Details of the talks 

Talks on August 21

Morning Session

1. Speaker: Tejaswi V. Nerella 

Talk Title: The LIGO-VIRGO gravitational wave detections and their implications for cosmology

Abstract: The LIGO and VIRGO interferometers have detected ~100 gravitational wave signals from merging compact binaries in their first three observing runs. This rich haul of events has given us a view of the astrophysical population of stellar remnants such as neutron stars and black holes, and a trove of insights into the behavior of gravity in the strong-field regime. The detections also form a new population of astrophysical sources out to cosmological distances, enabling new constraints on cosmological parameters. I will provide an overview of what we have learned from the detections so far, and touch upon what we can expect to learn from observing runs with improved future detectors.

2. Speaker: A Gopakumar

Talk Title: Pulsar Timing Array Efforts and Their Implications

Abstract: Maturing Pulsar timing arrays monitor millisecond pulsars which can be converted into Einstein clocks to search for perturbations due to gravitational waves at nanohertz frequencies. Very recent independent and  coordinated investigations by the established Pulsar Timing Array collaborations strongly indicate that the universe is humming with gravitational radiation-a very low-frequency rumble that rhythmically stretches and compresses spacetime and the matter embedded in it. This stochastic GW signal is consistent with that expected from an ensemble of supermassive black hole binaries, but could also be attributable to more exotic sources. We will discuss the astrophysical and cosmological implications of ongoing IPTA efforts.

Pre-lunch Session

1. Speaker: Tanvi Karwal

Talk title: Theoretical solutions to cosmic tensions 

Abstract: The standard LCDM model of cosmology is discrepant when its parameters are constrained using early- vs. late-universe observations. Specifically, two intriguing tensions have emerged - the Hubble and the weak-lensing S8 tensions, which may hint at new physics. I have worked extensively on interpreting the Hubble tension as arising from new physics, proposing one of the most successful models to resolve the tension - early dark energy (EDE), which inspired several similar models in the literature. I have also phenomenologically explored the S8 tension and in this talk, I will present my learnings - theoretical insights into resolving the tensions, challenges to models beyond LCDM and applications of this research to questions beyond cosmic anomalies. 

2. Speaker: Oliver Philcox

Talk title: The Cosmological Particle Collider

Abstract: Can we build a particle accelerator the size of the Universe? Recent work has shown that cosmology can provide a unique insight into inflationary physics, with the distribution of primordial fluctuations encoding particle interactions at energies far larger than those probed on Earth. I will discuss new developments in this field, which combine inflationary physics with theoretical modelling of galaxy surveys, allowing for the first constraints to be placed on ultra-high-energy physics from late-Universe data.

Post-lunch Session

1. Speaker: L Sriramkumar

Talk title: Constraining the history of reheating with the NANOGrav 15-year data

Abstract: Over the last few years, primordial black holes (PBHs) have emerged as a strong candidate for cold dark matter. A significant number of PBHs are produced when the strength of the primordial scalar power spectrum is enhanced on small scales (compared to the CMB normalized values on large scales). Such primordial spectra also inevitably lead to strong amplification of the scalar-induced, secondary gravitational waves (GWs) at higher frequencies. The recent detection of the stochastic gravitational wave background (SGWB) by the pulsar timing arrays (PTAs) has opened up the possibility of directly probing the very early universe. Different studies have shown that, when PBHs are assumed to have been formed during the epoch of radiation domination, the mechanism for the amplification of the scalar-induced GWs that is required to explain the PTA data can overproduce the PBHs over some ranges of masses. In this talk, considering a specific functional form for the primordial scalar power spectrum, I describe the production of PBHs and the scalar-induced secondary GWs during the phase of reheating, which precedes the standard epoch of radiation domination. Specifically, I discuss the manner in which we account for the uncertainties in the conditions for the formation of PBHs to ensure that the extent of PBHs produced remains within the observational bounds. Finally, I show that the scalar-induced SGWB generated during a phase of reheating with a steeper equation of state (than that of radiation) fits the NANOGrav 15-year data with a stronger Bayesian evidence than the astrophysical scenario involving GWs produced by merging supermassive binary black holes.

2. Speaker: Subhendra Mohanty

Talk Title: Gravitational memory signal as a probe of the quantum nature of the graviton

Abstract: I will discuss how the gravitational wave memory signal which is related to the soft-graviton theorems can be used for probing the quantum nature of gravitons.

3. Speaker: Subinoy Das

Talk Title: Hint of fifth force in dark sector and recent DESI resultSI result.

Abstract: Existence of a  possible long range fifth force in dark energy-dark matter sector  have been explored in many studies which evades different observational constraints. We will present one such simple generic model  of fifth force in dark sector responsible for acceleration of the universe. We will present constraints on such model   with  diverse datasets such as Planck, BAO, Pantheon+, and SH0ES. Our results, for the first time, reveal a discernible detection of a fifth force in dark sector. We will also present how present DESI result about evolving dark energy  can be captured in such models.

Afternoon Session 

1. Speaker: Arka Banerjee

Talk title: Cosmology beyond the 2-point function: k-Nearest Neighbor Distributions

Abstract: As cosmological surveys continue to provide exquisite data about our Universe across various wavelengths, a crucial question to ask ourselves is how to use this data to answer the major questions in cosmology - the origin and fate of the Universe, the various components that make up the Universe, and their microphysical description. This is typically done by compressing petabytes of original data into effective “summary statistics” that can be compared against theoretical predictions. More informative summaries of the data allow us to better constrain theoretical models using the same original data. I will introduce a novel and powerful summary statistic - the k-Nearest Neighbor (kNN) distribution. I will show its current applications to various cosmological datasets, outperforming inferences using other summary statistics. I will then show how the kNN framework is ideally suited to connect the disparate languages of the different existing summary statistics, thereby allowing for a thorough quantitative study of their relative information content.

2. Speaker: Divya Rana

Talk Title: Invisible sirens: Expansion rate of the universe using binary black hole mergers

Abstract: Binary neutron star (BNS) mergers have introduced a new method for measuring the expansion rate of the universe by combining luminosity distance measurements from gravitational wave events with the redshift of their electromagnetic counterparts to constrain the Hubble constant. Although binary black hole mergers, which lack electromagnetic counterparts, are more common, we can statistically constrain their redshift distribution by cross-correlating these events with galaxies. Using an all-sky simulated gravitational wave event catalogue and mock galaxies, we demonstrate that clustering gravitational wave events with galaxies can effectively constrain the Hubble parameter. I will discuss our efforts to use the DESI Imaging Legacy Survey galaxy catalogue to detect this cross-correlation with real data, present gravitational wave simulations with O4 sensitivities and the latest population models, and forecast the number of events needed to reliably detect the cross-correlation signal between gravitational wave events and galaxies.

3. Speaker: Sukannya Bhattacharya

Talk Title: Gravitational waves and 1-loop correction to the scalar power spectrum from sharp turns during                                      inflation

Abstract: Despite the stringent constraints on the primordial power spectra from the Cosmic Microwave Background (CMB) on large cosmological scales, the dynamics at small scales during the primordial epoch of inflation remain hitherto unconstrained. During inflation, scalar and tensor fluctuations can grow via various interesting mechanisms, which can result in the formation of abundant primordial black holes (PBH) after inflation and can induce large tensor fluctuations, which are realised as a stochastic background of induced gravitational waves (GW). With the tremendous sensitivities proposed by upcoming GW surveys and several bounds on the abundance of PBH over a huge range of masses, it is exciting to analyse relevant inflation models for their predictions for PBH and induced GW. In light of recent advances in this field of research, in this talk I will discuss consequences of a specific multi-field model of inflation containing sharp turns in the field space and relevant 1-loop correction to the scalar power spectrum.

4. Speaker: Mohit Raj Sah

Talk Title: Cosmology of the supermassive black holes using anisotropic nHz gravitational wave

Abstract: The formation and evolution of supermassive black holes (SMBHs) remain an open question in cosmology. Detecting nanohertz (nHz) gravitational waves (SMBHBs) via pulsar timing arrays (PTAs) offers a promising method for studying SMBH formation over cosmic time. The gravitational wave (GW) background generated by the superposition of the GWs from individual supermassive black hole binaries (SMBHBs) is expected to be anisotropic in nature.  Moreover, since these binaries reside at the center of galaxies, the distribution of the anisotropic signal is expected follow the galaxy distribution in the universe. Therefore, the study of the angular power spectrum of the stochastic gravitational wave background (SGWB)  as well as the cross-correlation of the SGWB signal with galaxy distribution presents a promising avenue for investigating cosmic evolution of the SMBH. Different population models are expected to exhibit different signatures on both the auto and cross-power spectrum of the SGWB signal making it possible to put valuable constraints on the population of the SMBH over cosmic time.

Talks on August 22 

Morning Session

1. Speaker: Suhail Dhawan

Talk title: H0 tension: Observational Status

Abstract: There are several complementary measurements of the local value of the Hubble constant. I will summarise the current status of the measurements and provide an outlook for the near future. I will summarise the latest constraints from independent distance ladders and the role of Type Ia supernovae in next generation measurements. 

2. Speaker: Shi Pi

Talk title: Generation of PBHs in inflationary scenarios: A review and recent progress

Abstract: Primordial black holes (PBHs) are formed in the very early universe well before recombination, if the density perturbation is high at its horizon reentry. After reviewing the inflation models which enhance the power spectrum of the curvature perturbation to generate such PBHs as well as scalar-induced gravitational waves (SIGWs), I will talk about the recent progress on the non-Gaussian effect in such a field. I will also talk about the implications on the current and upcoming observational constraints.

Pre-lunch Session

1. Speaker: Shadab Alam

Talk Title: Mapping the Cosmos: Frontiers in Galaxy Surveys

Abstract: This talk will explore the evolving landscape of galaxy surveys, from their historical foundations to current methodologies and future prospects. We'll discuss key techniques in measuring cosmic structure and their implications for our understanding of the universe. Recent results from ongoing surveys will be presented, offering fresh perspectives on longstanding cosmological questions. The presentation will also touch upon upcoming observational projects and the challenges they aim to address. By examining the interplay between galaxies and their environments, we'll highlight the critical role of galaxy surveys in advancing our cosmological model and unraveling the mysteries of dark energy and dark matter.

2. Speaker: Pratika Dayal 

Talk Title: The emergence of galaxies in the first billion years: implications for reionization, cosmology and                                       gravitational wave astronomy

Abstract: Galaxy formation in the first billion years marks a time of great upheaval in our cosmic history: the first sources of light in the Universe, these galaxies ended the 'cosmic dark ages' and produced the first photons that could break apart the hydrogen atoms suffusing all of space starting the process of 'cosmic reionization'. The past few years have seen cutting-edge instruments such as the James Webb Space Telescope (JWST) provide tantalising glimpses of such galaxies assembling in an infant Universe. Puzzlingly, these observations are also yielding a sample of unexpectedly numerous and large black holes (up to a 100 million solar masses) within the first 600 million years, posing an enormous challenge for galaxy formation models. I will show how this data is providing an unprecedented opportunity to pin down the reionization state of the Universe in addition to providing an unrivalled resource for understanding the reionization topology in the forthcoming era of 21cm cosmology. I will also show how these early systems provide a powerful testbed for Dark Matter models beyond "Cold Dark Matter". Finally, I will try to give a flavour of the gravitational wave event rates expected from such early black holes in the Laser Interferometer Space Antenna Array (LISA) era.  

Post-lunch Session

1. Speaker: Tirthnkar Roy Choudhury

Talk title: Studying the first stars using SKA and other upcoming facilities

Abstract: Studying the first stars using the Square Kilometre Array (SKA) and other upcoming facilities promises to revolutionize our understanding of cosmic dawn and the epoch of reionization. The SKA, with its unprecedented sensitivity and resolution, will allow us to probe the 21 cm hyperfine transition of neutral hydrogen, offering a direct observational window into the era when the first stars and galaxies ionized the intergalactic medium. This will be complemented by data from other cutting-edge facilities such as the James Webb Space Telescope (JWST), which will provide high-resolution infrared observations of the earliest galaxies, and the next generation of ground-based optical telescopes, which will enable detailed spectroscopic studies of the chemical compositions and formation mechanisms of the first stellar populations. Together, these instruments will synergize to provide a multi-wavelength, multi-messenger approach to studying the first stars, enabling precise constraints on their formation rates, initial mass functions, and the role they played in reionization. This comprehensive dataset will not only test theoretical models of early star formation and galaxy evolution but also refine our understanding of the feedback processes that governed the transition from the cosmic dark ages to the ionized universe we observe today.

Afternoon Session 

1. Speaker: Arindam Chatterjee

Talk title: Probing Dark Matter Interactions in the Light of CMBR

Abstract: In the standard cosmology, Dark Matter (DM) is generally assumed to be non-interacting. However, in several well-motivated particle physics models, which include a DM candidate, it participates in various interactions. In particular, we have considered interactions of DM with neutrinos and electrons. Such interactions, if present in the early Universe, can leave imprints in the anisotropies observed in the Cosmic Microwave Background Radiation (CMBR). We have investigated such scenarios in light of CMBR data from the Planck collaboration. Considering specific forms of interactions, we further obtain the constraints on the relevant lagrangian parameters. [Based on an upcoming work and JCAP10(2021)017]

2. Speaker: Ruchika

Talk title: BAO Anomalies after DESI release

Abstract: In the era of tensions, when precision cosmology is blooming, numerous new theoretical models are emerging. However, it is crucial to pause and question the extent to which the observational data we rely on are model-dependent. I will talk about the comoving position of the acoustic peak, a cornerstone standard ruler in cosmology. We considered BAO observational datasets from two distinct teams and calculated the product $hr_d$ with the help of each BAO data set along with SN I-a data from the Pantheon Plus sample. We summarize our findings into three main results, (i) 2D BAO measures $hr_d$ higher than 3D BAO and DESI analyses under standard $\Lambda$CDM cosmology (ii) Using 2D BAO, a higher $H_0$ compatible with SH0ES and a higher sound horizon $r_d$ (compatible with Planck) can be achieved even within  $\Lambda$CDM framework, due to the inherent higher product in 2D BAO analysis. Therefore, 2D BAO should be used cautiously while proposing new theoretical models to address the Hubble tension. And (iii) assuming no systematics in both BAO datasets, interpreting $\Omega_{m0}-hr_d$ plane may require physics beyond $\Lambda$CDM not just while using observational BAO data but also while observing and interpreting it.

3. Speaker: Amlan Chakraborty

Talk title: Cosmological Constraints on Mass-Varying Dark Matter

Abstract: As an alternative to Cold Dark Matter (CDM), the hot dark matter has been ruled out because of its excessive free streaming. However, Warm Dark Matter (WDM) has been well studied in the literature, where it becomes non-relativistic as the universe cools down. But we propose a model of dark matter (DM), which is neither hot nor warm, where the mass of the DM varies with redshift, and it starts to behave like CDM after it becomes non-relativistic. We show that for this model, the S8 tension is significantly reduced, a lower bound on the transition redshift, and a detection of mass of the DM around 40.6 eV. Many particle physics models for this kind of DM have been proposed in the past. Still, it has to be explored in detail as it has interesting cosmological implications that can be detected in next-generation experiments like CMB 4, etc.

4. Speaker: Jonathan Schiff

Talk title: Rethinking Recombination: Primordial Magnetic Fields and the Hubble tension

Abstract: Perhaps the most significant challenge to the widely successful Lambda-CDM theory is the disagreement between late and early Universe measurements of the present day Hubble expansion rate (H0), referred to as the Hubble tension. One of the ways to resolve the Hubble tension is to modify the recombination history of the early universe. An intriguing proposal to realize this invokes primordial magnetic fields (PMFs) to stir up the plasma on small scales and speed up recombination. An earlier recombination shrinks the sound horizon at the surface of last scattering and consequently increases the early Universe inference of H0. On the small scales at which PMFs introduce baryon clumping, the nonlocal transport of photons in the Lyman-alpha resonance and Lyman-continuum, which mediate the recombination process, becomes important. Utilizing a linearized scheme for magnetohydrodynamics in the early Universe, our work provides a self-consistent and computationally inexpensive treatment of the evolution of PMF-induced small-scale inhomogeneities from magnetogensis to and through Recombination incorporating nonlocal radiative transport.

Talks on August 23 

Morning Session

1. Speaker: Saurabh Singh

Talk title: Seeing the Universe in 21-cm wavelength

Abstract: There are several poorly constrained periods over cosmic evolution. Formation of first stars and galaxies, followed by reionization of the intergalactic medium is one such epoch. Often referred to as "cosmic dawn", observing this period is extremely challenging due to the faint nature of the signals originating from it. The redshifted 21-cm line from neutral hydrogen offers one such possibility to observe the cosmic dawn and extract information about the nature of first stars and galaxies. In this talk, I will discuss our attempts at detecting the 21-cm signal from cosmic dawn. I will elaborate the challenges involved in detecting faint cosmological signals, and how our in-house designed experiments address those challenges. I will finally discuss the recent results from our observations, and explore how 21-cm signal can also be employed to probe other cosmic mysteries at different redshifts.

2. Speaker: Surhud More

Talk title: The sigma8 tension: observational status

Abstract: I will present the observational status for the sigma8 tension with respect to various observational probes including weak gravitational lensing, clustering, and galaxy clusters.

Pre-lunch Session

1. Speaker: Sherry Suyu

Talk title: Strongly lensed transients as a probe of cosmology

Abstract: Strong gravitational lenses with measured time delays between the multiple lensed images provide an effective way to measure the Hubble constant H0, a key cosmological parameter that sets the expansion rate of the Universe.  Independent determinations of H0 are important to assess the recent tensions between different measurements of H0, which if verified, would imply new physics beyond the standard cosmological model.  Lensed quasars with exquisite observations have been used to measure H0, providing competitive results. Exciting discoveries of the first strongly lensed supernovae offer new opportunities for measuring H0, and I will present recent advances. I will show the bright prospects of lensed transients as an independent and competitive cosmological probe.

2. Speaker: Eleonora Di Valentino

Talk title: Unraveling the Hubble constant tension

Abstract: The standard Lambda Cold Dark Matter cosmological model has been incredibly successful in explaining a wide range of observational data, from the cosmic microwave background radiation to the large-scale structure of the universe. However, recent observations have revealed several inconsistencies among the model's key cosmological parameters, each with varying levels of statistical significance. In my talk, I'll specifically delve into the H0 tension, outlining the challenges encountered in addressing this persistent issue. In particular I will review the H0 puzzle, highlighting some interesting extended cosmological scenarios that could potentially alleviate it. However, I will also discuss the limitations of these proposed solutions and note that none have successfully resolved this discrepancy.

Post-lunch Session

1. Speaker: Mayukh Raj Gangopadhyay

Talk title: Confronting Modified Gravity Models with the sine qua non: BBN 

Abstract: The idea of modification of Albert Einstein’s General Relativity dates back to the first few months after the seminal paper published by Einstein. The proposals were made to extend GR and incorporate it into a larger, more unified theory such as Eddington’s theory of connections, and Weyl’s scale-independent theory. Any modification implies a change in the expansion rate thus affecting the freeze-out temperature. These nuclear reaction rates and abundances during the BBN epoch are affected. As nuclear abundances are remarkably constrained through experiments, the modification in gravity should get the most stringent bound from BBN. In this talk, I will review this and point out how in very few cases a deviation from the standard thermal history of the Universe can resolve the remaining perplexity in BBN: The Lithium problem.

2. Speaker: Upala Mukhopadhyay

Talk title: Understanding dark energy from the scale factor parametrisation

Abstract: We propose and implement a novel test to assess deviations from well-established concordance ΛCDM cosmology while inferring dark energy properties. In contrast to the commonly implemented parametric forms of the dark energy equation-of-state (EoS), we test the validity of the cosmological constant on the more fundamental scale factor [a(t)] which determines the expansion rate of the Universe. We constrain our extended ‘general model’ for the expansion history using the late-time cosmological observables, namely Baryon Acoustic Oscillations (BAO) and Supernovae. As a primary inference, we contrast the BAO compilations from the completed SDSS and the more recent DESI. We find that the former deviates from the ΛCDM scenario at a mild ∼ 2σ level while the latter is completely consistent with the standard picture when the dark energy properties are inferred. We find that the posterior of the dark energy EoS is mainly constrained to be quintessence-like, however, we demonstrate the rich phenomenology of dark energy behaviour that can be obtained in our general model wrt to the ΛCDM.

3. Speaker: Shahnawaz Aryan Adil

Talk title: Cosmological tensions and new physics in the Dark Energy sector

Abstract: Recent developments in cosmology have revealed inconsistencies in the measurement of various cosmological parameters such as $H_0$ and $S_8$, leading to what is commonly referred to as cosmological tensions. These tensions may be originated from statistical uncertainties or theoretical inadequacies. Notably, advancements in measurements by experiments such as SH0ES, DES, and SPT suggest potential shortcomings in the standard $\Lambda$CDM cosmological model. My study focuses on exploring alternatives to the standard model, particularly within a specific class characterized by a Negative Cosmological Constant. I work on Bayesian estimation techniques to assess the viability of these models as potential resolutions to the observed discrepancies.

4. Speaker: Yashi Tiwari

Talk title: Towards a possible solution to the Hubble tension with Horndeski gravity

Abstract: The Hubble tension refers to the discrepancy in the value of the Hubble constant $H_0$ inferred from the cosmic microwave background observations, assuming the concordance $\Lambda$CDM model of the Universe, and that obtained from the distance ladder and other direct measurements. In order to alleviate this tension, we construct a plausible dark energy scenario within the framework of Horndeski gravity. A dynamical dark energy scalar field with self-interactions and non-minimal coupling to gravity drives the late-time accelerated expansion of the universe. The non-trivial features of the model are phantom behaviour at low redshifts, negative dark energy density at high redshifts and evolution in the effective gravitational constant. We show that for appropriate choices of parameters, the model serves as a promising scenario to alleviate the Hubble tension. We confront the predictions of the model with low redshift observations from Supernovae, distance ladder measurements of $H_0$, cosmic chronometers and baryon acoustic oscillations to obtain best-fit constraints on model parameters. Additionally, we explore the model's implications for the growth of cosmic structures, incorporating data from weak lensing and redshift space distortions, aiming for a potential resolution of the $S_8$​ tension.

Afternoon Session 

1. Speaker: Atrideb Chatterjee

Talk title: Cosmology from Point Cloud

Abstract: In this talk, I will discuss our recent study where we train a novel deep learning architecture to perform likelihood-free inference on the value of the cosmological parameters from halo catalogs of the Quijote N-body simulations. Our model takes as input a halo catalog where each halo is characterized by its position, mass, and velocity moduli. By construction, our model is E(3) invariant and is designed to extract information hierarchically. Unlike graph neural networks, it does not require the transformation of the input halo (or galaxy) catalog into a graph. Given its simplicity, our model can process point clouds with large numbers of points. We discuss the advantages of this class of methods but also point out its limitations and potential ways to improve them for cosmological data.

2. Speaker: Purba Mukherjee

Talk title: Model-independent cosmological inference post DESI DR1 BAO measurements

Abstract: In this work, we have implemented Gaussian process regression to reconstruct the expansion history of the universe in a model agnostic manner, using the Pantheon-Plus SN-Ia compilation in combination with two different BAO measurements (SDSS-IV and DESI DR1). In both the reconstructions, the ΛCDM model is always included in the 95% confidence intervals. We find evidence that the DESI LRG data at zeff = 0.51 is not an outlier within our model-independent framework. We study the Om-diagnostics and the evolution of the total equation of state (EoS) of our universe, which hint towards the possibility of a quintessence-like dark energy scenario with a very slowly varying EoS, and a phantom-crossing in higher z. The entire exercise is later complemented by considering two more SN-Ia compilations - DES-5YR and Union3 - in combination with DESI BAO. Reconstruction with the DESI BAO + DES-5YR SN data sets predicts that the ΛCDM model lies outside the 3σ confidence levels, whereas with DESI BAO + Union3 data, the ΛCDM model is always included within 1σ. We also report constraints on H0rd from our model-agnostic analysis, independent of the pre-recombination physics. Our results point towards an ≈ 2σ discrepancy between the DESI + Pantheon-Plus and DESI + DES-5YR data sets, which calls for further investigation

3. Speaker: Shiladitya Porey

Talk title: Does JWST data point towards a log-normal mass function for PBHs?

Abstract: Recent data from HST and JWST observations have uncovered quasars and well-developed galaxies at earlier redshifts than expected. This early formation can be explained by seeding these galaxies with massive primordial black holes (PBHs), a concept proposed by Dolgov & Silk (PRD 47,1993). Their model predicts a log-normal mass function for PBHs, which aligns well with current observations. In this talk, i will discuss that adjustments to the log-normal mass spectrum, based on supermassive black hole data, suggest that PBHs constitute a significant fraction of dark matter, with a peak mass around ~O(10 M⊙). Additionally, the chirp mass distribution from LIGO/Virgo's O1-O3 runs supports a peak around 17M⊙.