Mattia C Sormani, Emanuele Sobacchi, Jason L Sanders
Gaseous nuclear rings are large-scale coherent structures commonly found at the centres of barred galaxies. We propose that they are an accumulation of gas at the inner edge of an extensive gap that forms around the Inner Lindblad Resonance (ILR). The gap initially opens because the bar potential excites strong trailing waves near the ILR, which remove angular momentum from the gas disc and transport the gas inwards. The gap then widens because the bar potential continuously excites trailing waves at the inner edge of the gap, which remove further angular momentum, moving the edge further inwards until it stops at a distance of several wavelengths from the ILR. The gas accumulating at the inner edge of the gap forms the nuclear ring. The speed at which the gap edge moves and its final distance from the ILR strongly depend on the sound speed, explaining the puzzling dependence of the nuclear ring radius on the sound speed in simulations.
{"title":"Nuclear rings are the inner edge of a gap around the Lindblad Resonance","authors":"Mattia C Sormani, Emanuele Sobacchi, Jason L Sanders","doi":"10.1093/mnras/stae082","DOIUrl":"https://doi.org/10.1093/mnras/stae082","url":null,"abstract":"Gaseous nuclear rings are large-scale coherent structures commonly found at the centres of barred galaxies. We propose that they are an accumulation of gas at the inner edge of an extensive gap that forms around the Inner Lindblad Resonance (ILR). The gap initially opens because the bar potential excites strong trailing waves near the ILR, which remove angular momentum from the gas disc and transport the gas inwards. The gap then widens because the bar potential continuously excites trailing waves at the inner edge of the gap, which remove further angular momentum, moving the edge further inwards until it stops at a distance of several wavelengths from the ILR. The gas accumulating at the inner edge of the gap forms the nuclear ring. The speed at which the gap edge moves and its final distance from the ILR strongly depend on the sound speed, explaining the puzzling dependence of the nuclear ring radius on the sound speed in simulations.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"4 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139481780","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}
Masaya Yamamoto, Katherine Laliotis, Emily Macbeth, Tianqing Zhang, Christopher M Hirata, M A Troxel, Kaili Cao, Ami Choi, Jahmour Givans, Katrin Heitmann, Mustapha Ishak, Mike Jarvis, Eve Kovacs, Heyang Long, Rachel Mandelbaum, Andy Park, Anna Porredon, Christopher W Walter, W Michael Wood-Vasey
One challenge for applying current weak lensing analysis tools to the Nancy Grace Roman Space Telescope is that individual images will be undersampled. Our companion paper presented an initial application of Imcom — an algorithm that builds an optimal mapping from input to output pixels to reconstruct a fully sampled combined image — on the Roman image simulations. In this paper, we measure the output noise power spectra, identify the sources of the major features in the power spectra, and show that simple analytic models that ignore sampling effects underestimate the power spectra of the coadded noise images. We compute the moments of both idealized injected stars and fully simulated stars in the coadded images, and their 1- and 2-point statistics. We show that the idealized injected stars have root-mean-square ellipticity errors (1 − 6) × 10−4 per component depending on the band; the correlation functions are ≥2 orders of magnitude below requirements, indicating that the image combination step itself is using a small fraction of the overall Roman 2nd moment error budget, although the 4th moments are larger and warrant further investigation. The stars in the simulated sky images, which include blending and chromaticity effects, have correlation functions near the requirement level (and below the requirement level in a wide-band image constructed by stacking all 4 filters). We evaluate the noise-induced biases in the ellipticities of injected stars, and explain the resulting trends with an analytical model. We conclude by enumerating the next steps in developing an image coaddition pipeline for Roman.
{"title":"Simulating image coaddition with the Nancy Grace Roman Space Telescope: II. Analysis of the simulated images and implications for weak lensing","authors":"Masaya Yamamoto, Katherine Laliotis, Emily Macbeth, Tianqing Zhang, Christopher M Hirata, M A Troxel, Kaili Cao, Ami Choi, Jahmour Givans, Katrin Heitmann, Mustapha Ishak, Mike Jarvis, Eve Kovacs, Heyang Long, Rachel Mandelbaum, Andy Park, Anna Porredon, Christopher W Walter, W Michael Wood-Vasey","doi":"10.1093/mnras/stae177","DOIUrl":"https://doi.org/10.1093/mnras/stae177","url":null,"abstract":"One challenge for applying current weak lensing analysis tools to the Nancy Grace Roman Space Telescope is that individual images will be undersampled. Our companion paper presented an initial application of Imcom — an algorithm that builds an optimal mapping from input to output pixels to reconstruct a fully sampled combined image — on the Roman image simulations. In this paper, we measure the output noise power spectra, identify the sources of the major features in the power spectra, and show that simple analytic models that ignore sampling effects underestimate the power spectra of the coadded noise images. We compute the moments of both idealized injected stars and fully simulated stars in the coadded images, and their 1- and 2-point statistics. We show that the idealized injected stars have root-mean-square ellipticity errors (1 − 6) × 10−4 per component depending on the band; the correlation functions are ≥2 orders of magnitude below requirements, indicating that the image combination step itself is using a small fraction of the overall Roman 2nd moment error budget, although the 4th moments are larger and warrant further investigation. The stars in the simulated sky images, which include blending and chromaticity effects, have correlation functions near the requirement level (and below the requirement level in a wide-band image constructed by stacking all 4 filters). We evaluate the noise-induced biases in the ellipticities of injected stars, and explain the resulting trends with an analytical model. We conclude by enumerating the next steps in developing an image coaddition pipeline for Roman.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"30 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482071","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}
Amelie K Read, Timothy R Bedding, Prasad Mani, Benjamin T Montet, Courtney Crawford, Daniel R Hey, Yaguang Li (), Simon J Murphy, May Gade Pedersen, Joachim Kruger
We use TESS 10-minute Full Frame Images (Sectors 27–55) to study a sample of 1708 stars within 500 pc of the Sun that lie in a narrow colour range in the centre of the δ Scuti instability strip (0.29 < GBP − GRP < 0.31). Based on the Fourier amplitude spectra, we identify 848 δ Scuti stars, as well as 47 eclipsing or contact binaries. The strongest pulsation modes of some δ Scuti stars fall on the period–luminosity relation of the fundamental radial mode but many correspond to overtones that are approximately a factor of two higher in frequency. Many of the low-luminosity δ Scuti stars show a series of high-frequency modes with very regular spacings. The fraction of stars in our sample that show δ Scuti pulsations is about 70 per cent for the brightest stars (G < 8), consistent with results from Kepler. However, the fraction drops to about 45 per cent for fainter stars and we find that a single sector of TESS data only detects the lowest-amplitude δ Scuti pulsations (around 50 ppm) in stars down to about G = 9. Finally, we have found four new high-frequency δ Scuti stars with very regular mode patterns, and have detected pulsations in λ Mus that make it the fourth-brightest δ Scuti in the sky (G = 3.63). Overall, these results confirm the power of TESS and Gaia for studying pulsating stars.
{"title":"Identifying 850 δ Scuti pulsators in a narrow Gaia colour range with TESS 10-minute full-frame images","authors":"Amelie K Read, Timothy R Bedding, Prasad Mani, Benjamin T Montet, Courtney Crawford, Daniel R Hey, Yaguang Li (), Simon J Murphy, May Gade Pedersen, Joachim Kruger","doi":"10.1093/mnras/stae165","DOIUrl":"https://doi.org/10.1093/mnras/stae165","url":null,"abstract":"We use TESS 10-minute Full Frame Images (Sectors 27–55) to study a sample of 1708 stars within 500 pc of the Sun that lie in a narrow colour range in the centre of the δ Scuti instability strip (0.29 &lt; GBP − GRP &lt; 0.31). Based on the Fourier amplitude spectra, we identify 848 δ Scuti stars, as well as 47 eclipsing or contact binaries. The strongest pulsation modes of some δ Scuti stars fall on the period–luminosity relation of the fundamental radial mode but many correspond to overtones that are approximately a factor of two higher in frequency. Many of the low-luminosity δ Scuti stars show a series of high-frequency modes with very regular spacings. The fraction of stars in our sample that show δ Scuti pulsations is about 70 per cent for the brightest stars (G &lt; 8), consistent with results from Kepler. However, the fraction drops to about 45 per cent for fainter stars and we find that a single sector of TESS data only detects the lowest-amplitude δ Scuti pulsations (around 50 ppm) in stars down to about G = 9. Finally, we have found four new high-frequency δ Scuti stars with very regular mode patterns, and have detected pulsations in λ Mus that make it the fourth-brightest δ Scuti in the sky (G = 3.63). Overall, these results confirm the power of TESS and Gaia for studying pulsating stars.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"30 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139484218","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}
Strong gravitational lensing can be used to find otherwise invisible dark matter subhaloes. In such an analysis, the lens galaxy mass model is a significant source of systematic uncertainty. In this paper we analyse the effect of angular complexity in the lens model. We use multipole perturbations which introduce low-order deviations from pure ellipticity in the isodensity contours, keeping the radial density profile fixed. We find that, in HST-like data, multipole perturbations consistent with those seen in galaxy isophotes are very effective at causing false positive substructure detections. We show that the effectiveness of this degeneracy depends on the deviation from a pure ellipse and the lensing configuration. We find that, when multipoles of one per cent are allowed in the lens model, the area in the observation where a subhalo could be detected drops by a factor of three. Sensitivity away from the lensed images is mostly lost. However, the mass limit of detectable objects on or close to the lensed images does not change. We do not expect the addition of multipole perturbations to lens models to have a significant effect on the ability of strong lensing to constrain the underlying dark matter model. However, given the high rate of false positive detections, angular complexity beyond the elliptical power-law should be included for such studies to be reliable. We discuss implications for previous detections and future work.
{"title":"Angular complexity in strong lens substructure detection","authors":"Conor M O’Riordan, Simona Vegetti","doi":"10.1093/mnras/stae153","DOIUrl":"https://doi.org/10.1093/mnras/stae153","url":null,"abstract":"Strong gravitational lensing can be used to find otherwise invisible dark matter subhaloes. In such an analysis, the lens galaxy mass model is a significant source of systematic uncertainty. In this paper we analyse the effect of angular complexity in the lens model. We use multipole perturbations which introduce low-order deviations from pure ellipticity in the isodensity contours, keeping the radial density profile fixed. We find that, in HST-like data, multipole perturbations consistent with those seen in galaxy isophotes are very effective at causing false positive substructure detections. We show that the effectiveness of this degeneracy depends on the deviation from a pure ellipse and the lensing configuration. We find that, when multipoles of one per cent are allowed in the lens model, the area in the observation where a subhalo could be detected drops by a factor of three. Sensitivity away from the lensed images is mostly lost. However, the mass limit of detectable objects on or close to the lensed images does not change. We do not expect the addition of multipole perturbations to lens models to have a significant effect on the ability of strong lensing to constrain the underlying dark matter model. However, given the high rate of false positive detections, angular complexity beyond the elliptical power-law should be included for such studies to be reliable. We discuss implications for previous detections and future work.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"34 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482062","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}
Yuta Murai, Masaomi Tanaka, Miho Kawabata, Kenta Taguchi, Rishabh Singh Teja, Tatsuya Nakaoka, Keiichi Maeda, Koji S Kawabata, Takashi Nagao, Takashi J Moriya, D K Sahu, G C Anupama, Nozomu Tominaga, Tomoki Morokuma, Ryo Imazawa, Satoko Inutsuka, Keisuke Isogai, Toshihiro Kasuga, Naoto Kobayashi, Sohei Kondo, Hiroyuki Maehara, Yuki Mori, Yuu Niino, Mao Ogawa, Ryou Ohsawa, Shin-ichiro Okumura, Sei Saito, Shigeyuki Sako, Hidenori Takahashi, Kohki Uno, Masayuki Yamanaka
We present photometric, spectroscopic and polarimetric observations of the intermediate-luminosity Type IIP supernova (SN) 2021gmj from 1 to 386 days after the explosion. The peak absolute V-band magnitude of SN 2021gmj is −15.5 mag, which is fainter than that of normal Type IIP SNe. The spectral evolution of SN 2021gmj resembles that of other sub-luminous supernovae: the optical spectra show narrow P-Cygni profiles, indicating a low expansion velocity. We estimate the progenitor mass to be about 12 $rm M_{odot }$ from the nebular spectrum and the 56Ni mass to be about 0.02 $rm M_{odot }$ from the bolometric light curve. We also derive the explosion energy to be about 3 × 1050 erg by comparing numerical light curve models with the observed light curves. Polarization in the plateau phase is not very large, suggesting nearly spherical outer envelope. The early photometric observations capture the rapid rise of the light curve, which is likely due to the interaction with a circumstellar material (CSM). The broad emission feature formed by highly-ionized lines on top of a blue continuum in the earliest spectrum gives further indication of the CSM at the vicinity of the progenitor. Our work suggests that a relatively low-mass progenitor of an intermediate-luminosity Type IIP SN can also experience an enhanced mass loss just before the explosion, as suggested for normal Type IIP SNe.
{"title":"Intermediate-luminosity Type IIP SN 2021gmj: A low-energy explosion with signatures of circumstellar material","authors":"Yuta Murai, Masaomi Tanaka, Miho Kawabata, Kenta Taguchi, Rishabh Singh Teja, Tatsuya Nakaoka, Keiichi Maeda, Koji S Kawabata, Takashi Nagao, Takashi J Moriya, D K Sahu, G C Anupama, Nozomu Tominaga, Tomoki Morokuma, Ryo Imazawa, Satoko Inutsuka, Keisuke Isogai, Toshihiro Kasuga, Naoto Kobayashi, Sohei Kondo, Hiroyuki Maehara, Yuki Mori, Yuu Niino, Mao Ogawa, Ryou Ohsawa, Shin-ichiro Okumura, Sei Saito, Shigeyuki Sako, Hidenori Takahashi, Kohki Uno, Masayuki Yamanaka","doi":"10.1093/mnras/stae170","DOIUrl":"https://doi.org/10.1093/mnras/stae170","url":null,"abstract":"We present photometric, spectroscopic and polarimetric observations of the intermediate-luminosity Type IIP supernova (SN) 2021gmj from 1 to 386 days after the explosion. The peak absolute V-band magnitude of SN 2021gmj is −15.5 mag, which is fainter than that of normal Type IIP SNe. The spectral evolution of SN 2021gmj resembles that of other sub-luminous supernovae: the optical spectra show narrow P-Cygni profiles, indicating a low expansion velocity. We estimate the progenitor mass to be about 12 $rm M_{odot }$ from the nebular spectrum and the 56Ni mass to be about 0.02 $rm M_{odot }$ from the bolometric light curve. We also derive the explosion energy to be about 3 × 1050 erg by comparing numerical light curve models with the observed light curves. Polarization in the plateau phase is not very large, suggesting nearly spherical outer envelope. The early photometric observations capture the rapid rise of the light curve, which is likely due to the interaction with a circumstellar material (CSM). The broad emission feature formed by highly-ionized lines on top of a blue continuum in the earliest spectrum gives further indication of the CSM at the vicinity of the progenitor. Our work suggests that a relatively low-mass progenitor of an intermediate-luminosity Type IIP SN can also experience an enhanced mass loss just before the explosion, as suggested for normal Type IIP SNe.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"14 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482319","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 present a comparative study of the constrained parameters of active galactic nuclei (AGN) made by the public X-ray reverberation model kynxilrev and kynrefrev that make use of the reflection code xillver and reflionx, respectively. By varying the central mass (MBH), coronal height (h), inclination (i), photon index of the continuum emission (Γ) and source luminosity (L), the corresponding lag-frequency spectra can be produced. We select only the simulated AGN where their lag amplitude (τ) and MBH follow the known mass-scaling law. In these mock samples, we show that τ and h are correlated and can possibly be used as an independent scaling law. Furthermore, h (in gravitational units) is also found to be positively scaled with MBH, suggesting a more compact corona in lower-mass AGN. Both models reveal that the coronal height mostly varies between ∼5–15 rg, with the average height at ∼10 rg and can potentially be found from low- to high-mass AGN. Nevertheless, the kynxilrev seems to suggest a lower MBH and h than the kynrefrev. This inconsistency is more prominent in lower-spin AGN. The significant correlation between the source height and luminosity is revealed only by kynrefrev, suggesting the h–L relation is probably model dependent. Our findings emphasize the differences between these reverberation models that raises the question of biases in parameter estimates and inferred correlations.
{"title":"Parameter dependency on the public X-ray reverberation models kynxilrev and kynrefrev","authors":"K Khanthasombat, P Chainakun, A J Young","doi":"10.1093/mnras/stae173","DOIUrl":"https://doi.org/10.1093/mnras/stae173","url":null,"abstract":"We present a comparative study of the constrained parameters of active galactic nuclei (AGN) made by the public X-ray reverberation model kynxilrev and kynrefrev that make use of the reflection code xillver and reflionx, respectively. By varying the central mass (MBH), coronal height (h), inclination (i), photon index of the continuum emission (Γ) and source luminosity (L), the corresponding lag-frequency spectra can be produced. We select only the simulated AGN where their lag amplitude (τ) and MBH follow the known mass-scaling law. In these mock samples, we show that τ and h are correlated and can possibly be used as an independent scaling law. Furthermore, h (in gravitational units) is also found to be positively scaled with MBH, suggesting a more compact corona in lower-mass AGN. Both models reveal that the coronal height mostly varies between ∼5–15 rg, with the average height at ∼10 rg and can potentially be found from low- to high-mass AGN. Nevertheless, the kynxilrev seems to suggest a lower MBH and h than the kynrefrev. This inconsistency is more prominent in lower-spin AGN. The significant correlation between the source height and luminosity is revealed only by kynrefrev, suggesting the h–L relation is probably model dependent. Our findings emphasize the differences between these reverberation models that raises the question of biases in parameter estimates and inferred correlations.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"6 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139481777","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}
Chunxiang Wang, Ran Li, Huanyuan Shan, Weiwei Xu, Ji Yao, Yingjie Jing, Liang Gao, Nan Li, Yushan Xie, Kai Zhu, Hang Yang, Qingze Chen
The galaxy-galaxy lensing technique allows us to measure the subhalo mass of satellite galaxies, studying their mass loss and evolution within galaxy clusters and providing direct observational validation for theories of galaxy formation. In this study, we use the weak gravitational lensing observations from DECaLS DR8, in combination with the redMaPPer galaxy cluster catalog from SDSS DR8 to accurately measure the dark matter halo mass of satellite galaxies. We confirm a significant increase in the stellar-to-halo mass ratio of satellite galaxies with their halo-centric radius, indicating clear evidence of mass loss due to tidal stripping. Additionally, we find that this mass loss is strongly dependent on the mass of the satellite galaxies, with satellite galaxies above 1011 M⊙ h−1 experiencing more pronounced mass loss compared to lower mass satellites, reaching 86 per cent at projected halo-centric radius 0.5R200c. The average mass loss rate, when not considering halo-centric radius, displays a U-shaped variation with stellar mass, with galaxies of approximately 4 × 1010 M⊙ h−1 exhibiting the least mass loss, around 60 per cent. We compare our results with state-of-the-art hydrodynamical numerical simulations and find that the satellite galaxy stellar-to-halo mass ratio in the outskirts of galaxy clusters is higher compared to the predictions of the Illustris-TNG project about factor 5. Furthermore, the Illustris-TNG project’s numerical simulations did not predict the observed dependence of satellite galaxy mass loss rate on satellite galaxy mass.
{"title":"Assessing mass loss and stellar-to-halo mass ratio of satellite galaxies: A galaxy-galaxy lensing approach utilizing DECaLS DR8 data","authors":"Chunxiang Wang, Ran Li, Huanyuan Shan, Weiwei Xu, Ji Yao, Yingjie Jing, Liang Gao, Nan Li, Yushan Xie, Kai Zhu, Hang Yang, Qingze Chen","doi":"10.1093/mnras/stae121","DOIUrl":"https://doi.org/10.1093/mnras/stae121","url":null,"abstract":"The galaxy-galaxy lensing technique allows us to measure the subhalo mass of satellite galaxies, studying their mass loss and evolution within galaxy clusters and providing direct observational validation for theories of galaxy formation. In this study, we use the weak gravitational lensing observations from DECaLS DR8, in combination with the redMaPPer galaxy cluster catalog from SDSS DR8 to accurately measure the dark matter halo mass of satellite galaxies. We confirm a significant increase in the stellar-to-halo mass ratio of satellite galaxies with their halo-centric radius, indicating clear evidence of mass loss due to tidal stripping. Additionally, we find that this mass loss is strongly dependent on the mass of the satellite galaxies, with satellite galaxies above 1011 M⊙ h−1 experiencing more pronounced mass loss compared to lower mass satellites, reaching 86 per cent at projected halo-centric radius 0.5R200c. The average mass loss rate, when not considering halo-centric radius, displays a U-shaped variation with stellar mass, with galaxies of approximately 4 × 1010 M⊙ h−1 exhibiting the least mass loss, around 60 per cent. We compare our results with state-of-the-art hydrodynamical numerical simulations and find that the satellite galaxy stellar-to-halo mass ratio in the outskirts of galaxy clusters is higher compared to the predictions of the Illustris-TNG project about factor 5. Furthermore, the Illustris-TNG project’s numerical simulations did not predict the observed dependence of satellite galaxy mass loss rate on satellite galaxy mass.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"45 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482001","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}
Weak gravitational lensing of distant galaxies provides a powerful probe of dark energy. The aim of this study is to investigate the application of convolutional neural networks (CNNs) to precision shear estimation. In particular, using a shallow CNN, we explore the impact of point spread function (PSF) misestimation and ‘galaxy population bias’ (including ‘distribution bias’ and ‘morphology bias’), focusing on the accuracy requirements of next generation surveys. We simulate a population of noisy disk and elliptical galaxies and adopt a PSF that is representative of a Euclid-like survey. We quantify the accuracy achieved by the CNN assuming a linear relationship between the estimated and true shears and measure the multiplicative (m) and additive (c) biases. We make use of an unconventional loss function to mitigate the effects of noise bias and measure m and c when we use either: (i) an incorrect galaxy ellipticity distribution or size–magnitude relation, or the wrong ratio of morphological types, to describe the population of galaxies (distribution bias); (ii) an incorrect galaxy light profile (morphology bias); or (iii) a PSF with size or ellipticity offset from its true value (PSF misestimation). We compare our results to the Euclid requirements on the knowledge of the PSF model shape and size. Finally, we outline further work to build on the promising potential of CNNs in precision shear estimation.
{"title":"Impact of PSF misestimation and galaxy population bias on precision shear measurement using a CNN","authors":"L M Voigt","doi":"10.1093/mnras/stae038","DOIUrl":"https://doi.org/10.1093/mnras/stae038","url":null,"abstract":"Weak gravitational lensing of distant galaxies provides a powerful probe of dark energy. The aim of this study is to investigate the application of convolutional neural networks (CNNs) to precision shear estimation. In particular, using a shallow CNN, we explore the impact of point spread function (PSF) misestimation and ‘galaxy population bias’ (including ‘distribution bias’ and ‘morphology bias’), focusing on the accuracy requirements of next generation surveys. We simulate a population of noisy disk and elliptical galaxies and adopt a PSF that is representative of a Euclid-like survey. We quantify the accuracy achieved by the CNN assuming a linear relationship between the estimated and true shears and measure the multiplicative (m) and additive (c) biases. We make use of an unconventional loss function to mitigate the effects of noise bias and measure m and c when we use either: (i) an incorrect galaxy ellipticity distribution or size–magnitude relation, or the wrong ratio of morphological types, to describe the population of galaxies (distribution bias); (ii) an incorrect galaxy light profile (morphology bias); or (iii) a PSF with size or ellipticity offset from its true value (PSF misestimation). We compare our results to the Euclid requirements on the knowledge of the PSF model shape and size. Finally, we outline further work to build on the promising potential of CNNs in precision shear estimation.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"11 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139482069","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 R Taylor, S Sekhar, L Heino, A M M Scaife, J Stil, M Bowles, M Jarvis, I Heywood, J D Collier
The MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) is one of the MeerKAT large survey projects, designed to pathfind SKA key science. MIGHTEE is undertaking deep radio imaging of four well observed fields (COSMOS, XMM-LSS, ELAIS S1 and CDFS) totaling 20 square degrees to μJy sensitivities. Broadband imaging observations between 880–1690 MHz yield total intensity continuum, spectro-polarimetry, and atomic hydrogen spectral imaging. Early science data from MIGHTEE are being released from initial observations of COSMOS and XMM-LSS. This paper describes the spectro-polarimetric observations, the polarization data processing of the MIGHTEE early science fields, and presents polarization data images and catalogues. The catalogues include radio spectral index, redshift information and Faraday rotation measure synthesis results for 13,267 total intensity radio sources down to a polarized intensity detection limit of ∼20 μJy bm−1. Polarized signals were detected from 324 sources. For the polarized detections we include a catalogue of Faraday Depth from both Faraday Synthesis and Q, U fitting, as well as total intensity and polarization spectral indices. The distribution of redshift of the total radio sources and detected polarized sources are the same, with median redshifts of 0.86 and 0.82 respectively. Depolarization of the emission at longer-wavelengths is seen to increase with decreasing total-intensity spectral index, implying that depolarisation is intrinsic to the radio sources. No evidence is seen for a redshift dependence of the variance of Faraday Depth.
{"title":"MIGHTEE polarization early science fields: The deep polarized sky","authors":"A R Taylor, S Sekhar, L Heino, A M M Scaife, J Stil, M Bowles, M Jarvis, I Heywood, J D Collier","doi":"10.1093/mnras/stae169","DOIUrl":"https://doi.org/10.1093/mnras/stae169","url":null,"abstract":"The MeerKAT International GigaHertz Tiered Extragalactic Exploration (MIGHTEE) is one of the MeerKAT large survey projects, designed to pathfind SKA key science. MIGHTEE is undertaking deep radio imaging of four well observed fields (COSMOS, XMM-LSS, ELAIS S1 and CDFS) totaling 20 square degrees to μJy sensitivities. Broadband imaging observations between 880–1690 MHz yield total intensity continuum, spectro-polarimetry, and atomic hydrogen spectral imaging. Early science data from MIGHTEE are being released from initial observations of COSMOS and XMM-LSS. This paper describes the spectro-polarimetric observations, the polarization data processing of the MIGHTEE early science fields, and presents polarization data images and catalogues. The catalogues include radio spectral index, redshift information and Faraday rotation measure synthesis results for 13,267 total intensity radio sources down to a polarized intensity detection limit of ∼20 μJy bm−1. Polarized signals were detected from 324 sources. For the polarized detections we include a catalogue of Faraday Depth from both Faraday Synthesis and Q, U fitting, as well as total intensity and polarization spectral indices. The distribution of redshift of the total radio sources and detected polarized sources are the same, with median redshifts of 0.86 and 0.82 respectively. Depolarization of the emission at longer-wavelengths is seen to increase with decreasing total-intensity spectral index, implying that depolarisation is intrinsic to the radio sources. No evidence is seen for a redshift dependence of the variance of Faraday Depth.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"18 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139481983","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}
As the reconstruction of the star-formation histories (SFH) of galaxies from spectroscopic data becomes increasingly popular, we explore the best age resolution achievable with stellar population synthesis (SPS) models, relying on different constraints: broad-band colours, absorption indices, a combination of the two, and the full spectrum. We perform idealized experiments on SPS models and show that the minimum resolvable relative duration of a star-formation episode (time difference between 10% and 90% of the stellar mass formed divided by the median age) is never better than 0.4, even when using spectra with signal-to-noise ratio (SNR) larger than 100 per Å. Typically, the best relative age resolution ranges between 0.4 and 0.7 over most of the age-metallicity plane, corresponding to minimum bin sizes for SFH sampling between 0.15 and 0.25 dex. This resolution makes the spectroscopic exploration of distant galaxies mandatory in order to reconstruct the early phases of galaxies’ SFHs. We show that spectroscopy with SNR ≳ 20 Å−1 is essential for good age resolution. Remarkably, using the full spectrum does not prove significantly more effective than relying on absorption indices, especially at SNR ≲ 20 Å−1. We discuss the physical origins of the age resolution trends as a function of age and metallicity, and identify the presence of maxima in age resolution (i.e. minima in measurable relative time duration) at the characteristic ages that correspond to quick time variations in spectral absorption features. We connect these maxima to bumps commonly observed in reconstructed SFHs.
{"title":"On the maximum age resolution achievable through stellar population synthesis models","authors":"Stefano Zibetti, Edoardo Rossi, Anna R Gallazzi","doi":"10.1093/mnras/stae178","DOIUrl":"https://doi.org/10.1093/mnras/stae178","url":null,"abstract":"As the reconstruction of the star-formation histories (SFH) of galaxies from spectroscopic data becomes increasingly popular, we explore the best age resolution achievable with stellar population synthesis (SPS) models, relying on different constraints: broad-band colours, absorption indices, a combination of the two, and the full spectrum. We perform idealized experiments on SPS models and show that the minimum resolvable relative duration of a star-formation episode (time difference between 10% and 90% of the stellar mass formed divided by the median age) is never better than 0.4, even when using spectra with signal-to-noise ratio (SNR) larger than 100 per Å. Typically, the best relative age resolution ranges between 0.4 and 0.7 over most of the age-metallicity plane, corresponding to minimum bin sizes for SFH sampling between 0.15 and 0.25 dex. This resolution makes the spectroscopic exploration of distant galaxies mandatory in order to reconstruct the early phases of galaxies’ SFHs. We show that spectroscopy with SNR ≳ 20 Å−1 is essential for good age resolution. Remarkably, using the full spectrum does not prove significantly more effective than relying on absorption indices, especially at SNR ≲ 20 Å−1. We discuss the physical origins of the age resolution trends as a function of age and metallicity, and identify the presence of maxima in age resolution (i.e. minima in measurable relative time duration) at the characteristic ages that correspond to quick time variations in spectral absorption features. We connect these maxima to bumps commonly observed in reconstructed SFHs.","PeriodicalId":18930,"journal":{"name":"Monthly Notices of the Royal Astronomical Society","volume":"121 1","pages":""},"PeriodicalIF":4.8,"publicationDate":"2024-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139481999","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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