Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/061
Arghyajit Datta, Shaaban Khalil, Rajat Kumar Mandal and Arunansu Sil
We investigate a non-instantaneous reheating period in the early Universe, where the inflaton field decays exclusively to right-handed neutrinos (RHNs). The subsequent decay of these RHNs into Standard Model particles not only drives the transition to a radiation-dominated era but also generates the baryon asymmetry of the Universe via leptogenesis. In this typical reheating scenario, gravitational waves (GWs) can be produced during inflaton decay, both through bremsstrahlung and inflaton scattering processes. While GW production via bremsstrahlung dominates near the end of the reheating phase, inflaton scattering leads to a non-negligible GW contribution near the maximum temperature of the Universe. The combined GW spectrum from both decay and scattering processes lies within the sensitivity range of proposed resonant cavity experiments. This framework thus offers a compelling and unified approach to addressing neutrino mass generation, the baryon asymmetry of the Universe via leptogenesis, and probing the dynamics of a non-instantaneous reheating era.
{"title":"Probing right handed neutrino assisted reheating with gravitational waves and leptogenesis","authors":"Arghyajit Datta, Shaaban Khalil, Rajat Kumar Mandal and Arunansu Sil","doi":"10.1088/1475-7516/2026/02/061","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/061","url":null,"abstract":"We investigate a non-instantaneous reheating period in the early Universe, where the inflaton field decays exclusively to right-handed neutrinos (RHNs). The subsequent decay of these RHNs into Standard Model particles not only drives the transition to a radiation-dominated era but also generates the baryon asymmetry of the Universe via leptogenesis. In this typical reheating scenario, gravitational waves (GWs) can be produced during inflaton decay, both through bremsstrahlung and inflaton scattering processes. While GW production via bremsstrahlung dominates near the end of the reheating phase, inflaton scattering leads to a non-negligible GW contribution near the maximum temperature of the Universe. The combined GW spectrum from both decay and scattering processes lies within the sensitivity range of proposed resonant cavity experiments. This framework thus offers a compelling and unified approach to addressing neutrino mass generation, the baryon asymmetry of the Universe via leptogenesis, and probing the dynamics of a non-instantaneous reheating era.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"38 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205628","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/065
Jianzhuo Li, Yi Zheng and Weishan Zhu
We investigate the distribution of missing baryons in the cosmic filaments by stacking ∼ 30,700 filaments across the northern and southern SDSS sky regions using Planck Compton-y and CMB lensing maps. Filaments are identified using the DisPerSE algorithm applied to the SDSS LOWZ-CMASS galaxy samples, selecting structures with lengths between 30–100 cMpc and redshifts in the range 0.2 < z < 0.6. Radial profiles are extracted out to 25 cMpc from the filament spines, and galaxy clusters with halo masses above ∼ 3 × 1013M⊙ are masked to reduce contamination. We detect the thermal Sunyaev-Zel'dovich (tSZ) signal at 7.82σ and the CMB lensing signal at 7.78σ. The stacked profiles are corrected by a geometric bias correction based on filament inclination with respect to the line-of-sight, and they are portrayed assuming isothermal, cylindrically symmetric models. We explore different gas and matter density distributions, focusing on the β-models with (α,β) = (2,2/3) or (1,1). By jointly fitting the Compton-y and κ profiles, we constrain the central electron overdensity and temperature to be δ = 4.18+2.01-1.06 and Te = 2.74+0.65-0.53 × 106 K for the standard β-model. These results suggest that filamentary WHIM in our selected long filaments contributes a significant baryon fraction of 0.127+0.019-0.021 × Ωb to the cosmic baryon budget.
{"title":"Tracing missing baryons in the cosmic filaments with tSZ and CMB-lensing stacking","authors":"Jianzhuo Li, Yi Zheng and Weishan Zhu","doi":"10.1088/1475-7516/2026/02/065","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/065","url":null,"abstract":"We investigate the distribution of missing baryons in the cosmic filaments by stacking ∼ 30,700 filaments across the northern and southern SDSS sky regions using Planck Compton-y and CMB lensing maps. Filaments are identified using the DisPerSE algorithm applied to the SDSS LOWZ-CMASS galaxy samples, selecting structures with lengths between 30–100 cMpc and redshifts in the range 0.2 < z < 0.6. Radial profiles are extracted out to 25 cMpc from the filament spines, and galaxy clusters with halo masses above ∼ 3 × 1013M⊙ are masked to reduce contamination. We detect the thermal Sunyaev-Zel'dovich (tSZ) signal at 7.82σ and the CMB lensing signal at 7.78σ. The stacked profiles are corrected by a geometric bias correction based on filament inclination with respect to the line-of-sight, and they are portrayed assuming isothermal, cylindrically symmetric models. We explore different gas and matter density distributions, focusing on the β-models with (α,β) = (2,2/3) or (1,1). By jointly fitting the Compton-y and κ profiles, we constrain the central electron overdensity and temperature to be δ = 4.18+2.01-1.06 and Te = 2.74+0.65-0.53 × 106 K for the standard β-model. These results suggest that filamentary WHIM in our selected long filaments contributes a significant baryon fraction of 0.127+0.019-0.021 × Ωb to the cosmic baryon budget.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"76 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/059
Lucas Kuhn, Zack Li and William R. Coulton
The Sunyaev-Zeldovich (SZ) effect is a window into the astrophysical processes of galaxy clusters, and relativistic corrections (the “rSZ”) promise to provide a global census of the gas feedback within clusters. Upcoming wide-field millimeter-wave surveys such as the Simons Observatory (SO), Fred Young Submillimeter Telescope, and CMB-S4 will make increasingly precise measurements of the SZ effect and its relativistic corrections. We present simulated full-sky maps of the rSZ effect and a fast code to generate it, for use in the development of analysis techniques and pipelines. As part of the websky simulation suite, our mock observations have semi-realistic cross-correlations with other large-scale structure tracers, offering insights into the formation and evolution of galaxy clusters and large-scale structure. As a demonstration of this, we examine what an SO-like experiment can learn from the rSZ effect. We find that high significance detections will be possible, provided that the instrumental systematics are under control, and that the evolution of cluster temperatures with mass and redshift can be probed in a manner complementary to X-ray measurements.
{"title":"Forecasts and simulations for relativistic corrections to the Sunyaev-Zeldovich effect","authors":"Lucas Kuhn, Zack Li and William R. Coulton","doi":"10.1088/1475-7516/2026/02/059","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/059","url":null,"abstract":"The Sunyaev-Zeldovich (SZ) effect is a window into the astrophysical processes of galaxy clusters, and relativistic corrections (the “rSZ”) promise to provide a global census of the gas feedback within clusters. Upcoming wide-field millimeter-wave surveys such as the Simons Observatory (SO), Fred Young Submillimeter Telescope, and CMB-S4 will make increasingly precise measurements of the SZ effect and its relativistic corrections. We present simulated full-sky maps of the rSZ effect and a fast code to generate it, for use in the development of analysis techniques and pipelines. As part of the websky simulation suite, our mock observations have semi-realistic cross-correlations with other large-scale structure tracers, offering insights into the formation and evolution of galaxy clusters and large-scale structure. As a demonstration of this, we examine what an SO-like experiment can learn from the rSZ effect. We find that high significance detections will be possible, provided that the instrumental systematics are under control, and that the evolution of cluster temperatures with mass and redshift can be probed in a manner complementary to X-ray measurements.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"23 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205627","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/062
Aryan Rahimieh, Priyank Parashari, Rui An, Trey Driskell, Jordan Mirocha and Vera Gluscevic
With current and upcoming experiments on the horizon, the global 21-cm signal can open up new avenues for probing dark matter (DM) physics at redshifts that are otherwise inaccessible to other observables. This work investigates the effects of elastic scattering between DM and baryons on the global 21-cm signal in two distinct interacting DM (IDM) models: Coulomb-like and velocity-independent interactions. Our analysis incorporates key astrophysical parameters essential for accurately modeling the global signal, including star formation efficiency, escape fraction of ionizing photons, normalization of the X-ray luminosity, the number of Lyman-Werner photons emitted per stellar baryon, the minimum virial temperature of star-forming halos, as well as the IDM particle mass and cross section. We perform a Fisher analysis to forecast the sensitivity of four global 21-cm signal experimental scenarios as probes of DM-baryon scattering. We find that global signal experiments, even at the sensitivity of the current facilities such as EDGES and SARAS3, could improve existing cosmological and astrophysical constraints on DM-baryon scattering. Our results also highlight the degeneracies among the DM-baryon interaction cross section and astrophysical quantities. In particular, degeneracies between the IDM cross section and two astrophysical parameters, the minimum virial temperature, and Lyman-Werner photon production, can significantly impact the DM interaction inference. Conversely, the velocity-independent cross section is found to be insensitive to uncertainties in the X-ray luminosity. These findings underscore the necessity of accurately characterizing the uncertainties in astrophysical parameters to leverage the full potential of the 21-cm global signal experiments in probing IDM physics.
{"title":"Sensitivity of the global 21-cm signal to dark matter-baryon scattering","authors":"Aryan Rahimieh, Priyank Parashari, Rui An, Trey Driskell, Jordan Mirocha and Vera Gluscevic","doi":"10.1088/1475-7516/2026/02/062","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/062","url":null,"abstract":"With current and upcoming experiments on the horizon, the global 21-cm signal can open up new avenues for probing dark matter (DM) physics at redshifts that are otherwise inaccessible to other observables. This work investigates the effects of elastic scattering between DM and baryons on the global 21-cm signal in two distinct interacting DM (IDM) models: Coulomb-like and velocity-independent interactions. Our analysis incorporates key astrophysical parameters essential for accurately modeling the global signal, including star formation efficiency, escape fraction of ionizing photons, normalization of the X-ray luminosity, the number of Lyman-Werner photons emitted per stellar baryon, the minimum virial temperature of star-forming halos, as well as the IDM particle mass and cross section. We perform a Fisher analysis to forecast the sensitivity of four global 21-cm signal experimental scenarios as probes of DM-baryon scattering. We find that global signal experiments, even at the sensitivity of the current facilities such as EDGES and SARAS3, could improve existing cosmological and astrophysical constraints on DM-baryon scattering. Our results also highlight the degeneracies among the DM-baryon interaction cross section and astrophysical quantities. In particular, degeneracies between the IDM cross section and two astrophysical parameters, the minimum virial temperature, and Lyman-Werner photon production, can significantly impact the DM interaction inference. Conversely, the velocity-independent cross section is found to be insensitive to uncertainties in the X-ray luminosity. These findings underscore the necessity of accurately characterizing the uncertainties in astrophysical parameters to leverage the full potential of the 21-cm global signal experiments in probing IDM physics.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"30 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205629","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/060
Emily Koivu, Nickolay Y. Gnedin and Christopher M. Hirata
Currently the asteroid mass window (mass ∼ 1017- 1021 grams) remains unconstrained for Primordial Black Holes (PBHs) to make up all of the dark matter content of the universe. Given these PBHs have very small masses, their Hawking temperature can be up to hundreds of keV. This study investigates the potential impacts of PBH Hawking radiation on the intergalactic medium from z ∼ 800-25, namely studying the ionization history, kinetic gas temperature, and ultimately the 21 cm signature. We find that for masses on the low edge of the asteroid mass window, there are up two orders of magnitude increases in the ionization fraction and kinetic gas temperature by redshift 25, and the 21 cm spin temperature can differ from non-PBH cosmology by factors of a few. This analysis results in maximum differential brightness temperatures of +17 mK for our lightest PBH masses of 2.12 × 1016g. We also show maximal 53 mK discrepancies in differential brightness temperatures between our PBH and non-PBH cosmologies for our lightest PBH mass, while our heaviest PBH mass of 1.65 × 1017g shows only 0.5 mK variations. We find the Hawking-radiated electrons and positrons are instrumental in driving these IGM modifications. This study shows the necessity for a rigorous treatment of Hawking radiation in PBH cosmological observables from the dark ages through cosmic dawn.
{"title":"Effects of primordial black holes on IGM history","authors":"Emily Koivu, Nickolay Y. Gnedin and Christopher M. Hirata","doi":"10.1088/1475-7516/2026/02/060","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/060","url":null,"abstract":"Currently the asteroid mass window (mass ∼ 1017- 1021 grams) remains unconstrained for Primordial Black Holes (PBHs) to make up all of the dark matter content of the universe. Given these PBHs have very small masses, their Hawking temperature can be up to hundreds of keV. This study investigates the potential impacts of PBH Hawking radiation on the intergalactic medium from z ∼ 800-25, namely studying the ionization history, kinetic gas temperature, and ultimately the 21 cm signature. We find that for masses on the low edge of the asteroid mass window, there are up two orders of magnitude increases in the ionization fraction and kinetic gas temperature by redshift 25, and the 21 cm spin temperature can differ from non-PBH cosmology by factors of a few. This analysis results in maximum differential brightness temperatures of +17 mK for our lightest PBH masses of 2.12 × 1016g. We also show maximal 53 mK discrepancies in differential brightness temperatures between our PBH and non-PBH cosmologies for our lightest PBH mass, while our heaviest PBH mass of 1.65 × 1017g shows only 0.5 mK variations. We find the Hawking-radiated electrons and positrons are instrumental in driving these IGM modifications. This study shows the necessity for a rigorous treatment of Hawking radiation in PBH cosmological observables from the dark ages through cosmic dawn.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"4 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205630","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/064
Tommaso Moretti, Giovanni Verza, Noemi Frusciante and Francesco Pace
Cosmic voids have emerged as powerful probes for cosmology, providing complementary information on the large-scale structure of the universe. We present the first application of a hydrodynamical framework to model the evolution of cosmic voids. This approach offers a physically intuitive characterization of void dynamics and can naturally be applied to non-standard cosmologies. We derive the cosmology-dependent mapping that relates the linear (Lagrangian) and fully non-linear (Eulerian) evolution of the matter density contrast, a central component for accurate theoretical modeling of void statistics. Furthermore, we present a new method for determining the shell-crossing epoch across arbitrary cosmological backgrounds, thereby extending previous treatments restricted to the Einstein-de Sitter universe. Motivated by recent DESI results hinting at dynamical dark energy, we investigate void evolution in w0waCDM cosmologies by varying w0 and wa. We also consider the impact of varying the matter density parameter, Ωm,0. We find that the evolution of isolated, spherically symmetric cosmic voids is most sensitive to Ωm,0 and w0, which can alter the non-linear density contrast by up to 20–30%. Variations in wa have a smaller impact, but may still lead to measurable effects. We also show that the cosmology-dependent mapping between linear and non-linear density contrasts may provide a sensitive probe of dynamical dark energy in precision void analyses.
{"title":"A spherical hydrodynamical model of cosmic voids in ΛCDM and beyond","authors":"Tommaso Moretti, Giovanni Verza, Noemi Frusciante and Francesco Pace","doi":"10.1088/1475-7516/2026/02/064","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/064","url":null,"abstract":"Cosmic voids have emerged as powerful probes for cosmology, providing complementary information on the large-scale structure of the universe. We present the first application of a hydrodynamical framework to model the evolution of cosmic voids. This approach offers a physically intuitive characterization of void dynamics and can naturally be applied to non-standard cosmologies. We derive the cosmology-dependent mapping that relates the linear (Lagrangian) and fully non-linear (Eulerian) evolution of the matter density contrast, a central component for accurate theoretical modeling of void statistics. Furthermore, we present a new method for determining the shell-crossing epoch across arbitrary cosmological backgrounds, thereby extending previous treatments restricted to the Einstein-de Sitter universe. Motivated by recent DESI results hinting at dynamical dark energy, we investigate void evolution in w0waCDM cosmologies by varying w0 and wa. We also consider the impact of varying the matter density parameter, Ωm,0. We find that the evolution of isolated, spherically symmetric cosmic voids is most sensitive to Ωm,0 and w0, which can alter the non-linear density contrast by up to 20–30%. Variations in wa have a smaller impact, but may still lead to measurable effects. We also show that the cosmology-dependent mapping between linear and non-linear density contrasts may provide a sensitive probe of dynamical dark energy in precision void analyses.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"7 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/058
Wen-Mei Li, Jianbo Lu and Shu-Min Wu
We investigate the coherence of mixed Greenberger-Horne-Zeilinger (GHZ) and W states for bosonic and fermionic fields when a subset of n (n < N) qubits experiences Hawking radiation near a Schwarzschild black hole. Analytical expressions are derived for the coherence of mixed N-qubit systems, including both the physically accessible and inaccessible parts in curved spacetime. The results show that the mixed W state maintains its coherence more effectively than the GHZ state as the Hawking temperature increases, even though its entanglement is weaker. As the number of qubits grows, W-state coherence becomes increasingly resistant to gravitational decoherence. Furthermore, fermionic fields preserve stronger entanglement, while bosonic fields retain higher coherence, highlighting a clear contrast between different particle statistics. These findings demonstrate how the Schwarzschild spacetime reshapes the balance between quantum coherence and entanglement, offering guidance for future relativistic quantum information applications.
{"title":"Multiqubit coherence of mixed states near event horizon","authors":"Wen-Mei Li, Jianbo Lu and Shu-Min Wu","doi":"10.1088/1475-7516/2026/02/058","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/058","url":null,"abstract":"We investigate the coherence of mixed Greenberger-Horne-Zeilinger (GHZ) and W states for bosonic and fermionic fields when a subset of n (n < N) qubits experiences Hawking radiation near a Schwarzschild black hole. Analytical expressions are derived for the coherence of mixed N-qubit systems, including both the physically accessible and inaccessible parts in curved spacetime. The results show that the mixed W state maintains its coherence more effectively than the GHZ state as the Hawking temperature increases, even though its entanglement is weaker. As the number of qubits grows, W-state coherence becomes increasingly resistant to gravitational decoherence. Furthermore, fermionic fields preserve stronger entanglement, while bosonic fields retain higher coherence, highlighting a clear contrast between different particle statistics. These findings demonstrate how the Schwarzschild spacetime reshapes the balance between quantum coherence and entanglement, offering guidance for future relativistic quantum information applications.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"52 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205633","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-17DOI: 10.1088/1475-7516/2026/02/057
Wen-Zheng Chen, Yang Liu, Yi-Ming Wang and Hong Li
Delensing — the process of mitigating the lensing-induced B-mode contamination in cosmic microwave background (CMB) observations — will be a pivotal challenge for next-generation CMB experiments seeking to detect primordial gravitational waves (PGWs) through B-mode polarization. This process requires an accurate lensing tracer, which can be obtained either through internal reconstruction from high-resolution CMB observations or from external large-scale structure (LSS) surveys. Ground-based large-aperture telescopes (LATs) are crucial for internal reconstruction, yet existing and planned facilities are confined to the southern hemisphere, limiting effective delensing to that region. In this work, we assess the impact of introducing a northern hemisphere LAT, assumed to be situated near AliCPT (hence termed Ali-like LAT, or LATN), on delensing performance and PGW detection, using simulations. Our baseline setup includes a space-based small-aperture mission (LiteBIRD-like, SAT) and a southern LAT (SO-like, LATS). External LSS tracers, which have been shown to play an important role in delensing before the availability of ultra-sensitive polarization data, are also considered. We find that southern-hemisphere internal delensing reduces the uncertainty in r by ∼17% compared to the no-delensing case. Adding LATN enables full-sky internal delensing, achieving a further ∼18% reduction — comparable to that from including LSS tracers (∼13%). Once LATN is included, the marginal benefit of LSS tracers drops to ∼10%. These results highlight the significant role of LATN in advancing delensing capabilities and improving PGW constraints.
{"title":"From south to north: leveraging ground-based LATs for full-sky CMB delensing and constraints on r","authors":"Wen-Zheng Chen, Yang Liu, Yi-Ming Wang and Hong Li","doi":"10.1088/1475-7516/2026/02/057","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/057","url":null,"abstract":"Delensing — the process of mitigating the lensing-induced B-mode contamination in cosmic microwave background (CMB) observations — will be a pivotal challenge for next-generation CMB experiments seeking to detect primordial gravitational waves (PGWs) through B-mode polarization. This process requires an accurate lensing tracer, which can be obtained either through internal reconstruction from high-resolution CMB observations or from external large-scale structure (LSS) surveys. Ground-based large-aperture telescopes (LATs) are crucial for internal reconstruction, yet existing and planned facilities are confined to the southern hemisphere, limiting effective delensing to that region. In this work, we assess the impact of introducing a northern hemisphere LAT, assumed to be situated near AliCPT (hence termed Ali-like LAT, or LATN), on delensing performance and PGW detection, using simulations. Our baseline setup includes a space-based small-aperture mission (LiteBIRD-like, SAT) and a southern LAT (SO-like, LATS). External LSS tracers, which have been shown to play an important role in delensing before the availability of ultra-sensitive polarization data, are also considered. We find that southern-hemisphere internal delensing reduces the uncertainty in r by ∼17% compared to the no-delensing case. Adding LATN enables full-sky internal delensing, achieving a further ∼18% reduction — comparable to that from including LSS tracers (∼13%). Once LATN is included, the marginal benefit of LSS tracers drops to ∼10%. These results highlight the significant role of LATN in advancing delensing capabilities and improving PGW constraints.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"11 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146205626","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 21-cm signal is a powerful probe of the early Universe's thermal history and could provide a unique avenue for constraining exotic physics. Previous studies have forecasted stringent constraints on energy injections from exotic sources that heat, excite, and ionize the background gas and thereby modify the 21-cm signal. In this work, we quantify the substantial impact that astrophysical uncertainties have on the projected sensitivity to exotic energy injection. In particular, there are significant uncertainties in the minimum star-forming dark matter halo mass, the Lyman-α emission, and the X-ray emission, whose values characterize the fiducial astrophysical model when projecting bounds. As a case study, we investigate the energy injection of accreting primordial black holes of mass ∼ 1 M⊙–103 M⊙, also taking into account uncertainties in the accretion model. We show that, depending on the chosen fiducial model and accretion uncertainties, the sensitivity of future 21-cm data could constrain the abundance of primordial black holes to be either slightly stronger, or significantly weaker, than current limits from the Cosmic Microwave Background.
{"title":"Astrophysical uncertainties challenge 21-cm forecasts: a primordial black hole case study","authors":"Dominic Agius, Rouven Essig, Daniele Gaggero, Sergio Palomares-Ruiz, Gregory Suczewski and Mauro Valli","doi":"10.1088/1475-7516/2026/02/047","DOIUrl":"https://doi.org/10.1088/1475-7516/2026/02/047","url":null,"abstract":"The 21-cm signal is a powerful probe of the early Universe's thermal history and could provide a unique avenue for constraining exotic physics. Previous studies have forecasted stringent constraints on energy injections from exotic sources that heat, excite, and ionize the background gas and thereby modify the 21-cm signal. In this work, we quantify the substantial impact that astrophysical uncertainties have on the projected sensitivity to exotic energy injection. In particular, there are significant uncertainties in the minimum star-forming dark matter halo mass, the Lyman-α emission, and the X-ray emission, whose values characterize the fiducial astrophysical model when projecting bounds. As a case study, we investigate the energy injection of accreting primordial black holes of mass ∼ 1 M⊙–103 M⊙, also taking into account uncertainties in the accretion model. We show that, depending on the chosen fiducial model and accretion uncertainties, the sensitivity of future 21-cm data could constrain the abundance of primordial black holes to be either slightly stronger, or significantly weaker, than current limits from the Cosmic Microwave Background.","PeriodicalId":15445,"journal":{"name":"Journal of Cosmology and Astroparticle Physics","volume":"78 1","pages":""},"PeriodicalIF":6.4,"publicationDate":"2026-02-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146198635","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-02-16DOI: 10.1088/1475-7516/2026/02/052
Ranier Menote and Valerio Marra
Bright sirens, i.e. gravitational-wave detections of compact binary mergers with electromagnetic counterparts, provide a self-calibrated distance-redshift relation and are therefore powerful probes of cosmic expansion. Using the CosmoDC2_BCO catalog, we forecast cosmological constraints from current (LVK) and next-generation (ET, CE) detector networks, in combination with a Roman-like Type Ia supernova sample. We find that third-generation networks reach sub-percent precision on the Hubble constant within a few years, achieving 0.2% after a decade with CE+ET+LVK, while LVK remains limited to the 6% level. The LVK fifth observing run may shed light on the H0 tension only if the inferred value falls outside the range spanned by the Planck and SH0ES determinations, which currently achieve far higher precisions. Supernovae do not directly tighten H0 but stabilize its inference through parameter correlations and enable an absolute calibration of the supernova magnitude MB. In dynamical dark-energy models, the joint analysis of Roman supernovae and bright sirens yields a Figure of Merit of 25 for ET+LVK and 76 for CE+ET+LVK, to be compared with the state-of-the-art DESI DR2 BAO plus DESY5 supernovae value of 56. Sky-localization thresholds of ΔΩ < 50 deg2, or even ΔΩ < 10 deg2, entail only mild penalties, suggesting efficient follow-up strategies. These results establish third-generation GW+EM observations, especially when combined with Roman supernovae, as a cornerstone for precision cosmology in the next decade.
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