update

Author: AstroJacobLi

_data/menu.yml

@@ -7,8 +7,6 @@
 - title: "Research"
   href: "/research/"
   subcategories:
-    - subtitle: "Dwarf Planet"
-      subhref: "/research/TNO"
     - subtitle: "Ultra-Puffy Galaxies"
       subhref: "/research/BeyondUDG"
     - subtitle: "Isolated Quiescent Dwarf"

about.md

@@ -7,26 +7,26 @@ permalink: /about/
 <p>I am Jiaxuan Li 李嘉轩 (pronounced as <a href="https://translate.google.com/#view=home&op=translate&sl=zh-CN&tl=zh-CN&text=李嘉轩"><strong>Lǐ Jiā Xuān</strong> </a>), a graduate student at <a class="princeton_style" href="https://web.astro.princeton.edu">Department of Astrophysical Sciences, Princeton University</a>.
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 <br> 
-I'm an observer interested in a variety of topics in astronomy and astrophysics, such as galaxy formation and evolution, low surface brightness astrophysics, sky surveys, machine learning, and instrumentation. My current research primarily involves uncovering the formation and evolution of dwarf galaxies through both exquisite observations and numerical simulations. 
+I'm an observer interested in a variety of topics in astronomy and astrophysics, such as galaxy formation and evolution, low surface brightness astrophysics, sky surveys, machine learning, and instrumentation. My current research primarily involves uncovering the formation and evolution of dwarf galaxies through both exquisite observations and numerical simulations. Recently I've also been interested in solar system objects, especially trans-Neptunian objects and Planet 9. Check out my <a href="https://astrojacobli.github.io/research/">Research</a> page for more details.
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-
-I have been actively engaging with data from cutting-edge deep sky surveys such as the <a href="https://hsc.mtk.nao.ac.jp">Hyper Suprime-Camera (HSC) Subaru Strategic Program (SSP)</a>. With my advisor <a href="https://web.astro.princeton.edu/people/jenny-greene">Jenny Greene</a> and her team at Princeton, we systematically studied the <b>Ultra-Puffy Galaxies™</b> around galaxies similar to our Milky Way. These puffy galaxies are defined to be 1.5-sigma above the average mass-size relation. Compared with the commonly-used Ultra-Diffuse Galaxy concept, our definition for ultra-puffy galaxies, based on the mass-size relation, better represent the tail of the satellite size distribution. Surprisingly, the quenched fraction (the fraction of galaxies that are quiescent in star formation) of these ultra-puffy galaxies is very similar to normal-sized satellites of Milky Way-analogs, implying that <b>quenching is not tied to being a mass-size outlier</b>. These results will shed light on the formation and evolution mechanism of puffy satellites, and challenge the current theoretical models. Please check out <a href="https://arxiv.org/abs/2210.14994">Li et al. (2023a)</a> and <a href="https://arxiv.org/abs/2302.14108">Li et al. (2023b)</a> for details.
-<br>
-<br>
-
-Recently, I am keen on harnessing advanced machine learning techniques to address astrophysical challenges. With <a href="https://pmelchior.net/">Peter Melchior</a>, <a href="https://dr-guangtou.github.io/">Song Huang</a>, <a href="https://changhoonhahn.github.io/">ChangHoon Hahn</a>, we developed a novel framework, <b>"PopSED"</b>, for population-level inference of galaxy properties from photometric data. Unlike the traditional approach of first analyzing individual galaxies and then combining the results to determine the physical properties of the entire galaxy population, we directly make the population distribution the inference objective. PopSED reliably recovers the redshift and stellar mass distribution of 100K galaxies using broadband photometry within 1 GPU-hour, being <b>1 million times faster</b> than the traditional SED modeling method. With the unprecedented number of galaxies in upcoming surveys, our method offers an efficient tool for studying galaxy evolution and deriving redshift distributions for cosmological analyses. Check out our paper <a href="https://ui.adsabs.harvard.edu/abs/2023arXiv230916958L/abstract">here</a>!
+<!-- 
+I have been actively engaging with data from cutting-edge deep sky surveys such as the <a href="https://hsc.mtk.nao.ac.jp">Hyper Suprime-Camera (HSC) Subaru Strategic Program (SSP)</a>. With my advisor <a href="https://web.astro.princeton.edu/people/jenny-greene">Jenny Greene</a> and her team at Princeton, we systematically studied the <b>Ultra-Puffy Galaxies™</b> around galaxies similar to our Milky Way. These puffy galaxies are defined to be 1.5-sigma above the average mass-size relation. Compared with the commonly-used Ultra-Diffuse Galaxy concept, our definition for ultra-puffy galaxies, based on the mass-size relation, better represent the tail of the satellite size distribution. Surprisingly, the quenched fraction (the fraction of galaxies that are quiescent in star formation) of these ultra-puffy galaxies is very similar to normal-sized satellites of Milky Way-analogs, implying that <b>quenching is not tied to being a mass-size outlier</b>. These results will shed light on the formation and evolution mechanism of puffy satellites, and challenge the current theoretical models. Please check out <a href="https://arxiv.org/abs/2210.14994">Li et al. (2023a)</a> and <a href="https://arxiv.org/abs/2302.14108">Li et al. (2023b)</a> for details. -->
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-
-I worked on <a href="https://hsc.mtk.nao.ac.jp">Hyper Suprime-Camera (HSC)</a> data to study the stellar halo of massive galaxies. Together with <a href="https://alexie.sites.ucsc.edu/">Alexie Leauthaud</a>, <a href="http://dr-guangtou.github.io/">Song Huang</a>, <a href="https://moustakas.siena.edu/">John Moustakas</a> and the [Dragonfly](http://dragonflytelescope.org/) team, we explored the ability of different sky surveys (HSC, DECaLS, Dragonfly and SDSS) to extract the stellar halo light profiles of massive galaxies. We effectively addressed the major systematic error (sky background subtraction) in measuring the surface brightness profiles. We push the detection limit of HSC to 30 mag per square arcsec in r-band and find good agreement between DECaLS and HSC measurements (less than 0.05 dex difference on stellar mass measurements). Check out our paper: <a href="https://arxiv.org/abs/2111.03557">Reaching for the Edge I: Probing the Outskirts of Massive Galaxies with HSC, DECaLS, SDSS, and Dragonfly</a>.
+<!-- 
+Recently, I am keen on harnessing advanced machine learning techniques to address astrophysical challenges. With <a href="https://pmelchior.net/">Peter Melchior</a>, <a href="https://dr-guangtou.github.io/">Song Huang</a>, <a href="https://changhoonhahn.github.io/">ChangHoon Hahn</a>, we developed a novel framework, <b>"PopSED"</b>, for population-level inference of galaxy properties from photometric data. Unlike the traditional approach of first analyzing individual galaxies and then combining the results to determine the physical properties of the entire galaxy population, we directly make the population distribution the inference objective. PopSED reliably recovers the redshift and stellar mass distribution of 100K galaxies using broadband photometry within 1 GPU-hour, being <b>1 million times faster</b> than the traditional SED modeling method. With the unprecedented number of galaxies in upcoming surveys, our method offers an efficient tool for studying galaxy evolution and deriving redshift distributions for cosmological analyses. Check out our paper <a href="https://ui.adsabs.harvard.edu/abs/2023arXiv230916958L/abstract">here</a>! -->
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-I helped <a href="https://www.pietervandokkum.com/">Prof. Pieter van Dokkum</a> (Yale) on developing and maintaining the <a href="https://github.com/AstroJacobLi/mrf">"Multi-resolution filtering (MRF)"</a> technique (<a href="https://ui.adsabs.harvard.edu/abs/2019arXiv191012867V/abstract">van Dokkum et al. 2019</a>), which is designed to isolate extended low surface brightness emissions in the <a href="http://dragonflytelescope.org">Dragonfly</a> imaging data. Using this technique, we are aiming to discover unseen low surface brightness objects including ultra-diffuse galaxies, tidal disruption debris and Galactic cirrus in the Dragonfly Wide Field Survey. I'm also working on the Dragonfly images of NGC 1052 field to constrain the total mass of <a href="https://ui.adsabs.harvard.edu/abs/2018Natur.555..629V/abstract">NGC1052-DF2</a> and <a href="https://ui.adsabs.harvard.edu/abs/2019ApJ...874L...5V/abstract">DF4</a>, which are believed to be lacking dark matter.
+<!-- 
+I worked on <a href="https://hsc.mtk.nao.ac.jp">Hyper Suprime-Camera (HSC)</a> data to study the stellar halo of massive galaxies. Together with <a href="https://alexie.sites.ucsc.edu/">Alexie Leauthaud</a>, <a href="http://dr-guangtou.github.io/">Song Huang</a>, <a href="https://moustakas.siena.edu/">John Moustakas</a> and the [Dragonfly](http://dragonflytelescope.org/) team, we explored the ability of different sky surveys (HSC, DECaLS, Dragonfly and SDSS) to extract the stellar halo light profiles of massive galaxies. We effectively addressed the major systematic error (sky background subtraction) in measuring the surface brightness profiles. We push the detection limit of HSC to 30 mag per square arcsec in r-band and find good agreement between DECaLS and HSC measurements (less than 0.05 dex difference on stellar mass measurements). Check out our paper: <a href="https://arxiv.org/abs/2111.03557">Reaching for the Edge I: Probing the Outskirts of Massive Galaxies with HSC, DECaLS, SDSS, and Dragonfly</a>. -->
 <br>
+<!-- <br>
+I helped <a href="https://www.pietervandokkum.com/">Prof. Pieter van Dokkum</a> (Yale) on developing and maintaining the <a href="https://github.com/AstroJacobLi/mrf">"Multi-resolution filtering (MRF)"</a> technique (<a href="https://ui.adsabs.harvard.edu/abs/2019arXiv191012867V/abstract">van Dokkum et al. 2019</a>), which is designed to isolate extended low surface brightness emissions in the <a href="http://dragonflytelescope.org">Dragonfly</a> imaging data. Using this technique, we are aiming to discover unseen low surface brightness objects including ultra-diffuse galaxies, tidal disruption debris and Galactic cirrus in the Dragonfly Wide Field Survey. I'm also working on the Dragonfly images of NGC 1052 field to constrain the total mass of <a href="https://ui.adsabs.harvard.edu/abs/2018Natur.555..629V/abstract">NGC1052-DF2</a> and <a href="https://ui.adsabs.harvard.edu/abs/2019ApJ...874L...5V/abstract">DF4</a>, which are believed to be lacking dark matter. -->
+<!-- <br>
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 Advised by <a href="http://kiaa.pku.edu.cn/people/yingjie-peng">Prof. Yingjie Peng</a> (KIAA), I utilized <a href="https://www.sdss.org/dr14/manga/">MaNGA IFU</a> data and discovered a population of galaxies which have H-alpha ring-like emission structures. We studied their properties and found high bar fraction, high AGN (Seyfert & LINER) fraction and high bulge-to-total ratio. This might support that it is the joint effect of bar, bulge and AGN that quenches the spiral galaxies in an inside-out mode. 
-<br>
+<br> -->
 
 <!--
 Except for observations, I'm looking forward to working on some theoretical problems. In the first two years of college, I was fascinated by statistical mechanics and non-linear physics. I studied Faraday pattern on the surface of non-newton fluid using a novel data processing approach. More details can be found on <a href="https://astrojacobli.github.io/research/"><strong>Research</strong> </a>. -->

index.html

@@ -12,9 +12,15 @@
 <p>I am Jiaxuan Li 李嘉轩 (pronounced as <a href="https://translate.google.com/#view=home&op=translate&sl=zh-CN&tl=zh-CN&text=李嘉轩"><strong>Lǐ Jiā Xuān</strong> </a>), a graduate student at <a class="princeton_style" href="https://web.astro.princeton.edu">Department of Astrophysical Sciences, Princeton University</a>.
 <br>
 <br> 
-I'm an observer interested in a variety of topics in astronomy and astrophysics, such as galaxy formation and evolution, low surface brightness astrophysics, sky surveys, machine learning, and instrumentation. My current research primarily involves uncovering the formation and evolution of dwarf galaxies through both exquisite observations and numerical simulations. I have been actively engaging with data from cutting-edge deep sky surveys such as the <a href="https://hsc.mtk.nao.ac.jp">Hyper Suprime-Camera (HSC) Subaru Strategic Program (SSP)</a> and the <a href="https://merian.sites.ucsc.edu/">Merian Survey</a>. Additionally, I am keen on harnessing advanced machine learning techniques to address astrophysical challenges. For more information, please visit my <a href="https://astrojacobli.github.io//research/"><strong>Research</strong></a> page.
+I'm an observer interested in a variety of topics in astronomy and astrophysics, mainly on galaxy formation and evolution, low surface brightness astrophysics, sky surveys, machine learning, and instrumentation. My current research primarily involves uncovering the formation and evolution of dwarf galaxies through both exquisite observations and numerical simulations. I have been actively engaging with data from cutting-edge deep sky surveys such as the <a href="https://hsc.mtk.nao.ac.jp">Hyper Suprime-Camera (HSC) Subaru Strategic Program (SSP)</a> and the <a href="https://merian.sites.ucsc.edu/">Merian Survey</a>. Additionally, I am keen on harnessing advanced machine learning techniques to address astrophysical challenges. For more information, please visit my <a href="https://astrojacobli.github.io//research/"><strong>Research</strong></a> page.
+
+<br>
+
+Recently, together with <a href="https://sihaocheng.github.io/">Sihao Cheng</a> (IAS) and <a href="https://web.astro.princeton.edu/people/eritas-yang">Eritas Yang</a> (Princeton), we discovered an exceptional trans-Neptunian object (TNO) [2017 OF201](https://en.wikipedia.org/wiki/2017_OF201). The most striking feature of 2017 OF201 is that its orbit does not following the apsidal clustering pattern observed in many other extreme TNOs. This pattern is thought to be caused by the gravitational influence of a massive planet beyond Neptune, or so-called [Planet 9 or Planet X](https://en.wikipedia.org/wiki/Planet_Nine). The existence of 2017 OF201 might suggest that Planet 9 or X doesn't exist. Check out our <a href="https://ui.adsabs.harvard.edu/abs/2025arXiv250515806C/abstract">paper</a> for more details. This work was featured in the <a href="https://www.ias.edu/news/extreme-cousin-pluto-possible-dwarf-planet-discovered-solar-systems-edge">IAS</a> and <a href="https://web.astro.princeton.edu/news/princeton-astronomers-discover-extraordinary-distant-object-solar-systems-edge">Princeton University</a> websites, as well as in <a href="https://phys.org/news/2025-05-extreme-cousin-pluto-dwarf-planet.html">Phys.org</a>, <a href="https://www.newscientist.com/article/2481477-new-dwarf-planet-spotted-at-the-edge-of-the-solar-system/">New Scientist</a>, <a href="https://www.universetoday.com/articles/our-solar-system-may-have-a-new-planetary-sibling-another-dwarf-planet">Universe Today</a>, <a href="https://earthsky.org/space/new-minor-planet-found-in-the-distant-solar-system-2017-of201/">EarthSky</a>.
 <br>
 <br>
+<br>
+
 Originally from <a href="https://zh.wikipedia.org/wiki/定西市">Dingxi</a>, Gansu Province, a small town in northwestern China, I became an amateur astronomer since I was in sixth grade in primary school. My enthusiasm led me to participate in the Chinese National Astronomy Olympiad and several international competitions. Prior to my journey at Princeton, I completed my undergraduate studies in Astrophysics at <a href="https://www.pku.edu.cn">Peking University</a>. Outside of my academic endeavors, I engage in photography, capturing diverse subjects from celestial bodies to daily life scenes. I also enjoy drinking. 
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research.md

@@ -19,12 +19,9 @@ Led by my longtime friend [Sihao Cheng](https://sihaocheng.github.io/) (IAS), to
 
 With these detections spanning over 7 years, we were able to trace the object's orbit to a very good precision. This object is in an extremely wide (a ~ 840 au) and eccentric (e ~ 0.946) orbit that takes approximately 25,000 years to complete. At a distance of ~90 au from the Sun now, it has a diameter of about 700 km, assuming an albedo of 0.15. It is potentially large enough to qualify as a dwarf planet like Pluto. 
 
-<br>
 
 {% include image.html url="/images/TNO/orbits_press_release.jpeg" caption="Image showing the orbits and the current location of Pluto, Neptune, and 2017 OF201. <br>Figure credit: Jiaxuan Li (Princeton), Sihao Cheng (IAS)" width=650 align="center" %}
 
-<br>
-
 
 The most striking feature of 2017 OF201 is that its orbit does not following the apsidal clustering pattern observed in many other extreme TNOs (see the figure on the right). This pattern is thought to be caused by the gravitational influence of a massive planet beyond Neptune, or so-called [Planet 9 or Planet X](https://en.wikipedia.org/wiki/Planet_Nine). However, 2017 OF201's orbit is not aligned with this clustering, suggesting that it may have been perturbed by a different mechanism, or it implies that Planet 9/X doesn't exist. 
 
@@ -34,6 +31,8 @@ Because of its extreme orbit, 2017 OF201 can be detected by surveys with similar
 
 
 
+<br>
+
 
 ### ELVES-Dwarf Survey: Probing Satellites of Isolated Dwarf Galaxies in the Local Volume