About

Antonella Palmese is an astrophysicist at Carnegie Mellon University in Pittsburgh. Her research group focuses on multi-messenger analyses, primarily involving optical and near-infrared observations of transients and galaxies, as well as gravitational waves from compact object binaries detected by LIGO, Virgo, and KAGRA. The group is also engaged in supernova searches and cosmology, along with studies of sources for the space-based gravitational wave interferometer LISA. Through these efforts, Palmese and her team contribute to advancing the understanding of gravitational wave events, their electromagnetic counterparts, and the broader astrophysical phenomena associated with compact object mergers and transient sources.

Research topics

• Physics
• Astrophysics
• Astronomy
• Theoretical physics
• Computer Science
• Particle physics
• Quantum mechanics
• Artificial Intelligence
• Statistics
• Chemistry
• Classical mechanics
• Mathematical physics
• Psychology
• Optics

Selected publications

• Dark Energy Survey Year 6 Results: Weak Lensing and Galaxy Clustering Cosmological Analysis Framework

  HAL (Le Centre pour la Communication Scientifique Directe) · 2026-01-21

  preprintOpen access

  We present the methodology for the weak lensing and galaxy clustering analyses of the Dark Energy Survey (DES) Year 6 data set. In this work, we design and validate the analysis pipeline for the cosmic shear, galaxy clustering plus galaxy$-$galaxy lensing ($2 \times 2$pt), and the joint analysis in the $3 \times 2$pt. Our framework accounts for key theoretical uncertainties, such as baryonic feedback and galaxy bias, incorporating both linear and non-linear models. We apply scale cuts in regimes where theoretical modeling becomes unreliable. The robustness of the pipeline is validated using mock data and simulations, confirming unbiased cosmological constraints and highlighting the importance of posterior projection effects in the validation process. As a result, we deliver robust and validated analysis pipelines for cosmic shear, $2 \times 2$pt, and $3 \times 2$pt in $Λ$CDM and $w$CDM scenarios, including a well-defined set of scales suitable for real data analysis, a robust prescription for theoretical systematics, and the theoretical covariance of the signal. This comprehensive methodology also lays the groundwork for future galaxy surveys such as the Vera C. Rubin Observatory Legacy Survey of Space and Time.

  PublisherOA PDFDOI

• Detecting Prompt and Afterglow Jet Emission of Gravitational-wave Events from LIGO/Virgo/KAGRA and Next-generation Detectors

  The Astrophysical Journal · 2026-03-13

  preprintOpen access

  Abstract Following the wealth of new results enabled by multimessenger observations of the binary neutron star (BNS) merger GW170817, the next goal is increasing the number of detections of electromagnetic counterparts to gravitational-wave (GW) events. We study the detectability of the prompt emission and afterglows produced by the relativistic jets launched by BNS mergers that will be detected by LIGO–Virgo–KAGRA during their fifth observing run (O5), and by next-generation (XG) GW detectors (Einstein Telescope and Cosmic Explorer). We quantify the impact of various BNS merger and jet afterglow parameters on the likelihood of detection, focusing on the impact of the observer’s viewing angle and the jet’s core half-opening angle. We explore detectability over a wide range of current state-of-the-art facilities (e.g., the James Webb Space Telescope, Chandra X-ray Observatory) as well as upcoming XG facilities (e.g., AXIS, NewAthena, ngVLA, SKA). We find that a few GW events (∼ 0–4) per year may have a detectable afterglow component in O5, with the largest detection rates expected with SKA in the radio and JWST in the near-infrared. In the XG era, hundreds of multimessenger detections of afterglows per year may be possible with a range of instruments, such as NewAthena in the X-ray and ngVLA in the radio. While zero to a few GW events per year are expected to be accompanied by a detectable prompt emission in O5, dozens per year may be detectable in XG.

  PublisherDOI

• Identifying Anomalous DESI Galaxy Spectra with a Variational Autoencoder

  Monthly Notices of the Royal Astronomical Society · 2026-01-06

  preprintOpen access

  ABSTRACT The tens of millions of spectra being captured by the Dark Energy Spectroscopic Instrument (DESI) provide tremendous discovery potential. In this work we show how Machine Learning, in particular Variational Autoencoders (VAE), can detect anomalies in a sample of approximately 200 000 DESI spectra comprising galaxies, quasars and stars. We demonstrate that the VAE can compress the dimensionality of a spectrum by a factor of 100, while still retaining enough information to accurately reconstruct spectral features. We detect anomalous spectra as those with high reconstruction error and those which are isolated in the VAE latent representation. The anomalies identified fall into two categories: spectra with artefacts and spectra with unique physical features. Awareness of the former could improve the DESI spectroscopic pipeline; whilst the latter could help us discover new and unusual objects. To further curate the list of outliers identified, we use the Astronomaly package which employs Active Learning to provide personalized outlier recommendations for visual inspection. In this work we also explore the VAE latent space, finding that different object classes and subclasses are separated despite being unlabelled. We inject controlled synthetic anomalies and analyse their locations in the latent space to illustrate how the VAE responds to atypical spectral features; and we demonstrate the interpretability of this latent space by identifying tracks within it that correspond to various spectral characteristics. In upcoming work we hope to apply the methods presented here to search for both systematics and astrophysically interesting objects in much larger datasets of DESI spectra.

  PublisherDOI

• AT2025ulz and S250818k: Leveraging DESI Spectroscopy in the Hunt for a Kilonova Associated with a Subsolar-mass Gravitational-wave Candidate

  The Astrophysical Journal Letters · 2026-04-09

  articleOpen access

  Abstract On 2025 August 18, the LIGO–Virgo–KAGRA collaboration reported a subthreshold gravitational-wave candidate detection consistent with a subsolar-mass neutron star merger, denoted S250818k. An optical transient, AT2025ulz, was discovered within the localization region. AT2025ulz initially appeared to meet the expected behavior of kilonova emission, the telltale signature of a binary neutron star merger. The transient subsequently rebrightened after ∼5 days and was classified as a Type IIb supernova. In this work, we analyze the observations of its host galaxy obtained by the Dark Energy Spectroscopic Instrument (DESI). From the DESI spectrum, we obtain a secure redshift of z = 0.084840 ± 0.000006. If S250818k has an astrophysical origin, this places the transient within 2 σ of the gravitational-wave distance and results in an integral overlap between the gravitational-wave alert and the transient location of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>log</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> </mml:msub> <mml:mi class="MJX-tex-calligraphic" mathvariant="script">I</mml:mi> <mml:mo>≈</mml:mo> <mml:mn>3.9</mml:mn> <mml:mo>−</mml:mo> <mml:mn>4.2</mml:mn> </mml:math> . Our analysis of the host galaxy’s spectral energy distribution reveals a star-forming, dusty galaxy with stellar mass ∼10 10 M ⊙ , broadly consistent with the population of both short gamma-ray bursts and core-collapse supernova host galaxies. We also present our follow-up of DESI-selected candidate host galaxies using the Fraunhofer Telescope at the Wendelstein Observatory, and show the promise of DESI for associating or rejecting candidate electromagnetic counterparts to gravitational-wave alerts. These results emphasize the value of DESI’s extensive spectroscopic dataset in rapidly characterizing host galaxies, enabling spectroscopic host subtraction, and guiding targeted follow-up.

  PublisherDOI

• The Lazuli Space Observatory: Architecture &amp; Capabilities

  arXiv (Cornell University) · 2026-01-05

  preprintOpen access

  The Lazuli Space Observatory is a 3-meter aperture astronomical facility designed for rapid-response observations and precision astrophysics across visible to near-infrared wavelengths (400-1700 nm bandpass). An off-axis, freeform telescope delivers diffraction-limited image quality (Strehl $&gt;$0.8 at 633 nm) to three instruments across a wide, flat focal plane. The three instruments provide complementary capabilities: a Wide-field Context Camera (WCC) delivers multi-band imaging over a 35' $\times$ 12' footprint with high-cadence photometry; an Integral Field Spectrograph (IFS) provides continuous 400-1700 nm spectroscopy at R $\sim$ 100-500 for stable spectrophotometry; and an ExtraSolar Coronagraph (ESC) enables high-contrast imaging expected to reach raw contrasts of $10^{-8}$ and post-processed contrasts approaching $10^{-9}$. Operating from a 3:1 lunar-resonant orbit, Lazuli will respond to targets of opportunity in under four hours--a programmatic requirement designed to enable routine temporal responsiveness that is unprecedented for a space telescope of this size. Lazuli's technical capabilities are shaped around three broad science areas: (1) time-domain and multi-messenger astronomy, (2) stars and planets, and (3) cosmology. These capabilities enable a potent mix of science spanning gravitational wave counterpart characterization, fast-evolving transients, Type Ia supernova cosmology, high-contrast exoplanet imaging, and spectroscopy of exoplanet atmospheres. While these areas guide the observatory design, Lazuli is conceived as a general-purpose facility capable of supporting a wide range of astrophysical investigations, with open time for the global community. We describe the observatory architecture and capabilities in the preliminary design phase, with science operations anticipated following a rapid development cycle from concept to launch.

  PublisherDOI

• Dark Energy Survey Year 6 Results: MagLim++ Lens Sample Selection and Measurements of Galaxy Clustering

  HAL (Le Centre pour la Communication Scientifique Directe) · 2026-01-20

  preprintOpen access

  Galaxy clustering is a sensitive probe of the expansion history and growth of structure of the universe, and key degeneracies can be broken by combining these data with measurements of cosmic shear and galaxy-galaxy lensing (a so-called 3$\times$2pt analysis). The largest and least biased statistical samples of galaxies for use in clustering analyses can be collected photometrically through large imaging surveys. However, selecting clean photometric subsamples for cosmology are crucial for avoiding contamination that can bias cosmological constraints. Here we present the MagLim++ galaxy sample, selected to optimize for cosmological constraining power and incorporating an array of novel quality cuts to identify and remove residual contamination. This sample comes from the full six years of observations from the Dark Energy Survey. We present measurements of the two-point angular clustering ($w(θ)$) of 9,186,205 galaxies distributed over 4031 sq. degrees and in six tomographic redshift bins centered at $\bar{z}\approx$ [0.31, 0.44, 0.62, 0.78, 0.90, 1.01]. These measurements are used as part of the 3$\times$2pt and other DES Y6 legacy cosmological analyses in companion works. We describe the battery of null tests and mitigation schemes implemented to address observational, astrophysical, and methodological systematics in the analysis. The resulting $w(θ)$ measurements have a S/N = 149 (90.2 for linear scales only), which we use to place galaxy-clustering-only constraints on the matter density of the Universe, $Ω_m=0.311^{+0.023}_{-0.035}$, and amplitude of galaxy clustering in each redshift bin, $b_iσ_8=[1.16^{+0.04}_{-0.06},\ 1.40^{+0.04}_{-0.06},\ 1.57^{+0.04}_{-0.06},\ 1.59^{+0.04}_{-0.05},\ 1.50^{+0.04}_{-0.05},\ 1.74^{+0.06}_{-0.08}]$.

  PublisherOA PDFDOI

• The DESI Transients Survey: Legacy Classifications and Methodology

  Zenodo (CERN European Organization for Nuclear Research) · 2026-01-13

  articleOpen access

  Supplementary material to DESI's publication The DESI Transients Survey: Legacy Classifications and Methodology to comply with the data management plan. Here we provide the spectroscopic data used for classifications and the DESI spectra that resulted from our crossmatching of TNS and DESI.

  PublisherDOI

• Probing the Environment around GW170817 with DESI: Insights on Galaxy Group Peculiar Velocities for Standard Siren Measurements

  The Astrophysical Journal · 2026-04-14

  preprintOpen access

  Abstract We present a new measurement of the Hubble constant, H 0 , following the gravitational-wave event GW170817 and Dark Energy Spectroscopic Instrument (DESI) observations. A standard siren measurement with a nearby (luminosity distance ∼40 Mpc) event such as GW170817 is typically sensitive to the peculiar motion of the host galaxy owing to local dynamics. Previous measurements from this event have taken advantage of peculiar velocity measurements of nearby galaxies, including a handful of objects in the galaxy group that the host of the event, NGC 4993, has been associated with. Still, the group’s properties and NGC 4993’s membership were debated. We present DESI observations of thousands of galaxies in the vicinity of NGC 4993, resulting in 39 group galaxies and a fivefold increase in galaxies compared to previous observations, with many contributing to a peculiar velocity measurement. Examining the local dynamics, our observations support the presence of a galaxy group of which NGC 4993 is a part with a halo mass of order ∼10 13 M ⊙ . Using peculiar velocity measurements from our fundamental plane galaxy observations, we find <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>70</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>8.5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>6.4</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> km s −1 Mpc −1 . In addition, using a peculiar velocity measurement for NGC 4993 from surface brightness fluctuations in Cosmicflows-4, we find <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:msub> <mml:mrow> <mml:mi>H</mml:mi> </mml:mrow> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>73</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>3.9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>3.3</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> km s −1 Mpc −1 . We study the impact of different galaxy selection criteria on the determination of the peculiar velocity and, in turn, on the H 0 measurement. Our results demonstrate the value of multiplexed spectroscopic observations for probing the local environments of gravitational-wave events used in standard siren measurements.

  PublisherDOI

• Dark Energy Survey: Implications for cosmological expansion models from the final DES baryon acoustic oscillation and supernova data

  Physical review. D/Physical review. D. · 2026-01-30 · 6 citations

  article

  International audience

  PublisherDOI

• The Lazuli Space Observatory: Architecture & Capabilities

  ArXiv.org · 2026-01-05

  articleOpen access

  International audience

  PublisherOA PDF

Recent grants

• Probing the Universe's expansion and gravitational wave sources with ground-based optical telescopes

  NSF · $466k · 2023–2026

Frequent coauthors

• L. N. da Costa

  Laboratório Interinstitucional de e-Astronomia

  833 shared

• E. Bertin

  Orange (France)

  768 shared

• D. Gruen

  765 shared

• K. Kuehn

  Netherlands Institute for Radio Astronomy

  740 shared

• A. Carnero Rosell

  688 shared

• J. Gschwend

  Laboratório Interinstitucional de e-Astronomia

  644 shared

• M. Costanzi

  Institute for Fundamental Physics of the Universe

  643 shared

• M. Carrasco Kind

  Urbana University

  609 shared

Labs

• Antonella Palmese Research GroupPI

Education

• Ph.D.

  University College London

  2018

• M.S.

  La Sapienza University of Rome

  2013

• B.S.

  La Sapienza University of Rome

  2011

Awards & honors

• Leonardo Da Vinci Award for Physics, Math, and Engineering (…
• Einstein Fellowship (2021)
• Fermilab Exceptional Performance Recognition Award (2020)
• Royal Astronomical Society Michael Penston Prize runner-up (…
• Enrico Persico award (2014)