AI 中文总结
研究系外黄道光对系外类地行星特征表征的影响，通过模拟不同密度和成分的系外类地行星系统及应用大气反演工具于合成光谱，发现其会使光谱特征表观深度降低，还给出了去除影响的方法及对相关研究的重要性。
AI 中文摘要
所有系外行星系统都预计存在源自小行星的系外黄道尘埃（exozodi）。对于许多恒星而言，exozodi很可能是直接观测系外类地行星时天体物理噪声的最大来源。附近类似太阳的系统可能比我们的太阳系有至少3倍多的宜居带（HZ）尘埃，必须从直接图像和光谱中去除这些尘埃才能揭示系外行星信号。这种微米级尘埃的反照率在可见光到近红外波长范围内平滑变化，但exozodi可能由不同物质组成，会影响其颜色。若不减去，系外黄道光会给提取的光谱增加类似云的连续发射，可能通过降低光谱特征的表观吸收深度使表征研究产生偏差。为量化这些影响，我们模拟了一系列exozodi密度和成分的系外类地行星系统，并将大气反演工具应用于合成的宜居世界天文台（HWO）光谱。我们发现，与太阳系水平相当（即1个zodi）的exozodi可使可见波长分子吸收特征的表观深度降低多达50%，且在更长波长下这种效应更严重。为测量分子丰度，可能需要大量后处理将exozodi去除到分数残余，残余会随尘埃密度而收紧。然而，针对吸收物种的二元检测结果可将此要求放宽一个数量级，尤其是在更高光谱分辨率下。了解并减轻exozodi对提取的系外类地行星光谱的影响，对于用HWO表征HZ系外行星环境并最终寻找宜居性和生命迹象至关重要。
英文摘要
All exoplanetary systems are expected to host exozodiacal dust, or exozodi, originating from planetesimals. For many stars, exozodi will likely be the largest source of astrophysical noise in direct observations of terrestrial exoplanets. Nearby Sun-like systems likely have $\gtrsim3$x more habitable zone (HZ) dust than our solar system, which must be removed from direct images and spectra to reveal exoplanet signals. The albedo of this micron-sized dust varies smoothly over VIS -- NIR wavelengths, but exozodi can be composed of different materials that can impact its color. If left unsubtracted, exozodiacal light will add cloud-like continuum emission to extracted spectra, potentially biasing characterization studies by reducing the apparent absorption depth of spectral features. To quantify these effects, we simulate exoEarth systems with a range of exozodi densities and compositions, and apply an atmospheric retrieval tool to synthetic Habitable Worlds Observatory (HWO) spectra. We find that exozodi at levels similar to the solar system (i.e., 1 zodi) can reduce the apparent depth of visible wavelength molecular absorption features by up to 50\%, an effect that worsens at longer wavelengths. To measure molecular abundances, significant post-processing may be required to remove exozodi to a fractional residual that tightens with dust density. However, targeting a binary detection result for an absorbing species instead relaxes this requirement by an order of magnitude, especially at higher spectral resolution. Understanding and mitigating the effects of exozodi in extracted exoEarth spectra is critical to characterize HZ exoplanet environments with HWO and ultimately to search for signs of habitability and life.
CommentsAccepted to AJ; 15 pages, 10 figures
