Yoo Jung Kim, Michael P. Fitzgerald, Jonathan Lin, Yinzi Xin, Daniel Levinstein, Steph Sallum, Nemanja Jovanovic, Sergio Leon-Saval
We investigate the potential of photonic lantern (PL) fiber fed spectrometers for two-dimensional spectroastrometry. Spectroastrometry, a technique for studying small angular scales by measuring centroid shifts as a function of wavelength, is typically conducted using long-slit spectrographs. However, slit-based spectroastrometry requires observations with multiple position angles to measure two-dimensional spectroastrometric signals. In a typical configuration of PL-fed spectrometers, light from the focal plane is coupled into the few-moded PL, which is then split into several single-mode outputs, with the relative intensities containing astrometric information. The single-moded beams can be fed into a high-resolution spectrometer to measure wavelength-dependent centroid shifts. We perform numerical simulations of a standard 6-port PL and demonstrate its capability of measuring spectroastrometric signals. The effects of photon noise, wavefront errors, and chromaticity are investigated. When the PL is designed to have large linear responses to tip-tilts at the wavelengths of interest, the centroid shifts can be efficiently measured. Furthermore, we provide mock observations of detecting accreting protoplanets. PL spectroastrometry is potentially a simple and efficient technique for detecting spectroastrometric signals.
{"title":"On the Potential of Spectroastrometry with Photonic Lanterns","authors":"Yoo Jung Kim, Michael P. Fitzgerald, Jonathan Lin, Yinzi Xin, Daniel Levinstein, Steph Sallum, Nemanja Jovanovic, Sergio Leon-Saval","doi":"arxiv-2409.09120","DOIUrl":"https://doi.org/arxiv-2409.09120","url":null,"abstract":"We investigate the potential of photonic lantern (PL) fiber fed spectrometers\u0000for two-dimensional spectroastrometry. Spectroastrometry, a technique for\u0000studying small angular scales by measuring centroid shifts as a function of\u0000wavelength, is typically conducted using long-slit spectrographs. However,\u0000slit-based spectroastrometry requires observations with multiple position\u0000angles to measure two-dimensional spectroastrometric signals. In a typical\u0000configuration of PL-fed spectrometers, light from the focal plane is coupled\u0000into the few-moded PL, which is then split into several single-mode outputs,\u0000with the relative intensities containing astrometric information. The\u0000single-moded beams can be fed into a high-resolution spectrometer to measure\u0000wavelength-dependent centroid shifts. We perform numerical simulations of a\u0000standard 6-port PL and demonstrate its capability of measuring\u0000spectroastrometric signals. The effects of photon noise, wavefront errors, and\u0000chromaticity are investigated. When the PL is designed to have large linear\u0000responses to tip-tilts at the wavelengths of interest, the centroid shifts can\u0000be efficiently measured. Furthermore, we provide mock observations of detecting\u0000accreting protoplanets. PL spectroastrometry is potentially a simple and\u0000efficient technique for detecting spectroastrometric signals.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"17 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260644","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}
Joshua Fagin, Eric Paic, Favio Neira, Henry Best, Timo Anguita, Martin Millon, Matthew O'Dowd, Dominique Sluse, Georgios Vernardos
Upcoming wide field surveys such as the Rubin Observatory's Legacy Survey of Space and Time (LSST) will monitor thousands of strongly lensed quasars over a 10-year period. Many of these monitored quasars will undergo high magnification events (HMEs) through microlensing as the accretion disk crosses a caustic, places of infinite magnification. Microlensing allows us to map the inner regions of the accretion disk as it crosses a caustic, even at large cosmological distances. The observational cadences of LSST are not ideal for probing the inner regions of the accretion disk, so there is a need to predict HMEs as early as possible to trigger high-cadence multi-band or spectroscopic follow-up observations. Here we simulate a diverse and realistic sample of 10-year quasar microlensing light curves to train a recurrent neural network (RNN) to predict HMEs before they occur by classifying the location of the peaks at each time step. This is the first deep learning approach to predict HMEs. We give estimates at how well we expect to predict HME peaks during LSST and benchmark how our metrics change with different cadence strategies. With LSST-like observations, we can predict approximately 55% of HME peaks corresponding to tens to hundreds per year and a false positive rate of around 20% compared to the number of HMEs. Our network can be continuously applied throughout the LSST survey, providing crucial alerts to optimize follow-up resources.
{"title":"Predicting High Magnification Events in Microlensed Quasars in the Era of LSST using Recurrent Neural Networks","authors":"Joshua Fagin, Eric Paic, Favio Neira, Henry Best, Timo Anguita, Martin Millon, Matthew O'Dowd, Dominique Sluse, Georgios Vernardos","doi":"arxiv-2409.08999","DOIUrl":"https://doi.org/arxiv-2409.08999","url":null,"abstract":"Upcoming wide field surveys such as the Rubin Observatory's Legacy Survey of\u0000Space and Time (LSST) will monitor thousands of strongly lensed quasars over a\u000010-year period. Many of these monitored quasars will undergo high magnification\u0000events (HMEs) through microlensing as the accretion disk crosses a caustic,\u0000places of infinite magnification. Microlensing allows us to map the inner\u0000regions of the accretion disk as it crosses a caustic, even at large\u0000cosmological distances. The observational cadences of LSST are not ideal for\u0000probing the inner regions of the accretion disk, so there is a need to predict\u0000HMEs as early as possible to trigger high-cadence multi-band or spectroscopic\u0000follow-up observations. Here we simulate a diverse and realistic sample of\u000010-year quasar microlensing light curves to train a recurrent neural network\u0000(RNN) to predict HMEs before they occur by classifying the location of the\u0000peaks at each time step. This is the first deep learning approach to predict\u0000HMEs. We give estimates at how well we expect to predict HME peaks during LSST\u0000and benchmark how our metrics change with different cadence strategies. With\u0000LSST-like observations, we can predict approximately 55% of HME peaks\u0000corresponding to tens to hundreds per year and a false positive rate of around\u000020% compared to the number of HMEs. Our network can be continuously applied\u0000throughout the LSST survey, providing crucial alerts to optimize follow-up\u0000resources.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260653","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}
Anuraag Arya, Harmanjeet Singh Bilkhu, Sandeep Vishwakarma, Hrishikesh Belatikar, Varun Bhalerao, Abhijeet Ghodgaonkar, Jayprakash G. Koyande, Aditi Marathe, N. P. S. Mithun, Sanjoli Narang, Sudhanshu Nimbalkar, Pranav Page, Sourav Palit, Arpit Patel, Amit Shetye, Siddharth Tallur, Shriharsh Tendulkar, Santosh Vadawale, Gaurav Waratkar
Hard X-ray photons with energies in the range of hundreds of keV typically undergo Compton scattering when they are incident on a detector. In this process, an incident photon deposits a fraction of its energy at the point of incidence and continues onward with a change in direction that depends on the amount of energy deposited. By using a pair of detectors to detect the point of incidence and the direction of the scattered photon, we can calculate the scattering direction and angle. The position of a source in the sky can be reconstructed using many Compton photon pairs from a source. We demonstrate this principle in the laboratory by using a pair of Cadmium Zinc Telluride detectors sensitive in the energy range of 20-200 keV. The laboratory setup consists of the two detectors placed perpendicular to each other in a lead-lined box. The detectors are read out by a custom-programmed Xilinx PYNQ FPGA board, and data is then transferred to a PC. The detectors are first calibrated using lines from $^{241}mathrm{Am}$, $^{155}mathrm{Eu}$ and $^{133}mathrm{Ba}$ sources. We irradiated the detectors with a collimated $^{133}mathrm{Ba}$ source and identified Compton scattering events for the 356 keV line. We run a Compton reconstruction algorithm and correctly infer the location of the source in the detector frame. This comprises a successful technology demonstration for a Compton imaging camera in the Hard X-ray regime. We present the details of our setup, the data acquisition process, and software algorithms, and showcase our results.
{"title":"Development of a Compton Imager Setup","authors":"Anuraag Arya, Harmanjeet Singh Bilkhu, Sandeep Vishwakarma, Hrishikesh Belatikar, Varun Bhalerao, Abhijeet Ghodgaonkar, Jayprakash G. Koyande, Aditi Marathe, N. P. S. Mithun, Sanjoli Narang, Sudhanshu Nimbalkar, Pranav Page, Sourav Palit, Arpit Patel, Amit Shetye, Siddharth Tallur, Shriharsh Tendulkar, Santosh Vadawale, Gaurav Waratkar","doi":"arxiv-2409.08822","DOIUrl":"https://doi.org/arxiv-2409.08822","url":null,"abstract":"Hard X-ray photons with energies in the range of hundreds of keV typically\u0000undergo Compton scattering when they are incident on a detector. In this\u0000process, an incident photon deposits a fraction of its energy at the point of\u0000incidence and continues onward with a change in direction that depends on the\u0000amount of energy deposited. By using a pair of detectors to detect the point of\u0000incidence and the direction of the scattered photon, we can calculate the\u0000scattering direction and angle. The position of a source in the sky can be\u0000reconstructed using many Compton photon pairs from a source. We demonstrate\u0000this principle in the laboratory by using a pair of Cadmium Zinc Telluride\u0000detectors sensitive in the energy range of 20-200 keV. The laboratory setup\u0000consists of the two detectors placed perpendicular to each other in a\u0000lead-lined box. The detectors are read out by a custom-programmed Xilinx PYNQ\u0000FPGA board, and data is then transferred to a PC. The detectors are first\u0000calibrated using lines from $^{241}mathrm{Am}$, $^{155}mathrm{Eu}$ and\u0000$^{133}mathrm{Ba}$ sources. We irradiated the detectors with a collimated\u0000$^{133}mathrm{Ba}$ source and identified Compton scattering events for the 356\u0000keV line. We run a Compton reconstruction algorithm and correctly infer the\u0000location of the source in the detector frame. This comprises a successful\u0000technology demonstration for a Compton imaging camera in the Hard X-ray regime.\u0000We present the details of our setup, the data acquisition process, and software\u0000algorithms, and showcase our results.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"29 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260650","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}
Nick TusayDepartment of Astronomy & Astrophysics, The Pennsylvania State UniversityCenter for Exoplanets and Habitable WorldsPenn State Extraterrestrial Intelligence Center, Sofia Z. SheikhPenn State Extraterrestrial Intelligence CenterBreakthrough Listen, University of California, BerkeleySETI Institute, Evan L. SneedDepartment of Earth & Planetary Sciences, University of California, RiversideBreakthrough Listen, University of California, BerkeleyPenn State Extraterrestrial Intelligence Center, Wael FarahBreakthrough Listen, University of California, BerkeleySETI Institute, Alexander W. PollakSETI Institute, Luigi F. CruzSETI Institute, Andrew SiemionBreakthrough Listen, University of California, BerkeleySETI InstituteDepartment of Astronomy, University of California, Berkeley, David R. DeBoerDepartment of Astronomy, University of California, Berkeley, Jason T. WrightDepartment of Astronomy & Astrophysics, The Pennsylvania State UniversityCenter for Exoplanets and Habitable WorldsPenn State Extraterrestrial Intelligence Center
Planet-planet occultations (PPOs) occur when one exoplanet occults another exoplanet in the same system as seen from the Earth's vantage point. PPOs may provide a unique opportunity to observe radio "spillover" from extraterrestrial intelligences' (ETIs) radio transmissions or radar being transmitted from the further exoplanet towards the nearer one for the purposes of communication or scientific exploration. Planetary systems with many tightly packed, low-inclination planets, such as TRAPPIST-1, are predicted to have frequent PPOs. Here, the narrowband technosignature search code turboSETI was used in combination with the newly developed NbeamAnalysis filtering pipeline to analyze 28 hours of beamformed data taken with the Allen Telescope Array (ATA) during late October and early November 2022, from 0.9--9.3~GHz, targeting TRAPPIST-1. During this observing window, 7 possible PPO events were predicted using the NbodyGradient code. The filtering pipeline reduced the original list of 25 million candidate signals down to 6 million by rejecting signals that were not sky-localized and, from these, identified a final list of 11127 candidate signals above a power law cutoff designed to segregate signals by their attenuation and morphological similarity between beams. All signals were plotted for visual inspection, 2264 of which were found to occur during PPO windows. We report no detection of signals of non-human origin, with upper limits calculated for each PPO event exceeding EIRPs of 2.17--13.3 TW for minimally drifting signals and 40.8--421 TW in the maximally drifting case. This work constitutes the longest single-target radio SETI search of TRAPPIST-1 to date.
{"title":"A Radio Technosignature Search of TRAPPIST-1 with the Allen Telescope Array","authors":"Nick TusayDepartment of Astronomy & Astrophysics, The Pennsylvania State UniversityCenter for Exoplanets and Habitable WorldsPenn State Extraterrestrial Intelligence Center, Sofia Z. SheikhPenn State Extraterrestrial Intelligence CenterBreakthrough Listen, University of California, BerkeleySETI Institute, Evan L. SneedDepartment of Earth & Planetary Sciences, University of California, RiversideBreakthrough Listen, University of California, BerkeleyPenn State Extraterrestrial Intelligence Center, Wael FarahBreakthrough Listen, University of California, BerkeleySETI Institute, Alexander W. PollakSETI Institute, Luigi F. CruzSETI Institute, Andrew SiemionBreakthrough Listen, University of California, BerkeleySETI InstituteDepartment of Astronomy, University of California, Berkeley, David R. DeBoerDepartment of Astronomy, University of California, Berkeley, Jason T. WrightDepartment of Astronomy & Astrophysics, The Pennsylvania State UniversityCenter for Exoplanets and Habitable WorldsPenn State Extraterrestrial Intelligence Center","doi":"arxiv-2409.08313","DOIUrl":"https://doi.org/arxiv-2409.08313","url":null,"abstract":"Planet-planet occultations (PPOs) occur when one exoplanet occults another\u0000exoplanet in the same system as seen from the Earth's vantage point. PPOs may\u0000provide a unique opportunity to observe radio \"spillover\" from extraterrestrial\u0000intelligences' (ETIs) radio transmissions or radar being transmitted from the\u0000further exoplanet towards the nearer one for the purposes of communication or\u0000scientific exploration. Planetary systems with many tightly packed,\u0000low-inclination planets, such as TRAPPIST-1, are predicted to have frequent\u0000PPOs. Here, the narrowband technosignature search code turboSETI was used in\u0000combination with the newly developed NbeamAnalysis filtering pipeline to\u0000analyze 28 hours of beamformed data taken with the Allen Telescope Array (ATA)\u0000during late October and early November 2022, from 0.9--9.3~GHz, targeting\u0000TRAPPIST-1. During this observing window, 7 possible PPO events were predicted\u0000using the NbodyGradient code. The filtering pipeline reduced the original list\u0000of 25 million candidate signals down to 6 million by rejecting signals that\u0000were not sky-localized and, from these, identified a final list of 11127\u0000candidate signals above a power law cutoff designed to segregate signals by\u0000their attenuation and morphological similarity between beams. All signals were\u0000plotted for visual inspection, 2264 of which were found to occur during PPO\u0000windows. We report no detection of signals of non-human origin, with upper\u0000limits calculated for each PPO event exceeding EIRPs of 2.17--13.3 TW for\u0000minimally drifting signals and 40.8--421 TW in the maximally drifting case.\u0000This work constitutes the longest single-target radio SETI search of TRAPPIST-1\u0000to date.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260655","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}
Senkhosi Simelane, Roger Deane, Athol Kemball, Roelf Botha, Roufurd Julie, Keitumetse Molamu, Adrian Tiplady, Aletha de Witt
Global expansion of the Event Horizon Telescope (EHT) will see the strategic addition of antennas at new geographical locations, transforming the sensitivity and imaging fidelity of the $lambda sim 1,$mm EHT array. A possible South African EHT station would leverage a strong geographical advantage, local infrastructure, and radio astronomy expertise, and have strong synergies with the Africa Millimetre Telescope in Namibia. We assessed three South African candidate millimetre sites using climatological simulations and found at least two promising sites. These sites are comparable to some existing EHT stations during the typical April EHT observing window and outperform them during most of the year, especially the southern hemisphere winter. Interferometric simulations of Africa-enhanced EHT arrays under the simulated atmospheric conditions demonstrate the improved array performance. In typical weather, the number of reliable visibility detections increased considerably, especially at $(u, v)$-distances corresponding to the angular sizes of the Sagittarius A$^*$ and Messier 87$^*$ black hole shadow diameters ($sim40,mathrm{mu}$as to $50,mathrm{mu}$as). The simulation results underscore the sizable, positive impact of a strategically placed South African EHT station on ngEHT objectives and the resulting black hole science.
{"title":"Evaluation of South African Candidate Sites for an Expanded Event Horizon Telescope","authors":"Senkhosi Simelane, Roger Deane, Athol Kemball, Roelf Botha, Roufurd Julie, Keitumetse Molamu, Adrian Tiplady, Aletha de Witt","doi":"arxiv-2409.08003","DOIUrl":"https://doi.org/arxiv-2409.08003","url":null,"abstract":"Global expansion of the Event Horizon Telescope (EHT) will see the strategic\u0000addition of antennas at new geographical locations, transforming the\u0000sensitivity and imaging fidelity of the $lambda sim 1,$mm EHT array. A\u0000possible South African EHT station would leverage a strong geographical\u0000advantage, local infrastructure, and radio astronomy expertise, and have strong\u0000synergies with the Africa Millimetre Telescope in Namibia. We assessed three\u0000South African candidate millimetre sites using climatological simulations and\u0000found at least two promising sites. These sites are comparable to some existing\u0000EHT stations during the typical April EHT observing window and outperform them\u0000during most of the year, especially the southern hemisphere winter.\u0000Interferometric simulations of Africa-enhanced EHT arrays under the simulated\u0000atmospheric conditions demonstrate the improved array performance. In typical\u0000weather, the number of reliable visibility detections increased considerably,\u0000especially at $(u, v)$-distances corresponding to the angular sizes of the\u0000Sagittarius A$^*$ and Messier 87$^*$ black hole shadow diameters\u0000($sim40,mathrm{mu}$as to $50,mathrm{mu}$as). The simulation results\u0000underscore the sizable, positive impact of a strategically placed South African\u0000EHT station on ngEHT objectives and the resulting black hole science.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"7 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217310","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}
N. Blind, M. Shinde, I. Dinis, N. Restori, B. Chazelas, T. Fusco, O. Guyon, J. Kuehn, C. Lovis, P. Martinez, M. Motte, J. -F. Sauvage, A. Spang
RISTRETTO is the evolution of the original idea of coupling the VLT instruments SPHERE and ESPRESSO cite{lovis_2016a}, aiming at High Dispersion Coronagraphy. RISTRETTO is a visitor instrument that should enable the characterization of the atmospheres of nearby exoplanets in reflected light, by using the technique of high-contrast, high-resolution spectroscopy. Its goal is to observe Prox Cen b and other planets placed at about 35mas from their star, i.e. $2lambda/D$ at $lambda$=750nm. The instrument is composed of an extreme adaptive optics, a coronagraphic Integral Field Unit, and a diffraction-limited spectrograph (R=140.000, $lambda =$620-840 nm). We present the RISTRETTO XAO architecture that reach the specification, providing contrasts down to $5times10^{-5}$ at 2$lambda/D$ from the star in the visible, in the presence of atmosphere and low wind effect. This performance is allowed by a new two-sensors-one-dm architecture, some variations to the already known concepts of unmodulated pyWFS and zWFS, and exploiting to the maximum of their capabilities the state-of-the-art high speed, low noise cameras & fast DM. We present the result of end-to-end simulations, that demonstrate stable closed loop operation of an unmodulated pyramid and a zernike WFS (together), and in presence of low wind effect.
{"title":"RISTRETTO: a VLT XAO design to reach Proxima Cen b in the visible","authors":"N. Blind, M. Shinde, I. Dinis, N. Restori, B. Chazelas, T. Fusco, O. Guyon, J. Kuehn, C. Lovis, P. Martinez, M. Motte, J. -F. Sauvage, A. Spang","doi":"arxiv-2409.08052","DOIUrl":"https://doi.org/arxiv-2409.08052","url":null,"abstract":"RISTRETTO is the evolution of the original idea of coupling the VLT\u0000instruments SPHERE and ESPRESSO cite{lovis_2016a}, aiming at High Dispersion\u0000Coronagraphy. RISTRETTO is a visitor instrument that should enable the\u0000characterization of the atmospheres of nearby exoplanets in reflected light, by\u0000using the technique of high-contrast, high-resolution spectroscopy. Its goal is\u0000to observe Prox Cen b and other planets placed at about 35mas from their star,\u0000i.e. $2lambda/D$ at $lambda$=750nm. The instrument is composed of an extreme\u0000adaptive optics, a coronagraphic Integral Field Unit, and a diffraction-limited\u0000spectrograph (R=140.000, $lambda =$620-840 nm). We present the RISTRETTO XAO architecture that reach the specification,\u0000providing contrasts down to $5times10^{-5}$ at 2$lambda/D$ from the star in\u0000the visible, in the presence of atmosphere and low wind effect. This\u0000performance is allowed by a new two-sensors-one-dm architecture, some\u0000variations to the already known concepts of unmodulated pyWFS and zWFS, and\u0000exploiting to the maximum of their capabilities the state-of-the-art high\u0000speed, low noise cameras & fast DM. We present the result of end-to-end\u0000simulations, that demonstrate stable closed loop operation of an unmodulated\u0000pyramid and a zernike WFS (together), and in presence of low wind effect.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"3 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217309","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}
The prospect of phased laser arrays in space has received considerable attention in recent years, with applications to both planetary defence and space exploration. The most detailed investigation conducted into such a design is that of the DE-STAR phased array, standing for $textbf{D}$irected $textbf{E}$nergy $textbf{S}$ystems for $textbf{T}$argeting of $textbf{A}$steroids and explo$textbf{R}$ation. DE-STAR is a square modular design which exploits the energy created by banks of solar cells in space to generate and amplify the power of a laser beam. A specific DE-STAR design is expressed as DE-STAR n, where 'n' (typically in the range 0 - 4) equates to the log to base 10 of the side, in metres, of a square bank of lasers. With a DE-STAR 4 structure (10 km $times$ 10 km square) capable of generating a laser beam on the order of tens of gigawatts, clearly there is the potential for such an asset to be deployed as a weapon by targeting locations on Earth. This naturally leads to the question of what effective ways can this possible misuse be removed or at least mitigated, to ensure these powerful space lasers can only be used for their intended purpose, and never malevolent reasons. One solution would be to locate the DE-STAR far enough away so that the laser flux at Earth would be too low. Results indicate that given they should lie 1 au from the Sun, there are feasible locations for DE-STAR 0-2 arrays where there is no danger to Earth. For DE-STAR 4-5, such is their power, safety measures other than those considered here would have to be adopted. Positions in the Solar System where the DE-STAR lasers have no direct line-of-sight with Earth tend to be unstable, and would require regular corrections using an on-board propulsion system, or preferably using push-back from the laser itself.
{"title":"Minimum Safe Distances for DE-STAR Space Lasers","authors":"Adam Hibberd","doi":"arxiv-2409.08873","DOIUrl":"https://doi.org/arxiv-2409.08873","url":null,"abstract":"The prospect of phased laser arrays in space has received considerable\u0000attention in recent years, with applications to both planetary defence and\u0000space exploration. The most detailed investigation conducted into such a design\u0000is that of the DE-STAR phased array, standing for $textbf{D}$irected\u0000$textbf{E}$nergy $textbf{S}$ystems for $textbf{T}$argeting of\u0000$textbf{A}$steroids and explo$textbf{R}$ation. DE-STAR is a square modular\u0000design which exploits the energy created by banks of solar cells in space to\u0000generate and amplify the power of a laser beam. A specific DE-STAR design is\u0000expressed as DE-STAR n, where 'n' (typically in the range 0 - 4) equates to the\u0000log to base 10 of the side, in metres, of a square bank of lasers. With a\u0000DE-STAR 4 structure (10 km $times$ 10 km square) capable of generating a laser\u0000beam on the order of tens of gigawatts, clearly there is the potential for such\u0000an asset to be deployed as a weapon by targeting locations on Earth. This\u0000naturally leads to the question of what effective ways can this possible misuse\u0000be removed or at least mitigated, to ensure these powerful space lasers can\u0000only be used for their intended purpose, and never malevolent reasons. One\u0000solution would be to locate the DE-STAR far enough away so that the laser flux\u0000at Earth would be too low. Results indicate that given they should lie 1 au\u0000from the Sun, there are feasible locations for DE-STAR 0-2 arrays where there\u0000is no danger to Earth. For DE-STAR 4-5, such is their power, safety measures\u0000other than those considered here would have to be adopted. Positions in the\u0000Solar System where the DE-STAR lasers have no direct line-of-sight with Earth\u0000tend to be unstable, and would require regular corrections using an on-board\u0000propulsion system, or preferably using push-back from the laser itself.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"26 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260698","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}
Joseph Farah, Peter Galison, Kazunori Akiyama, Katherine L. Bouman, Geoffrey C. Bower, Andrew Chael, Antonio Fuentes, José L. Gómez, Mareki Honma, Michael D. Johnson, Yutaro Kofuji, Daniel P. Marrone, Kotaro Moriyama, Ramesh Narayan, Dominic W. Pesce, Paul Tiede, Maciek Wielgus, Guang-Yao Zhao, The Event Horizon Telescope Collaboration
Recent developments in very long baseline interferometry (VLBI) have made it possible for the Event Horizon Telescope (EHT) to resolve the innermost accretion flows of the largest supermassive black holes on the sky. The sparse nature of the EHT's $(u, v)$-coverage presents a challenge when attempting to resolve highly time-variable sources. We demonstrate that the changing (u, v)-coverage of the EHT can contain regions of time over the course of a single observation that facilitate dynamical imaging. These optimal time regions typically have projected baseline distributions that are approximately angularly isotropic and radially homogeneous. We derive a metric of coverage quality based on baseline isotropy and density that is capable of ranking array configurations by their ability to produce accurate dynamical reconstructions. We compare this metric to existing metrics in the literature and investigate their utility by performing dynamical reconstructions on synthetic data from simulated EHT observations of sources with simple orbital variability. We then use these results to make recommendations for imaging the 2017 EHT Sgr A* data set.
{"title":"Selective Dynamical Imaging of Interferometric Data","authors":"Joseph Farah, Peter Galison, Kazunori Akiyama, Katherine L. Bouman, Geoffrey C. Bower, Andrew Chael, Antonio Fuentes, José L. Gómez, Mareki Honma, Michael D. Johnson, Yutaro Kofuji, Daniel P. Marrone, Kotaro Moriyama, Ramesh Narayan, Dominic W. Pesce, Paul Tiede, Maciek Wielgus, Guang-Yao Zhao, The Event Horizon Telescope Collaboration","doi":"arxiv-2409.08321","DOIUrl":"https://doi.org/arxiv-2409.08321","url":null,"abstract":"Recent developments in very long baseline interferometry (VLBI) have made it\u0000possible for the Event Horizon Telescope (EHT) to resolve the innermost\u0000accretion flows of the largest supermassive black holes on the sky. The sparse\u0000nature of the EHT's $(u, v)$-coverage presents a challenge when attempting to\u0000resolve highly time-variable sources. We demonstrate that the changing (u,\u0000v)-coverage of the EHT can contain regions of time over the course of a single\u0000observation that facilitate dynamical imaging. These optimal time regions\u0000typically have projected baseline distributions that are approximately\u0000angularly isotropic and radially homogeneous. We derive a metric of coverage\u0000quality based on baseline isotropy and density that is capable of ranking array\u0000configurations by their ability to produce accurate dynamical reconstructions.\u0000We compare this metric to existing metrics in the literature and investigate\u0000their utility by performing dynamical reconstructions on synthetic data from\u0000simulated EHT observations of sources with simple orbital variability. We then\u0000use these results to make recommendations for imaging the 2017 EHT Sgr A* data\u0000set.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"47 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142260652","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}
Jennifer B. Bergner, J. A. Sturm, Elettra L. Piacentino, M. K. McClure, Karin I. Oberg, A. C. A. Boogert, E. Dartois, M. N. Drozdovskaya, H. J. Fraser, Daniel Harsono, Sergio Ioppolo, Charles J. Law, Dariusz C. Lis, Brett A. McGuire, Gary J. Melnick, Jennifer A. Noble, M. E. Palumbo, Yvonne J. Pendleton, Giulia Perotti, Danna Qasim, W. R. M. Rocha, E. F. van Dishoeck
Planet formation is strongly influenced by the composition and distribution of volatiles within protoplanetary disks. With JWST, it is now possible to obtain direct observational constraints on disk ices, as recently demonstrated by the detection of ice absorption features towards the edge-on HH 48 NE disk as part of the Ice Age Early Release Science program. Here, we introduce a new radiative transfer modeling framework designed to retrieve the composition and mixing status of disk ices using their band profiles, and apply it to interpret the H2O, CO2, and CO ice bands observed towards the HH 48 NE disk. We show that the ices are largely present as mixtures, with strong evidence for CO trapping in both H2O and CO2 ice. The HH 48 NE disk ice composition (pure vs. polar vs. apolar fractions) is markedly different from earlier protostellar stages, implying thermal and/or chemical reprocessing during the formation or evolution of the disk. We infer low ice-phase C/O ratios around 0.1 throughout the disk, and also demonstrate that the mixing and entrapment of disk ices can dramatically affect the radial dependence of the C/O ratio. It is therefore imperative that realistic disk ice compositions are considered when comparing planetary compositions with potential formation scenarios, which will fortunately be possible for an increasing number of disks with JWST.
行星的形成受到原行星盘内挥发物成分和分布的强烈影响。利用 JWST，现在有可能获得对磁盘冰的直接观测约束，最近在冰河时代早期释放科学计划中探测到的 HH 48 NE 磁盘边缘冰吸收特征就证明了这一点。在这里，我们引入了一个新的辐射传递建模框架，旨在利用其带轮廓来检索磁盘冰的成分和混合状态，并将其应用于解释在HH 48 NE磁盘上观测到的H2O、CO2和CO冰带。我们的研究表明，这些冰在很大程度上是以混合物的形式存在的，有强有力的证据表明 H2O 和 CO2 冰中都有 CO 包裹。HH 48 NE圆盘冰的成分（纯冰与极冰与极冰部分）与早期原恒星阶段明显不同，这意味着圆盘在形成或演化过程中进行了热和/或化学再处理。我们推断整个星盘的冰相C/O比值较低，约为0.1，同时还证明了星盘冰的混合和夹带会极大地影响C/O比值的径向依赖性。因此，在比较行星成分与潜在的形成情况时，考虑现实的盘冰成分是非常重要的，幸运的是，这将有可能通过 JWST 对越来越多的盘进行研究。
{"title":"JWST ice band profiles reveal mixed ice compositions in the HH 48 NE disk","authors":"Jennifer B. Bergner, J. A. Sturm, Elettra L. Piacentino, M. K. McClure, Karin I. Oberg, A. C. A. Boogert, E. Dartois, M. N. Drozdovskaya, H. J. Fraser, Daniel Harsono, Sergio Ioppolo, Charles J. Law, Dariusz C. Lis, Brett A. McGuire, Gary J. Melnick, Jennifer A. Noble, M. E. Palumbo, Yvonne J. Pendleton, Giulia Perotti, Danna Qasim, W. R. M. Rocha, E. F. van Dishoeck","doi":"arxiv-2409.08117","DOIUrl":"https://doi.org/arxiv-2409.08117","url":null,"abstract":"Planet formation is strongly influenced by the composition and distribution\u0000of volatiles within protoplanetary disks. With JWST, it is now possible to\u0000obtain direct observational constraints on disk ices, as recently demonstrated\u0000by the detection of ice absorption features towards the edge-on HH 48 NE disk\u0000as part of the Ice Age Early Release Science program. Here, we introduce a new\u0000radiative transfer modeling framework designed to retrieve the composition and\u0000mixing status of disk ices using their band profiles, and apply it to interpret\u0000the H2O, CO2, and CO ice bands observed towards the HH 48 NE disk. We show that\u0000the ices are largely present as mixtures, with strong evidence for CO trapping\u0000in both H2O and CO2 ice. The HH 48 NE disk ice composition (pure vs. polar vs.\u0000apolar fractions) is markedly different from earlier protostellar stages,\u0000implying thermal and/or chemical reprocessing during the formation or evolution\u0000of the disk. We infer low ice-phase C/O ratios around 0.1 throughout the disk,\u0000and also demonstrate that the mixing and entrapment of disk ices can\u0000dramatically affect the radial dependence of the C/O ratio. It is therefore\u0000imperative that realistic disk ice compositions are considered when comparing\u0000planetary compositions with potential formation scenarios, which will\u0000fortunately be possible for an increasing number of disks with JWST.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"9 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217311","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}
Lehman H. Garrison, Dan Foreman-Mackey, Yu-hsuan Shih, Alex Barnett
We present nifty-ls, a software package for fast and accurate evaluation of the Lomb-Scargle periodogram. nifty-ls leverages the fact that Lomb-Scargle can be computed using a non-uniform FFT (NUFFT), which we evaluate with the Flatiron Institute NUFFT package (finufft). This approach achieves a many-fold speedup over the Press & Rybicki (1989) method as implemented in Astropy and is simultaneously many orders of magnitude more accurate. nifty-ls also supports fast evaluation on GPUs via CUDA and integrates with the Astropy Lomb-Scargle interface. nifty-ls is publicly available as open-source software.
{"title":"nifty-ls: Fast and Accurate Lomb-Scargle Periodograms Using a Non-Uniform FFT","authors":"Lehman H. Garrison, Dan Foreman-Mackey, Yu-hsuan Shih, Alex Barnett","doi":"arxiv-2409.08090","DOIUrl":"https://doi.org/arxiv-2409.08090","url":null,"abstract":"We present nifty-ls, a software package for fast and accurate evaluation of\u0000the Lomb-Scargle periodogram. nifty-ls leverages the fact that Lomb-Scargle can\u0000be computed using a non-uniform FFT (NUFFT), which we evaluate with the\u0000Flatiron Institute NUFFT package (finufft). This approach achieves a many-fold\u0000speedup over the Press & Rybicki (1989) method as implemented in Astropy and is\u0000simultaneously many orders of magnitude more accurate. nifty-ls also supports\u0000fast evaluation on GPUs via CUDA and integrates with the Astropy Lomb-Scargle\u0000interface. nifty-ls is publicly available as open-source software.","PeriodicalId":501163,"journal":{"name":"arXiv - PHYS - Instrumentation and Methods for Astrophysics","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2024-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142217308","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}
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