Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction

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Main Authors: Arendse, Nikki, Mörtsell, Edvard, Weisenbach, Luke, Hayes, Erin, Thorp, Stephen, Dhawan, Suhail, Goobar, Ariel, Guerrini, Sacha, Hjortlund, Jacob Osman, Johansson, Joel, Lemon, Cameron, Zaif, Abdullah Al
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Published: 2025
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author Arendse, Nikki
Mörtsell, Edvard
Weisenbach, Luke
Hayes, Erin
Thorp, Stephen
Dhawan, Suhail
Goobar, Ariel
Guerrini, Sacha
Hjortlund, Jacob Osman
Johansson, Joel
Lemon, Cameron
Zaif, Abdullah Al
author_facet Arendse, Nikki
Mörtsell, Edvard
Weisenbach, Luke
Hayes, Erin
Thorp, Stephen
Dhawan, Suhail
Goobar, Ariel
Guerrini, Sacha
Hjortlund, Jacob Osman
Johansson, Joel
Lemon, Cameron
Zaif, Abdullah Al
contents To date, only two strongly lensed type Ia supernovae (SNIa) have been discovered with an isolated galaxy acting as the lens: iPTF16geu and SN Zwicky. The observed image fluxes for both lens systems were inconsistent with predictions from a smooth macro lens model. A potential explanation for the anomalous flux ratios is microlensing: additional (de)magnification caused by stars and other compact objects in the lens galaxy. In this work, we combine observations of iPTF16geu and SN Zwicky with simulated microlensing magnification maps, leveraging their standardizable candle properties to constrain the lens galaxy mass slope, $η$, and the fraction of dark compact objects, $f_{\rm dc}$. The resulting mass slopes are $η= 1.70 \pm 0.07$ for iPTF16geu and $η= 1.81 \pm 0.10$ for SN Zwicky. Our results indicate no evidence for a population of dark compact objects, placing upper limits at the $95\%$ confidence level of $f_{\rm dc} < 0.25$ for iPTF16geu and $f_{\rm dc} < 0.47$ for SN Zwicky (for compact objects with masses above $ 0.02 M_{\odot}$). Assuming a constant fraction of dark compact objects for both lensed SNe, we obtain $f_{\rm dc} < 0.19$. These results highlight the potential of strongly lensed SNIa to probe the innermost parts of lens galaxies and learn about compact matter.
format Preprint
id arxiv_https___arxiv_org_abs_2501_01578
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction
Arendse, Nikki
Mörtsell, Edvard
Weisenbach, Luke
Hayes, Erin
Thorp, Stephen
Dhawan, Suhail
Goobar, Ariel
Guerrini, Sacha
Hjortlund, Jacob Osman
Johansson, Joel
Lemon, Cameron
Zaif, Abdullah Al
Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
To date, only two strongly lensed type Ia supernovae (SNIa) have been discovered with an isolated galaxy acting as the lens: iPTF16geu and SN Zwicky. The observed image fluxes for both lens systems were inconsistent with predictions from a smooth macro lens model. A potential explanation for the anomalous flux ratios is microlensing: additional (de)magnification caused by stars and other compact objects in the lens galaxy. In this work, we combine observations of iPTF16geu and SN Zwicky with simulated microlensing magnification maps, leveraging their standardizable candle properties to constrain the lens galaxy mass slope, $η$, and the fraction of dark compact objects, $f_{\rm dc}$. The resulting mass slopes are $η= 1.70 \pm 0.07$ for iPTF16geu and $η= 1.81 \pm 0.10$ for SN Zwicky. Our results indicate no evidence for a population of dark compact objects, placing upper limits at the $95\%$ confidence level of $f_{\rm dc} < 0.25$ for iPTF16geu and $f_{\rm dc} < 0.47$ for SN Zwicky (for compact objects with masses above $ 0.02 M_{\odot}$). Assuming a constant fraction of dark compact objects for both lensed SNe, we obtain $f_{\rm dc} < 0.19$. These results highlight the potential of strongly lensed SNIa to probe the innermost parts of lens galaxies and learn about compact matter.
title Microlensing of lensed supernovae Zwicky & iPTF16geu: constraints on the lens galaxy mass slope and dark compact object fraction
topic Astrophysics of Galaxies
Cosmology and Nongalactic Astrophysics
url https://arxiv.org/abs/2501.01578