer cosmological simulation suite Cosmic Reionization on Computers (CROC). We find that the damping wing profile remains a tight function of volume-weighted neutral fraction &lt;xHI &gt; v, especially when &lt;xHI &gt; v &gt; 0.5, despite the patchy nature of reionization and the proximity effect. This small scatter indicates that with a well-measured damping wing profile, we could constrain the volume-weighted neutral fraction as precise as Δ &lt; xHI &gt; v ≲ 0.1 in the first half of reionization. Due to resonant Lyα absorption from the residual neutral hydrogen inside the ionized bubble, it may be challenging to find the starting point of the damping wing for faint sources like normal galaxies or gamma-ray bursts. However, for bright sources like quasars, it is hopeful to measure the entire damping wing and use them to measure the neutral fraction accurately.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"134993284","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}
Solar flares – the most prominent manifestation of solar activity – typically manifest themselves as a single or a set of luminous arcs (magnetic flux tubes) rooted in regions of opposite polarity in the photosphere. However, a careful analysis of archival data from the Hinode satellite reveals occasional surprising cases of flaring arcs whose footpoints belong to regions of the same polarity or to areas without any appreciable magnetic field. Despite the counterintuitive nature of this phenomenon, it can be reasonably interpreted in the framework of the so-called ‘topological model’ of magnetic reconnection, whereby a magnetic null point is formed owing to a specific superposition of influences from remote sources rather than by local current systems. As a result, the energy release propagates along the separator of a flipping two-dome structure rather than along a fixed magnetic field line. Therefore, the luminous arc no longer needs to be associated immediately with the magnetic sources. Here, we report observational cases of the above-mentioned type and provide a theoretical model and numerical simulations.
{"title":"Unipolar solar flares as a manifestation of ‘topological’ magnetic reconnection","authors":"Y. Dumin, B. Somov","doi":"10.1093/mnrasl/slad162","DOIUrl":"https://doi.org/10.1093/mnrasl/slad162","url":null,"abstract":"Solar flares – the most prominent manifestation of solar activity – typically manifest themselves as a single or a set of luminous arcs (magnetic flux tubes) rooted in regions of opposite polarity in the photosphere. However, a careful analysis of archival data from the Hinode satellite reveals occasional surprising cases of flaring arcs whose footpoints belong to regions of the same polarity or to areas without any appreciable magnetic field. Despite the counterintuitive nature of this phenomenon, it can be reasonably interpreted in the framework of the so-called ‘topological model’ of magnetic reconnection, whereby a magnetic null point is formed owing to a specific superposition of influences from remote sources rather than by local current systems. As a result, the energy release propagates along the separator of a flipping two-dome structure rather than along a fixed magnetic field line. Therefore, the luminous arc no longer needs to be associated immediately with the magnetic sources. Here, we report observational cases of the above-mentioned type and provide a theoretical model and numerical simulations.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"14 4","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139278250","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}
Superorbital periods that are observed in the brightness of Be/X-ray binaries may be driven by a misaligned and precessing Be star disc. We examine how the precessing disc model explains the superorbital variation of (i) the magnitude of the observed X-ray outbursts and (ii) the observed colour. With hydrodynamical simulations we show that the magnitude of the average accretion rate on to the neutron star, and therefore the X-ray outbursts, can vary by over an order of magnitude over the superorbital period for Be star spin-orbit misalignments ≳ 70○ as a result of weak tidal truncation. Most Be/X-ray binaries are redder at optical maximum when the disc is viewed closest to face-on since the disc adds a large red component to the emission. However, A0538-66 is redder at optical minimum. This opposite behaviour requires an edge-on disc at optical minimum and a radially narrow disc such that it does not add a large red signature when viewed face-on. For A0538-66, the misalignment of the disc to the binary orbit must be about 70 − 80○ and the inclination of the binary orbit to the line of sight must be similarly high, although restricted to <75○ by the absence of X-ray eclipses.
在Be/X射线双星亮度中观测到的超轨道周期可能是由错位和前冲的Be星盘驱动的。我们研究了前冲圆盘模型如何解释（i）观测到的 X 射线爆发的幅度和（ii）观测到的颜色的超轨道变化。通过流体力学模拟，我们发现由于弱潮汐截断作用，Be 星自旋轨道错位 ≳ 70○ 时，中子星上的平均吸积率大小以及 X 射线爆发的大小在超轨道周期内会有超过一个数量级的变化。大多数Be/X射线双星在光学最大值时的颜色都比较红，这是因为圆盘为发射增加了大量的红色成分。然而，A0538-66在光学最小值时更红。这种相反的表现要求圆盘在光学最小值时边缘朝上，并且圆盘径向较窄，这样在正面观看时就不会增加大量的红色信号。对于 A0538-66，圆盘与双星轨道的偏差必须在 70 - 80 ○左右，双星轨道与视线的倾角也必须同样大，不过由于没有 X 射线日食，倾角被限制在小于 75 ○。
{"title":"Disc precession in Be/X-ray binaries drives superorbital variations of outbursts and colour","authors":"R. Martin, P. Charles","doi":"10.1093/mnrasl/slad170","DOIUrl":"https://doi.org/10.1093/mnrasl/slad170","url":null,"abstract":"Superorbital periods that are observed in the brightness of Be/X-ray binaries may be driven by a misaligned and precessing Be star disc. We examine how the precessing disc model explains the superorbital variation of (i) the magnitude of the observed X-ray outbursts and (ii) the observed colour. With hydrodynamical simulations we show that the magnitude of the average accretion rate on to the neutron star, and therefore the X-ray outbursts, can vary by over an order of magnitude over the superorbital period for Be star spin-orbit misalignments ≳ 70○ as a result of weak tidal truncation. Most Be/X-ray binaries are redder at optical maximum when the disc is viewed closest to face-on since the disc adds a large red component to the emission. However, A0538-66 is redder at optical minimum. This opposite behaviour requires an edge-on disc at optical minimum and a radially narrow disc such that it does not add a large red signature when viewed face-on. For A0538-66, the misalignment of the disc to the binary orbit must be about 70 − 80○ and the inclination of the binary orbit to the line of sight must be similarly high, although restricted to <75○ by the absence of X-ray eclipses.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"24 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139279786","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}
Szilárd Kálmán, Szilárd Csizmadia, Attila Simon E, Kristine W F Lam, Adrien Deline, Jan-Vincent Harre, Gyula Szabó M
Abstract Despite the ever-growing number of exoplanets discovered and the extensive analyses carried out to find their potential satellites, only two exomoon candidates, Kepler-1625b-i and Kepler-1708 b-i, have been discovered to date. A considerable amount of effort has been invested in the development of algorithms for modelling, searching, and detecting exomoons in exoplanetary light curves. In this work, we incorporate moon handling capabilities into the state-of-the-art and publicly available code, the Transit and Light Curve Modeller (TLCM). The code is designed for the analysis of transiting exoplanet systems with the inclusion of a wavelet-based noise handling algorithm. Here we present an updated version of TLCM that is capable of modelling a planet-moon system on an elliptical orbit around its host, while also accounting for mutual eclipses between the two bodies – a so-called photodynamic model.
{"title":"Modelling the Light Curves of Transiting Exomoons: a Zero-order Photodynamic Agent Added to the Transit and Light Curve Modeller","authors":"Szilárd Kálmán, Szilárd Csizmadia, Attila Simon E, Kristine W F Lam, Adrien Deline, Jan-Vincent Harre, Gyula Szabó M","doi":"10.1093/mnrasl/slad169","DOIUrl":"https://doi.org/10.1093/mnrasl/slad169","url":null,"abstract":"Abstract Despite the ever-growing number of exoplanets discovered and the extensive analyses carried out to find their potential satellites, only two exomoon candidates, Kepler-1625b-i and Kepler-1708 b-i, have been discovered to date. A considerable amount of effort has been invested in the development of algorithms for modelling, searching, and detecting exomoons in exoplanetary light curves. In this work, we incorporate moon handling capabilities into the state-of-the-art and publicly available code, the Transit and Light Curve Modeller (TLCM). The code is designed for the analysis of transiting exoplanet systems with the inclusion of a wavelet-based noise handling algorithm. Here we present an updated version of TLCM that is capable of modelling a planet-moon system on an elliptical orbit around its host, while also accounting for mutual eclipses between the two bodies – a so-called photodynamic model.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":" 15","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135291852","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}
Sk Minhajur Rahaman, Jonathan Granot, Paz Beniamini
Abstract Internal shocks are a leading candidate for the dissipation mechanism that powers the prompt γ-ray emission in gamma-ray bursts (GRBs). In this scenario a compact central source produces an ultra-relativistic outflow with varying speeds, causing faster parts or shells to collide with slower ones. Each collision produces a pair of shocks – a forward shock (FS) propagating into the slower leading shell and a reverse shock (RS) propagating into the faster trailing shell. The RS’s lab-frame speed is always smaller, while the RS is typically stronger than the FS, leading to different conditions in the two shocked regions that both contribute to the observed emission. We show that optically-thin synchrotron emission from both (weaker FS + stronger RS) can naturally explain key features of prompt GRB emission such as the pulse shapes, time-evolution of the νFν peak flux and photon-energy, and the spectrum. Particularly, it can account for two features commonly observed in GRB spectra: (i) a sub-dominant low-energy spectral component (often interpreted as “photospheric”-like), or (ii) a doubly-broken power-law spectrum with the low-energy spectral slope approaching the slow cooling limit. Both features can be obtained while maintaining high overall radiative efficiency without any fine-tuning of the physical conditions.
{"title":"Prompt Gamma-Ray Burst Emission from Internal Shocks – New Insights","authors":"Sk Minhajur Rahaman, Jonathan Granot, Paz Beniamini","doi":"10.1093/mnrasl/slad168","DOIUrl":"https://doi.org/10.1093/mnrasl/slad168","url":null,"abstract":"Abstract Internal shocks are a leading candidate for the dissipation mechanism that powers the prompt γ-ray emission in gamma-ray bursts (GRBs). In this scenario a compact central source produces an ultra-relativistic outflow with varying speeds, causing faster parts or shells to collide with slower ones. Each collision produces a pair of shocks – a forward shock (FS) propagating into the slower leading shell and a reverse shock (RS) propagating into the faster trailing shell. The RS’s lab-frame speed is always smaller, while the RS is typically stronger than the FS, leading to different conditions in the two shocked regions that both contribute to the observed emission. We show that optically-thin synchrotron emission from both (weaker FS + stronger RS) can naturally explain key features of prompt GRB emission such as the pulse shapes, time-evolution of the νFν peak flux and photon-energy, and the spectrum. Particularly, it can account for two features commonly observed in GRB spectra: (i) a sub-dominant low-energy spectral component (often interpreted as “photospheric”-like), or (ii) a doubly-broken power-law spectrum with the low-energy spectral slope approaching the slow cooling limit. Both features can be obtained while maintaining high overall radiative efficiency without any fine-tuning of the physical conditions.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"30 7","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135430040","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}
Izotov, Y. I., Schaerer, D., Guseva, N. G., Thuan, T. X., Worseck, G.
Using Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS) observations of one of the most metal-poor dwarf star-forming galaxies (SFG) in the local Universe, J2229+2725, we have discovered an extremely strong nebular CIV 1549, 1551 emission-line doublet, with an equivalent width of 43A, several times higher than the value observed so far in low-redshift SFGs. Together with other extreme characteristics obtained from optical spectroscopy (oxygen abundance 12+log(O/H)=7.085+/-0.031, ratio O32 = I([OIII]5007)/I([OII]3727) ~ 53, and equivalent width of the Hbeta emission line EW(Hbeta) = 577A), this galaxy greatly increases the range of physical properties for dwarf SFGs at low redshift and is a likely analogue of the high-redshift dwarf SFGs responsible for the reionization of the Universe. We find the ionizing radiation in J2229+2725 to be stellar in origin and the high EW(CIV 1549,1551) to be due to both extreme ionization conditions and a high carbon abundance, with a corresponding log C/O = -0.38, that is ~ 0.4 dex higher than the average value for nearby low-metallicity SFGs.
{"title":"Extremely strong C <scp>iv</scp> λ1550 nebular emission in the extremely low-metallicity star-forming galaxy J2229+2725","authors":"Izotov, Y. I., Schaerer, D., Guseva, N. G., Thuan, T. X., Worseck, G.","doi":"10.1093/mnrasl/slad166","DOIUrl":"https://doi.org/10.1093/mnrasl/slad166","url":null,"abstract":"Using Hubble Space Telescope (HST)/Cosmic Origins Spectrograph (COS) observations of one of the most metal-poor dwarf star-forming galaxies (SFG) in the local Universe, J2229+2725, we have discovered an extremely strong nebular CIV 1549, 1551 emission-line doublet, with an equivalent width of 43A, several times higher than the value observed so far in low-redshift SFGs. Together with other extreme characteristics obtained from optical spectroscopy (oxygen abundance 12+log(O/H)=7.085+/-0.031, ratio O32 = I([OIII]5007)/I([OII]3727) ~ 53, and equivalent width of the Hbeta emission line EW(Hbeta) = 577A), this galaxy greatly increases the range of physical properties for dwarf SFGs at low redshift and is a likely analogue of the high-redshift dwarf SFGs responsible for the reionization of the Universe. We find the ionizing radiation in J2229+2725 to be stellar in origin and the high EW(CIV 1549,1551) to be due to both extreme ionization conditions and a high carbon abundance, with a corresponding log C/O = -0.38, that is ~ 0.4 dex higher than the average value for nearby low-metallicity SFGs.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"8 29","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135540472","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}
Abstract High mass X-ray binaries hosting red supergiant (RSG) donors are a rare but crucial phase in massive stellar evolution, with only one source previously known in the Milky Way. In this letter, we present the identification of the second Galactic RSG X-ray binary SWIFT J0850.8-4219. We identify the source 2MASS 08504008-4211514 as the likely infrared counterpart with a chance coincidence probability ≈5 × 10−6. We present a 1.0 − 2.5 μm spectrum of the counterpart, exhibiting features characteristic of late-type stars and an exceptionally strong He I emission line, corroborating the identification. Based on i) the strength of the 12CO(2,0) band, ii) strong CN bandheads and absent TiO bandheads at ≈1.1 μm and iii) equivalent width of the Mg I 1.71 μm line, we classify the counterpart to be a K3−K5 type RSG with an effective temperature of 3820 ± 100 K, located at a distance of ≈12 kpc. We estimate the source X-ray luminosity to be (4 ± 1) × 1035 erg s−1, with a hard photon index (Γ < 1), arguing against a white dwarf accretor but consistent with a magnetized neutron star in the propeller phase. Our results highlight the potential of systematic NIR spectroscopy of Galactic hard X-ray sources in completing our census of the local X-ray binary population.
{"title":"Infrared spectroscopy of SWIFT J0850.8-4219: Identification of the second red supergiant X-ray binary in the Milky Way","authors":"Kishalay De, Fiona A Daly, Roberto Soria","doi":"10.1093/mnrasl/slad164","DOIUrl":"https://doi.org/10.1093/mnrasl/slad164","url":null,"abstract":"Abstract High mass X-ray binaries hosting red supergiant (RSG) donors are a rare but crucial phase in massive stellar evolution, with only one source previously known in the Milky Way. In this letter, we present the identification of the second Galactic RSG X-ray binary SWIFT J0850.8-4219. We identify the source 2MASS 08504008-4211514 as the likely infrared counterpart with a chance coincidence probability ≈5 × 10−6. We present a 1.0 − 2.5 μm spectrum of the counterpart, exhibiting features characteristic of late-type stars and an exceptionally strong He I emission line, corroborating the identification. Based on i) the strength of the 12CO(2,0) band, ii) strong CN bandheads and absent TiO bandheads at ≈1.1 μm and iii) equivalent width of the Mg I 1.71 μm line, we classify the counterpart to be a K3−K5 type RSG with an effective temperature of 3820 ± 100 K, located at a distance of ≈12 kpc. We estimate the source X-ray luminosity to be (4 ± 1) × 1035 erg s−1, with a hard photon index (Γ &lt; 1), arguing against a white dwarf accretor but consistent with a magnetized neutron star in the propeller phase. Our results highlight the potential of systematic NIR spectroscopy of Galactic hard X-ray sources in completing our census of the local X-ray binary population.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"66 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135685125","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}
S A Adil, Ö Akarsu, M Malekjani, E Ó Colgáin, S Pourojaghi, A A Sen, M M Sheikh-Jabbari
Abstract Hubble constant H0 and weighted amplitude of matter fluctuations S8 determinations are biased to higher and lower values, respectively, in the late Universe with respect to early Universe values inferred by the Planck collaboration within flat ΛCDM cosmology. If these anomalies are physical, i.e. not due to systematics, they naively suggest that H0 decreases and S8 increases with effective redshift. Here, subjecting matter density today Ωm to a prior, corresponding to a combination of Planck CMB and BAO data, we perform a consistency test of the Planck-ΛCDM cosmology and show that S8 determinations from fσ8(z) constraints increase with effective redshift. Due to the redshift evolution, a ∼3σ tension in the S8 parameter with Planck at lower redshifts remarkably becomes consistent with Planck within 1σ at high redshifts. This provides corroborating support for an S8 discrepancy that is physical in origin. We further confirm that the flat ΛCDM model is preferred over a theoretically ad hoc model with a jump in S8 at a given redshift. In the absence of the CMB+BAO Ωm prior, we find that >3σ tensions with Planck in low redshift data are ameliorated by shifts in the parameters in high redshift data. Results here and elsewhere suggest that the ΛCDM cosmological parameters are redshift dependent. Fitting parameters that evolve with redshift is a recognisable hallmark of model breakdown.
{"title":"<i>S</i> 8 increases with effective redshift in ΛCDM cosmology","authors":"S A Adil, Ö Akarsu, M Malekjani, E Ó Colgáin, S Pourojaghi, A A Sen, M M Sheikh-Jabbari","doi":"10.1093/mnrasl/slad165","DOIUrl":"https://doi.org/10.1093/mnrasl/slad165","url":null,"abstract":"Abstract Hubble constant H0 and weighted amplitude of matter fluctuations S8 determinations are biased to higher and lower values, respectively, in the late Universe with respect to early Universe values inferred by the Planck collaboration within flat ΛCDM cosmology. If these anomalies are physical, i.e. not due to systematics, they naively suggest that H0 decreases and S8 increases with effective redshift. Here, subjecting matter density today Ωm to a prior, corresponding to a combination of Planck CMB and BAO data, we perform a consistency test of the Planck-ΛCDM cosmology and show that S8 determinations from fσ8(z) constraints increase with effective redshift. Due to the redshift evolution, a ∼3σ tension in the S8 parameter with Planck at lower redshifts remarkably becomes consistent with Planck within 1σ at high redshifts. This provides corroborating support for an S8 discrepancy that is physical in origin. We further confirm that the flat ΛCDM model is preferred over a theoretically ad hoc model with a jump in S8 at a given redshift. In the absence of the CMB+BAO Ωm prior, we find that &gt;3σ tensions with Planck in low redshift data are ameliorated by shifts in the parameters in high redshift data. Results here and elsewhere suggest that the ΛCDM cosmological parameters are redshift dependent. Fitting parameters that evolve with redshift is a recognisable hallmark of model breakdown.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"7 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135874542","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}
ABSTRACT The main goal of our research is to search for super-strong magnetic fields in active processes on the Sun. Our method is based on Stokes V spectro-polarimetry in a wide spectral range from −14 Å to +29 Å relative to the D3 He i line. The object of the study is the area of a seismic source in the large solar flare on 2003 October 28 of the X17.2/4B class. The novelty of our study: we found characteristic spectral manifestations – secondary Stokes V peaks – far from D3 line, at distances of several angstroms. These secondary peaks have the following features: (a) their amplitudes reach 4 per cent – almost an order of magnitude more than previously detected in other flares, (b) in the general picture, the sign of the circular polarization changes when passing through the D3 centre, and (c) narrower spectral peculiarities were found at distances of +4.0, +6.3, and +8.5 Å, where the polarization sign also changes sharply. This unusual feature likely results from significant factors in the area of the seismic source, including substantial descending plasma velocities which exceed 400 km s−1 and, perhaps, super-strong magnetic fields.
我们研究的主要目标是在太阳的活动过程中寻找超强磁场。我们的方法是基于Stokes V光谱偏振法，相对于D3 He i线在−14 Å到+29 Å的宽光谱范围内。研究的对象是2003年10月28日X17.2/4B级大太阳耀斑的震源区域。我们研究的新颖之处在于:我们发现了远离D3线的特征光谱表现——次级斯托克斯V峰，距离为几埃。这些次级峰具有以下特征:(a)它们的振幅达到4% -几乎比以前在其他耀斑中检测到的要多一个数量级;(b)在一般图像中，圆偏振的符号在通过D3中心时发生变化;(c)在距离+4.0，+6.3和+8.5 Å处发现了更窄的光谱特性，其中偏振符号也发生了急剧变化。这种不寻常的特征可能是由震源区域的重要因素造成的，包括大幅下降的等离子体速度超过400 km s - 1，也许还有超强的磁场。
{"title":"Unique spectral manifestations around the D3 line observed in the region close to the seismic source of a large solar flare","authors":"N I Lozitska, I I Yakovkin, V G Lozitsky","doi":"10.1093/mnrasl/slad163","DOIUrl":"https://doi.org/10.1093/mnrasl/slad163","url":null,"abstract":"ABSTRACT The main goal of our research is to search for super-strong magnetic fields in active processes on the Sun. Our method is based on Stokes V spectro-polarimetry in a wide spectral range from −14 Å to +29 Å relative to the D3 He i line. The object of the study is the area of a seismic source in the large solar flare on 2003 October 28 of the X17.2/4B class. The novelty of our study: we found characteristic spectral manifestations – secondary Stokes V peaks – far from D3 line, at distances of several angstroms. These secondary peaks have the following features: (a) their amplitudes reach 4 per cent – almost an order of magnitude more than previously detected in other flares, (b) in the general picture, the sign of the circular polarization changes when passing through the D3 centre, and (c) narrower spectral peculiarities were found at distances of +4.0, +6.3, and +8.5 Å, where the polarization sign also changes sharply. This unusual feature likely results from significant factors in the area of the seismic source, including substantial descending plasma velocities which exceed 400 km s−1 and, perhaps, super-strong magnetic fields.","PeriodicalId":18951,"journal":{"name":"Monthly Notices of the Royal Astronomical Society: Letters","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135874367","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}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：