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arXiv:2502.18651v2 Announce Type: replace Abstract: In this second paper on the variability survey of central stars of planetary nebulae (CSPNe) using ZTF, we focus on the 11 long-timescale variables with variability timescales ranging from months to years. We also present preliminary analyses based on spectroscopic and/or photometric follow-up observations for six of them. Among them is NGC 6833, which shows a 980 day periodic variability with strange characteristics: 'triangle-shaped' brightening in $r$, $i$, and WISE bands but almost coincidental shallow dips in the $g$-band. We speculate this to be a wide but eccentric binary with the same orbital period. Long-period near-sinusoidal variability was detected in two other systems, NGC 6905 and Kn 26, with periods of 700 days and 230 days, respectively, making them additional wide-binary candidates. The latter also shows a short period at 1.18 hours which can either be from a close inner binary or pulsational origin. We present CTSS 2 and PN K 3-5 which show brightening and significant reddening over the whole ZTF baseline. A stellar model fit to the optical spectrum of CTSS 2 reveals it to be one of the youngest post-AGB CSPN known. Both show high-density emission-line cores. These appear to be late thermal pulse candidates, currently evolving towards the AGB phase, though alternative explanations are possible. We then present recent HST/COS ultraviolet spectroscopy of the known wide-binary candidate LoTr 1 showing that the hot star is a spectroscopic twin of the extremely hot white dwarf in UCAC2 46706450. We think that the long photometric period of 11 years is the binary orbital period. Finally, we briefly discuss the ZTF light curves of the remaining variables, namely Tan 2, K 3-20, WHTZ 3, Kn J1857+3931, and IPHAS J1927+0814. With these examples, we present the effectiveness of the von Neumann statistics and Pearson Skew-based metric space in searching for long-timescale variables.

arXiv:2502.18651v2 Announce Type: replace Abstract: In this second paper on the variability survey of central stars of planetary nebulae (CSPNe) using ZTF, we focus on the 11 long-timescale variables with variability timescales ranging from months to years. We also present preliminary analyses based on spectroscopic and/or photometric follow-up observations for six of them. Among them is NGC 6833, which shows a 980 day periodic variability with strange characteristics: 'triangle-shaped' brightening in $r$, $i$, and WISE bands but almost coincidental shallow dips in the $g$-band. We speculate this to be a wide but eccentric binary with the same orbital period. Long-period near-sinusoidal variability was detected in two other systems, NGC 6905 and Kn 26, with periods of 700 days and 230 days, respectively, making them additional wide-binary candidates. The latter also shows a short period at 1.18 hours which can either be from a close inner binary or pulsational origin. We present CTSS 2 and PN K 3-5 which show brightening and significant reddening over the whole ZTF baseline. A stellar model fit to the optical spectrum of CTSS 2 reveals it to be one of the youngest post-AGB CSPN known. Both show high-density emission-line cores. These appear to be late thermal pulse candidates, currently evolving towards the AGB phase, though alternative explanations are possible. We then present recent HST/COS ultraviolet spectroscopy of the known wide-binary candidate LoTr 1 showing that the hot star is a spectroscopic twin of the extremely hot white dwarf in UCAC2 46706450. We think that the long photometric period of 11 years is the binary orbital period. Finally, we briefly discuss the ZTF light curves of the remaining variables, namely Tan 2, K 3-20, WHTZ 3, Kn J1857+3931, and IPHAS J1927+0814. With these examples, we present the effectiveness of the von Neumann statistics and Pearson Skew-based metric space in searching for long-timescale variables.

arXiv:2404.16261v3 Announce Type: replace Abstract: Over twenty years ago, Type Ia Supernovae (SNIa) observations revealed an accelerating Universe expansion, suggesting a significant dark energy presence, often modelled as a cosmological constant, \( \Lambda \). Despite its pivotal role in cosmology, the standard $\Lambda$CDM model remains largely underexplored in the redshift range between distant SNIa and the Cosmic Microwave Background (CMB). This study harnesses the James Webb Space Telescope's advanced capabilities to extend the Hubble flow mapping across an unprecedented redshift range, from \( z \approx 0 \) to \( z \approx 7.5 \). Using a dataset of 231 HII galaxies and extragalactic HII regions, we employ the \(\text{L}-\sigma\) relation that correlates the luminosity of Balmer lines with their velocity dispersion, to define a competitive technique for measuring cosmic distances. This approach allows the mapping of the Universe expansion history over more than 12 billion years, covering 95\% of its age. Our analysis, using Bayesian inference, constrains the parameter space $\lbrace h, \Omega_m, w_0\rbrace = \lbrace 0.731\pm0.039, 0.302^{+0.12}_{-0.069}, -1.01^{+0.52}_{-0.29}\rbrace $ (statistical) for a flat Universe. Our results provide new insights into cosmic evolution and imply a lack of change in the photo-kinematical properties of the young massive ionizing clusters in HII galaxies across most of the history of the Universe.

arXiv:2404.16261v3 Announce Type: replace Abstract: Over twenty years ago, Type Ia Supernovae (SNIa) observations revealed an accelerating Universe expansion, suggesting a significant dark energy presence, often modelled as a cosmological constant, \( \Lambda \). Despite its pivotal role in cosmology, the standard $\Lambda$CDM model remains largely underexplored in the redshift range between distant SNIa and the Cosmic Microwave Background (CMB). This study harnesses the James Webb Space Telescope's advanced capabilities to extend the Hubble flow mapping across an unprecedented redshift range, from \( z \approx 0 \) to \( z \approx 7.5 \). Using a dataset of 231 HII galaxies and extragalactic HII regions, we employ the \(\text{L}-\sigma\) relation that correlates the luminosity of Balmer lines with their velocity dispersion, to define a competitive technique for measuring cosmic distances. This approach allows the mapping of the Universe expansion history over more than 12 billion years, covering 95\% of its age. Our analysis, using Bayesian inference, constrains the parameter space $\lbrace h, \Omega_m, w_0\rbrace = \lbrace 0.731\pm0.039, 0.302^{+0.12}_{-0.069}, -1.01^{+0.52}_{-0.29}\rbrace $ (statistical) for a flat Universe. Our results provide new insights into cosmic evolution and imply a lack of change in the photo-kinematical properties of the young massive ionizing clusters in HII galaxies across most of the history of the Universe.

arXiv:2503.00636v1 Announce Type: new Abstract: We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply most of the observatory's power. The LAT survey will cover about 60% of the sky at a regular observing cadence, with five times the angular resolution and ten times the map depth of Planck. The science goals are to: (1) determine the physical conditions in the early universe and constrain the existence of new light particles; (2) measure the integrated distribution of mass, electron pressure, and electron momentum in the late-time universe, and, in combination with optical surveys, determine the neutrino mass and the effects of dark energy via tomographic measurements of the growth of structure at $z < 3$; (3) measure the distribution of electron density and pressure around galaxy groups and clusters, and calibrate the effects of energy input from galaxy formation on the surrounding environment; (4) produce a sample of more than 30,000 galaxy clusters, and more than 100,000 extragalactic millimeter sources, including regularly sampled AGN light-curves, to study these sources and their emission physics; (5) measure the polarized emission from magnetically aligned dust grains in our Galaxy, to study the properties of dust and the role of magnetic fields in star formation; (6) constrain asteroid regoliths, search for Trans-Neptunian Objects, and either detect or eliminate large portions of the phase space in the search for Planet 9; and (7) provide a powerful new window into the transient universe on time scales of minutes to years, concurrent with observations from Rubin of overlapping sky.

arXiv:2503.00636v1 Announce Type: new Abstract: We describe updated scientific goals for the wide-field, millimeter-wave survey that will be produced by the Simons Observatory (SO). Significant upgrades to the 6-meter SO Large Aperture Telescope (LAT) are expected to be complete by 2028, and will include a doubled mapping speed with 30,000 new detectors and an automated data reduction pipeline. In addition, a new photovoltaic array will supply most of the observatory's power. The LAT survey will cover about 60% of the sky at a regular observing cadence, with five times the angular resolution and ten times the map depth of Planck. The science goals are to: (1) determine the physical conditions in the early universe and constrain the existence of new light particles; (2) measure the integrated distribution of mass, electron pressure, and electron momentum in the late-time universe, and, in combination with optical surveys, determine the neutrino mass and the effects of dark energy via tomographic measurements of the growth of structure at $z < 3$; (3) measure the distribution of electron density and pressure around galaxy groups and clusters, and calibrate the effects of energy input from galaxy formation on the surrounding environment; (4) produce a sample of more than 30,000 galaxy clusters, and more than 100,000 extragalactic millimeter sources, including regularly sampled AGN light-curves, to study these sources and their emission physics; (5) measure the polarized emission from magnetically aligned dust grains in our Galaxy, to study the properties of dust and the role of magnetic fields in star formation; (6) constrain asteroid regoliths, search for Trans-Neptunian Objects, and either detect or eliminate large portions of the phase space in the search for Planet 9; and (7) provide a powerful new window into the transient universe on time scales of minutes to years, concurrent with observations from Rubin of overlapping sky.

arXiv:2503.00113v1 Announce Type: new Abstract: The integral-field unit mode of the Near-Infrared Spectrograph (NIRSpec+IFU) mounted on the James Webb Space Telescope has now enabled kinematic studies of smaller and less massive compact stellar systems in which to search for central massive black holes (BHs) than ever before. We present here the first such detection using NIRSpec+IFU in its highest resolution (R~2700) mode. We report a $3\sigma$ detection of a central black hole with mass ${\cal M}_{BH}=2.2\pm1.1\times10^6\,M_\odot$ in UCD736 orbiting within the Virgo galaxy cluster based on Schwarzschild's modeling of the 1D kinematic profile. The presence of such a massive BH strongly argues against a globular cluster origin of this UCD, and rather suggests a tidally stripped formation route from a former $\gtrsim10^9\,M_\odot$ dwarf galaxy host. Two other methods produce results consistent with Schwarzschild's modelling, but can only provide upper-limits on ${\cal M}_{BH}$. This represents the detection of a BH in the most compact ($r_h\approx15\,{\rm pc}$) stellar system to date, with a ${\cal M}_{BH}$ corresponding to ~9 percent of the system's stellar mass, roughly in line with previously reported UCD BH detections and comparable to the BH detected in the compact elliptical galaxy NGC4486B.

arXiv:2503.00113v1 Announce Type: new Abstract: The integral-field unit mode of the Near-Infrared Spectrograph (NIRSpec+IFU) mounted on the James Webb Space Telescope has now enabled kinematic studies of smaller and less massive compact stellar systems in which to search for central massive black holes (BHs) than ever before. We present here the first such detection using NIRSpec+IFU in its highest resolution (R~2700) mode. We report a $3\sigma$ detection of a central black hole with mass ${\cal M}_{BH}=2.2\pm1.1\times10^6\,M_\odot$ in UCD736 orbiting within the Virgo galaxy cluster based on Schwarzschild's modeling of the 1D kinematic profile. The presence of such a massive BH strongly argues against a globular cluster origin of this UCD, and rather suggests a tidally stripped formation route from a former $\gtrsim10^9\,M_\odot$ dwarf galaxy host. Two other methods produce results consistent with Schwarzschild's modelling, but can only provide upper-limits on ${\cal M}_{BH}$. This represents the detection of a BH in the most compact ($r_h\approx15\,{\rm pc}$) stellar system to date, with a ${\cal M}_{BH}$ corresponding to ~9 percent of the system's stellar mass, roughly in line with previously reported UCD BH detections and comparable to the BH detected in the compact elliptical galaxy NGC4486B.

The best chance to see as many as possible will be after sunset on Wednesday and Thursday.

Nature, Published online: 03 March 2025; doi:10.1038/d41586-025-00670-7

The touchdown is a much-needed win for NASA’s partnerships with commercial space companies.

The second-ever commercial landing on the moon comes amid a flurry of lunar exploration activity that will see around a dozen missions this year alone

2025 Scott Lectures - Lecture 1 New field of quantum science and engineering

Abstract not available

Drinks and nibbles will be served after the lecture

• Speaker: Professor Mikhail Lukin, Harvard University
• Monday 03 March 2025, 16:00-17:00
• Venue: Ray Dolby Auditorium, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
• Series: Scott Lectures; organiser: Leona Hope-Coles.

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2025 Scott Lectures - Exploring quantum computing frontier with programmable atom arrays

Abstract not available

Refreshments will be served after the lecture

• Speaker: Professor Mikhail Lukin, Harvard University
• Wednesday 05 March 2025, 16:00-17:00
• Venue: Ray Dolby Auditorium, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
• Series: Scott Lectures; organiser: Leona Hope-Coles.

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2025 Scott Lectures - Quantum science with atom-like systems in diamond

Abstract not available

• Speaker: Professor Mikhail Lukin, Harvard University
• Thursday 06 March 2025, 11:00-12:00
• Venue: Cluster Seminar Room, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
• Series: Scott Lectures; organiser: Leona Hope-Coles.

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A phase transition in cosmological fluid dynamics

On a background Minkowski spacetime, the Euler equations (both relativistic and not) are known to develop shock singularities in finite-time from smooth data. Such shock formation can be suppressed on cosmological spacetimes whose spatial slices expand at an accelerated rate. However, situations with decelerated expansion, which are relevant in our early universe, are not as well understood. I will present some recent joint work in this direction, based on collaborations with David Fajman, Maciej Maliborski, Todd Oliynyk and Max Ofner.

• Speaker: Zoe Wyatt, DPMMS
• Friday 14 March 2025, 13:00-14:00
• Venue: Potter room / https://cam-ac-uk.zoom.us/j/87235967698.
• Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.

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2025 Scott Lectures - Quantum science with atom-like systems in diamond

Abstract not available

• Speaker: Professor Mikhail Lukin, Harvard University
• Thursday 06 March 2025, 11:00-12:00
• Venue: Cluster Seminar Room, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
• Series: Scott Lectures; organiser: Leona Hope-Coles.

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2025 Scott Lectures - Exploring quantum computing frontier with programmable atom arrays

Abstract not available

Refreshments will be served after the lecture

• Speaker: Professor Mikhail Lukin, Harvard University
• Wednesday 05 March 2025, 16:00-17:00
• Venue: Ray Dolby Auditorium, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
• Series: Scott Lectures; organiser: Leona Hope-Coles.

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2025 Scott Lectures - Lecture 1 New field of quantum science and engineering

Abstract not available

Drinks and nibbles will be served after the lecture

• Speaker: Professor Mikhail Lukin, Harvard University
• Monday 03 March 2025, 16:00-17:00
• Venue: Ray Dolby Auditorium, Ray Dolby Centre, Cavendish Laboratory, JJ Thomson Avenue, CB3 0US.
• Series: Scott Lectures; organiser: Leona Hope-Coles.

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Symmetries and topology of extremal horizons

We establish an intrinsic rigidity theorem for extremal horizons, showing that a compact cross-section of a rotating extremal horizon must admit a Killing vector field. This result holds for a wide class of matter theories, extending work by Dunajski and Lucietti in the vacuum case. In four-dimensional Einstein-Maxwell theory, it follows that any non-trivial cross-section must be given by the extremal Kerr-Newman family. We also discuss the implications for the near-horizon geometry and the topology of cross-sections. This talk is partly based on joint work with David Katona and James Lucietti.

• Speaker: Alex Colling, DAMTP
• Friday 07 March 2025, 13:00-14:00
• Venue: Potter room / https://cam-ac-uk.zoom.us/j/87235967698.
• Series: DAMTP Friday GR Seminar; organiser: Daniela Cors.

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Strong lensing and stellar kinematics of cluster galaxies

As the most massive gravitationally bound structures in the Universe, galaxy clusters frequently act as strong gravitational lenses. Strong lensing (SL) enables us to reconstruct the total mass distribution of a cluster with extreme accuracy, providing insights into the physical properties of dark matter and its interplay with baryons. SL models are also crucial for studying magnified high-redshift sources and measuring cosmological parameters from observed time delays between lensed variable sources. However, the accuracy of SL models is limited by parametric degeneracy, which hinders the reconstruction of the mass distribution of cluster members. This degeneracy can be resolved using independent information from their stellar kinematics. After a general introduction to SL by galaxy clusters, I will present how we leveraged deep MUSE /VLT observations of SL clusters to build a large catalogue of accurate stellar velocity dispersion measurements of early-type member galaxies. These measurements serve as the foundation for calibrating new scaling relations that describe their structure in a set of highly accurate SL models and for comparisons with cosmological hydrodynamical simulations of galaxy clusters, aimed at testing the ΛCDM paradigm.

• Speaker: Giovanni Granata / University of Portsmouth
• Monday 03 March 2025, 13:40-14:05
• Venue: The Hoyle Lecture Theatre + Zoom .
• Series: Institute of Astronomy Seminars; organiser: .

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