arXiv subjects

Aparna Venkatesan

Publications and source records attributed to Aparna Venkatesan.

At least 19 recordsLinked to original sources

arXiv2026

The Outer Space Treaty Won't Save Us From Ourselves

The rapid growth of human activities in outer space sounds urgent alarms around ethical and philosophical issues, particularly concerning space militarization. The present international legal framework governing activities in space, the Outer Space Treaty (OST), views the peaceful exploration of space for scientific research as co-equal to other 'uses' entitled to "due regard" with respect to "potentially harmful interference" on the part of other space actors. The OST is deeply aspirational but has weak enforcement mechanisms, relying at its core on the goodwill of all involved parties as the fundamental basis for accountability. But that framework now faces unsustainable pressures from both public and private interests, and current agreements like the OST may be unable to exert timely, material protections. Terrestrial frameworks of "ethics of deterrence" versus the "ethics of agreements" are quickly expanding into cosmic environments. We argue for the legal recognition of space as an environment as the basis of any future approach to securing its integrity, and share examples of agreements grounded in peaceful cooperative stewardship of shared environments. These represent potential pathways forward that are ethical and also serve rational self-interest and self-preservation at this crucial juncture for humanity.

astro-ph.IM↗

arXiv2023

Noctalgia (sky grief): Our Brightening Night Skies and Loss of Environment for Astronomy and Sky Traditions

Fifty years after the first mention of light pollution in Science, the journal recently elevated this topic to the cover of its 16 June 2023 issue, highlighting the large impact on human and ecological health, circadian rhythms, migratory patterns, and more. We offer here the term noctalgia to express "sky grief" for the accelerating loss of the home environment of our shared skies - representing loss of science, heritage, millennia-old sky traditions, place-based language, and more - and summarize next steps to address the protection of our nighttime and daytime skies.

physics.soc-ph↗

arXiv2023

Aggregate Effects of Proliferating LEO Objects and Implications for Astronomical Data Lost in the Noise

The rising population of artificial satellites and associated debris in low-altitude orbits is increasing the overall brightness of the night sky, threatening ground-based astronomy as well as a diversity of stakeholders and ecosystems reliant on dark skies. We present calculations of the potentially large rise in global sky brightness from space objects, including qualitative and quantitative assessments of how professional astronomy may be affected. Debris proliferation is of special concern: since all log-decades in debris size contribute approximately the same amount of night sky radiance, debris-generating events are expected to lead to a rapid rise in night sky brightness along with serious collision risks for satellites from centimetre-sized objects. This will lead to loss of astronomical data and diminish opportunities for ground-based discoveries as faint astrophysical signals become increasingly lost in the noise. Lastly, we discuss the broader consequences of brighter skies for a range of sky constituencies, equity/inclusion and accessibility for Earth- and space-based science, and cultural sky traditions. Space and dark skies represent an intangible heritage that deserves intentional preservation and safeguarding for future generations.

astro-ph.IM↗

arXiv2022

Reimagining Near-Earth Space Policy in a Post-COVID World

Our planet and our species are at an existential crossroads. In the long term, climate change threatens to upend life as we know it, while the ongoing COVID-19 pandemic revealed that the world is unprepared and ill-equipped to handle acute shocks to its many systems. These shocks exacerbate the inequities and challenges already present prior to COVID in ways that are still evolving in unpredictable directions. As weary nations look toward a post-COVID world, we draw attention to both the injustice and many impacts of the quiet occupation of near-Earth space, which has rapidly escalated during this time of global crisis. The communities most impacted by climate change, the ongoing pandemic, and systemic racism are those whose voices are missing as stakeholders both on the ground and in space. We argue that significant domestic and international changes to the use of near-Earth space are urgently needed to preserve access to - and the future utility of - the valuable natural resources of space and our shared skies. After examining the failure of the U.S. and international space policy status quo to address these issues, we make specific recommendations in support of safer and more equitable uses of near-Earth space.

physics.soc-ph↗

arXiv2021

Semi-analytic forecasts for JWST -- V. AGN luminosity functions and helium reionization at z = 2-7

Active galactic nuclei (AGN) forming in the early universe are thought to be the primary source of hard ionizing photons contributing to the reionization of intergalactic helium. However, the number density and spectral properties of high-redshift AGN remain largely unconstrained. In this work, we make use of physically-informed models calibrated with a wide variety of available observations to provide estimates for the role of AGN throughout the Epoch of Reionization. We present AGN luminosity functions in various bands between z = 2 to 7 predicted by the well-established Santa Cruz semi-analytic model, which includes modelling of black hole accretion and AGN feedback. We then combine the predicted AGN populations with a physical spectral model for self-consistent estimates of ionizing photon production rates, which depend on the mass and accretion rate of the accreting supermassive black hole. We then couple the predicted comoving ionizing emissivity with an analytic model to compute the subsequent reionization history of intergalactic helium and hydrogen. This work demonstrates the potential of coupling physically motivated analytic or semi-analytic techniques to capture multi-scale physical processes across a vast range of scales (here, from AGN accretion disks to cosmological scales). Our physical model predicts an intrinsic ionizing photon budget well above many of the estimates in the literature, meaning that helium reionization can comfortably be accomplished even with a relatively low escape fraction. We also make predictions for the AGN populations that are expected to be detected in future \emph{James Webb Space Telescope} surveys.

astro-ph.GA↗

arXiv2020

Asteroid Resource Utilization: Ethical Concerns and Progress

As asteroid mining moves toward reality, the high bar to entering the business may limit participation and increase inequality, reducing or eliminating any benefit gained by marginalized people or developing nations. Consideration of ethical issues is urgently needed, as well as participation in international, not merely multilateral, solutions.

astro-ph.IM↗

arXiv2020

Ethical Exploration and the Role of Planetary Protection in Disrupting Colonial Practices

We recommend that the planetary science and space exploration community engage in a robust reevaluation concerning the ethics of how future crewed and uncrewed missions to the Moon and Mars will interact with those planetary environments. This should occur through a process of community input, with emphasis on how such missions can resist colonial structures. Such discussions must be rooted in the historical context of the violent colonialism in the Americas and across the globe that has accompanied exploration of Earth. The structures created by settler colonialism are very much alive today, impact the scientific community, and are currently replicated in the space exploration communities' plans for human exploration and in-situ resource utilization. These discussions must lead to enforceable planetary protection policies that create a framework for ethical exploration of other worlds. Current policy does not adequately address questions related to in-situ resource utilization and environmental preservation and is without enforcement mechanisms. Further, interactions with potential extraterrestrial life have scientific and moral stakes. Decisions on these topics will be made in the coming decade as the Artemis program enables frequent missions to the Moon and crewed missions to Mars. Those first choices will have irreversible consequences for the future of human space exploration and must be extremely well considered, with input from those beyond the scientific community, including expertise from the humanities and members of the general public. Without planetary protection policy that actively resists colonial practices, they will be replicated in our interactions and exploration of other planetary bodies. The time is now to engage in these difficult conversations and disrupt colonial practices within our field so that they are not carried to other worlds.

astro-ph.IM↗

arXiv2020

Towards Inclusive Practices with Indigenous Knowledge

Astronomy across world cultures is rooted in Indigenous Knowledge. We share models of partnering with indigenous communities involving Collaboration with Integrity to co-create an inclusive scientific enterprise on Earth and in space.

physics.ed-ph↗

arXiv2020

Semi-analytic forecasts for JWST -- IV. Implications for cosmic reionization and LyC escape fraction

Galaxies forming in low-mass halos are thought to be primarily responsible for reionizing the Universe during the first billion years after the Big Bang. Yet, these halos are extremely inefficient at forming stars in the nearby Universe. In this work, we address this apparent tension, and ask whether a physically motivated model of galaxy formation that reproduces the observed abundance of faint galaxies in the nearby Universe is also consistent with available observational constraints on the reionization history. By interfacing the Santa Cruz semi-analytic model for galaxy formation with an analytic reionization model, we constructed a computationally efficient pipeline that connects `ground-level' galaxy formation physics to `top-level' cosmological-scale observables. Based on photometric properties of the galaxy populations predicted up to $z=15$, we compute the reionization history of intergalactic hydrogen. We quantify the three degenerate quantities that influence the total ionizing photon budget, including the abundance of galaxies, the intrinsic production rate of ionizing photons, and the LyC escape fraction. We explore covariances between these quantities using a Markov chain Monte Carlo method. We find that our locally calibrated model is consistent with all currently available constraints on the reionization history, under reasonable assumptions about the LyC escape fraction. We quantify the fraction of ionizing photons contributed by galaxies of different luminosities and find that the galaxies expected to be detected in JWST NIRCam wide and deep surveys are responsible for producing $\sim 40$-$80\%$ of ionizing photons throughout the EoR. All results presented in this work are available at https://www.simonsfoundation.org/semi-analytic-forecasts-for-jwst/.

astro-ph.GA↗

arXiv2019

Astro2020 APC White Paper: Collaboration with Integrity: Indigenous Knowledge in 21st Century Astronomy

As the oldest science common to all human cultures, astronomy has a unique connection to indigenous knowledge (IK) and the long history of indigenous scientific contributions. Many STEM disciplines, agencies and institutions have begun to do the work of recruiting and retaining underrepresented minorities, including indigenous, Native American and Native Hawaiian professionals. However, with the expansion of telescope facilities on sacred tribal or indigenous lands in recent decades, and the current urgency of global crises related to climate, food/water sovereignty and the future of humanity, science and astronomy have the opportunity more than ever to partner with indigenous communities and respect the wealth of sustainable practices and solutions inherently present in IK. We share a number of highly successful current initiatives that point the way to a successful model of "collaboration with integrity" between western and indigenous scholars. Such models deserve serious consideration for sustained funding at local and institutional levels. We also share six key recommendations for funding agencies that we believe will be important first steps for nonindigenous institutions to fully dialog and partner with indigenous communities and IK to build together towards a more inclusive, sustainable and empowering scientific enterprise.

astro-ph.IM↗

arXiv2019

Astro2020 APC White Paper: Findings and Recommendations from the AAS Committee on the Status of Women in Astronomy: Towards Eliminating Harassment in Astronomy

The Committee on the Status of Women in Astronomy (CSWA) is calling on federal science funding agencies, in their role as the largest sources of funding for astronomy in the United States, to take actions that will end harassment, particularly sexual harassment, in astronomical workplaces. Funding agencies can and should lead the charge to end harassment in astronomy by the 2030 Astrophysics Decadal Survey. Anecdotal and quantitative evidence, gathered both by the CSWA and other groups, shows that harassment is prevalent and damaging for women and minority astronomers and those in related fields. Actions recommended herein will increase the rate of reporting of harassment to agencies and improve their ability to investigate and take action against harassers. We also recommend that agencies participate in harassment prevention by creating and implementing the best anti-harassment education possible. Key recommendations are: - Federal agencies should improve their ethics policies by making harassment a form of scientific misconduct. - Federal agencies should mandate that institutions report to them when a funded Principal Investigator (PI) or co-Principal Investigator (co-PI) is found to be a perpetrator of harassment. - Federal funding agencies should provide online guides to help scientists identify harassment and connect them to the right resources for making confidential or official reports. - Federal agencies should create and ensure the implementation of anti-harassment trainings by making them a requirement of receiving grant funding.

astro-ph.IM↗

arXiv2019

Astro2020 APC White Paper: Findings and Recommendations from the AAS Committee on the Status of Women in Astronomy: Advancing the Career Development of Women in Astronomy

The Committee on the Status of Women in Astronomy (CSWA) is calling on federal science funding agencies, in their role as the largest sources of funding for astronomy in the United States, to take actions that will advance career development and improve workplace conditions for women and minorities in astronomy. Funding agencies can and should lead the charge to produce excellent diversity and inclusion outcomes in our field by the 2030 Astrophysics Decadal Survey. Anecdotal and quantitative evidence, gathered both by the CSWA and other groups, shows that many structural barriers to success remain in our community. We acknowledge the success of programs like NSF-INCLUDES and NSF-ADVANCE and endorse their continued work. We also recommend further action to remove barriers to success for women and minority astronomers. Key recommendations are: - Federal agencies should push academic institutions to reconsider their support systems for scientists by requiring a high standard of pay and benefits. - Federal agencies should fund research and programs that explore and implement strategies for improving the experiences of scientists. - Federal agencies should require Principal Investigators (PIs) to provide plans for creating inclusive work environments and mentoring young scientists.

astro-ph.IM↗

arXiv2019

Astro2020 APC White Paper: Providing a Timely Review of Input Demographics to Advisory Committees

Organizations that support science (astronomy) such as federal agencies, research centers, observatories, academic institutions, societies, etc. employ advisory committees and boards as a mechanism for reviewing their activities and giving advice on practices, policies and future directions. As with any scientific endeavor, there is concern over complementing these committees with enough members who have as broad a range of expertise and understanding as possible, so that bias is mitigated. However, for a number of reasons (logistical, practical, financial, etc.), committees can also not be infinitely large and thus trade-offs must be made. It is often recognized that conflicts of interest must be acknowledged within these committees, but what is not often recognized it the potential for unmitigated biases and "group think" that can be introduced as part of these committees. In this white paper, we recommend that advisory committees that collect community input, (e.g., the Decadal Survey review committee), also collect, compile and review input demographic data before finalizing reports, (e.g., the final 2020 Decadal Survey Report). A summary of these data should be released alongside the final survey report. This information would enable the committee to understand potential "blind spots" and biases of the data collection phase and inform future data collections of any barriers that affect the omission of perspectives from various demographics.

astro-ph.IM↗

arXiv2019

Astro2020 APC White Paper: Tying Research Funding to Progress on Inclusion

The US professional astronomy and astrophysics fields are not representative of the diversity of people in the nation. For example, 2017 AIP reports show that in 2014, women made up only about 20 percent of the faculty in astronomy and physics departments, and the numbers for under-represented minorities (men and women) were, and remain, low. However numerous studies have demonstrated that diverse groups (in both cognition and identity) outperform groups that are more homogeneous, even when the homogeneous group is comprised of all "high achieving experts." (Hong and Page, 2004, Kleinberg and Raghu, 2018). This has been shown to be the case on a variety of complex tasks. Thus, if we want the best opportunity to make progress on and answer the research questions of the 2020s, we must employ diverse teams who bring different heuristics and perspectives to those problems. However, currently in the field there are few tangible motivations to encourage projects, missions or programs to employ teams that are diverse in both cognitive areas and identity to take on these complex problems. Managing groups and organizations contracted to run these efforts are currently not required or incentivized to employ an identity diverse workforce. In this position (white) paper, we recommend that agency funding (from NSF, NASA, DOE, etc.), especially for missions, projects and programs, encourage the development and retention of diverse teams by requiring documentation of and progress on metrics related to diversity, inclusion and equity. We further recommend that documented progress on diversity and inclusion metrics should be monitored in reviews alongside project management and budget reporting. Managing groups and organizations proposing to administer projects on behalf of agencies should be required to demonstrate competency with respect to diversity and inclusion metrics.

astro-ph.IM↗

arXiv2019

Primarily Undergraduate Institutions and the Astronomy Community

This White Paper highlights the role Primarily Undergraduate Institutions (PUIs) play within the astronomy profession, addressing issues related to employment, resources and support, research opportunities and productivity, and educational and societal impacts, among others. Astronomers working at PUIs are passionate about teaching and mentoring undergraduate students through substantive astronomy experiences, all while working to continue research programs that contribute to the advancement of the professional field of astronomy. PUIs are where the majority of undergraduate students pursue post-secondary education, and as such, understanding the unique challenges and opportunities associated with PUIs is critical to fostering an inclusive astronomy community throughout the next decade. We provide a view of the profession as lived and experienced by faculty and students of PUIs, while highlighting the unique opportunities, challenges, and obstacles routinely faced. A variety of recommendations are outlined to provide the supporting structures and resources needed for astronomy to thrive at PUIs over the next decade and beyond - a critical step for a profession focused on fostering and maintaining an inclusive, supportive, and diverse community.

astro-ph.IM↗

arXiv2019

Integrating Undergraduate Research and Faculty Development in a Legacy Astronomy Research Project

The NSF-sponsored Undergraduate ALFALFA Team (UAT) promotes long-term collaborative research opportunities for faculty and students from 23 U.S. public and private primarily undergraduate institutions (PUIs) within the context of the extragalactic ALFALFA HI blind legacy survey project. Over twelve project years of partnering with Arecibo and Green Bank Observatories, the UAT has had a demonstrable impact on the health of a legacy astronomy project, science education, and equity/inclusion in astronomy, with successful outcomes for 373 UAT students (39% women; ~30% members of underrepresented groups) and 34 faculty (44% women). The UAT model is adaptable to many large scientific projects and can be supported by relatively modest funding. We recommend that granting agencies identify funding resources to support the model, either as an add-on to legacy grant support or as a stand-alone funding source. This could include encouragement of UAT-like components in large scale projects currently being developed, such as the LSST and TMT. By doing this, we will recognize the high numbers of astronomy research-trained heavy-teaching-load faculty at PUIs as an under-utilized resource of the astronomy community (see also White Paper by Ribaudo et al.). These members of our community have the skills and the strong desire to contribute meaningfully to their field, as well as the ability to encourage and interact closely with many talented and motivated undergraduate students from all backgrounds.

astro-ph.IM↗

arXiv2019

Cosmic Dawn and Reionization: Astrophysics in the Final Frontier

The cosmic dawn and epoch of reionization mark the time period in the universe when stars, galaxies, and blackhole seeds first formed and the intergalactic medium changed from neutral to an ionized one. Despite substantial progress with multi-wavelength observations, astrophysical process during this time period remain some of the least understood with large uncertainties on our existing models of galaxy, blackhole, and structure formation. This white paper outlines the current state of knowledge and anticipated scientific outcomes with ground and space-based astronomical facilities in the 2020s. We then propose a number of scientific goals and objectives for new facilities in late 2020s to mid 2030s that will lead to definitive measurements of key astrophysical processes in the epoch of reionization and cosmic dawn.

astro-ph.GA↗

arXiv2016

The LyA-LyC Connection: Evidence for an Enhanced Contribution of UV-faint Galaxies to Cosmic Reionization

The escape of ionizing Lyman Continuum (LyC) photons requires the existence of low-N_HI sightlines, which also promote escape of Lyman-Alpha (Lya). We use a suite of 2500 Lya Monte-Carlo radiative transfer simulations through models of dusty, clumpy interstellar (`multiphase') media from Gronke & Dijkstra (2016), and compare the escape fractions of Lya [f_esc(Lya)] and LyC radiation [f_esc(LyC)]. We find that f_esc(LyC) and f_esc(Lya) are correlated: galaxies with a low f_esc(Lya) consistently have a low f_esc(LyC), while galaxies with a high f_esc(Lya) exhibit a large dispersion in f_esc(LyC). We argue that there is increasing observational evidence that Lya escapes more easily from UV-faint galaxies. The correlation between f_esc(LyC) and f_esc(Lya) then implies that UV-faint galaxies contribute more to the ionizing background than implied by the faint-end slope of the UV-luminosity function. In multiphase gases, the ionizing escape fraction is most strongly affected by the cloud covering factor, f_cl, which implies that f_esc(LyC) is closely connected to the observed Lya spectral line shape. Specifically, LyC emitting galaxies typically having narrower, more symmetric line profiles. This prediction is qualitatively similar to that for `shell models'.

astro-ph.CO↗