分类： 天文学 >> 天文学 提交时间： 2023-02-19
Hanae Inami
Jason Surace
Lee Armus
Aaron S. Evans
Kirsten L. Larson
Loreto Barcos-Munoz
Sabrina Stierwalt
Joseph M. Mazzarella
George C. Privon
Yiqing Song
Sean Linden
Christopher C. Hayward
Torsten Boker
Vivian U
Thomas Bohn
Vassilis Charmandaris
Tanio Diaz-Santos
Justin H. Howell
Thomas Lai
Anne M. Medling
摘要： We have used the Mid-InfraRed Instrument (MIRI) on the James Webb Space Telescope (JWST) to obtain the first spatially resolved, mid-infrared (mid-IR) images of IIZw096, a merging luminous infrared galaxy (LIRG) at $z = 0.036$. Previous observations with the Spitzer Space Telescope suggested that the vast majority of the total IR luminosity (LIR) of the system originated from a small region outside of the two merging nuclei. New observations with JWST/MIRI now allow an accurate measurement of the location and luminosity density of the source that is responsible for the bulk of the IR emission. We estimate that 40-70% of the IR bolometric luminosity, or $3-5 \times 10^{11}\,{\rm{L_{\odot}}}$, arises from a source no larger than 175pc in radius, suggesting a luminosity density of at least $3-5 \times 10^{12} \, {\rm{L_{\odot} \, kpc^{-2}}}$. In addition, we detect 11 other star forming sources, five of which were previously unknown. The MIRI F1500W/F560W colors of most of these sources, including the source responsible for the bulk of the far-IR emission, are much redder than the nuclei of local LIRGs. These observations reveal the power of JWST to disentangle the complex regions at the hearts of merging, dusty galaxies.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Thomas Bohn
Hanae Inami
Tanio Diaz-Santos
Lee Armus
Sean T. Linden
Vivian U
Jason Surace
Kirsten L. Larson
Aaron S. Evans
Shunshi Hoshioka
Thomas Lai
Yiqing Song
Joseph M. Mazzarella
Loreto Barcos-Munoz
Vassilis Charmandaris
Justin H. Howell
Anne M. Medling
George C. Privon
Jeffrey A. Rich
Sabrina Stierwalt
摘要： We present James Webb Space Telescope (JWST) imaging of NGC 7469 with the Near-Infrared Camera (NIRCam) and the Mid-InfraRed Instrument (MIRI). NGC 7469 is a nearby, $z=0.01627$, luminous infrared galaxy (LIRG) that hosts both a Seyfert Type-1.5 nucleus and a circumnuclear starburst ring with a radius of $\sim$0.5 kpc. The new near-infrared (NIR) JWST imaging reveals 66 star-forming regions, 37 of which were not detected by HST observations. Twenty-eight of the 37 sources have very red NIR colors that indicate obscurations up to A$_{\rm{v}}\sim7$ and a contribution of at least 25$\%$ from hot dust emission to the 4.4$\mu$m band. Their NIR colors are also consistent with young ($<$5 Myr) stellar populations and more than half of them are coincident with the MIR emission peaks. These younger, dusty star-forming regions account for $\sim$6$\%$ and $\sim$17$\%$ of the total 1.5$\mu$m and 4.4$\mu$m luminosity of the starburst ring, respectively. Thanks to JWST, we find a significant number of young dusty sources that were previously unseen due to dust extinction. The newly identified 28 young sources are a significant increase compared to the number of HST-detected young sources (4-5). This makes the total percentage of the young population rise from $\sim$15$\%$ to 48$\%$. These results illustrate the effectiveness of JWST in identifying and characterizing previously hidden star formation in the densest star-forming environments around AGN.
分类： 天文学 >> 天文学 提交时间： 2023-02-19
Sean T. Linden
Aaron S. Evans
Lee Armus
Jeffrey A. Rich
Kirsten L. Larson
Thomas Lai
George C. Privon
Vivian U
Hanae Inami
Thomas Bohn
Yiqing Song
Loreto Barcos-Muñoz
Vassilis Charmandaris
Anne M. Medling
Sabrina Stierwalt
Tanio Diaz-Santos
Torsten Böker
Paul van der Werf
Susanne Aalto
Philip Appleton
摘要： We present the results of a {\it James Webb Space Telescope} NIRCam investigation into the young massive star cluster (YMC) population in the luminous infrared galaxy VV 114. We identify 374 compact YMC candidates with a $S/N \geq 3$, 5, and 5 at F150W, F200W, and F356W respectively. A direct comparison with our {\it HST} cluster catalog reveals that $\sim 20\%$ of these sources are undetected at optical wavelengths. Based on {\it yggdrasil} stellar population models, we identify 17 YMC candidates in our {\it JWST} imaging alone with F150W-F200W and F200W-F356W colors suggesting they are all very young, dusty ($A_{V} = 5 - 15$), and massive ($10^{5.8} < M_{\odot} < 10^{6.1}$). The discovery of these `hidden' sources, many of which are found in the `overlap' region between the two nuclei, quadruples the number of $t < 3$ Myr clusters, and nearly doubles the number of $t < 6$ Myr clusters detected in VV 114. Now extending the cluster age distribution ($dN/d\tau \propto \tau^{\gamma}$) to the youngest ages, we find a slope of $\gamma = -1.30 \pm 0.39$ for $10^{6} < \tau (\mathrm{yr}) < 10^{7}$, which is consistent with the previously determined value from $10^{7} < \tau (\mathrm{yr}) < 10^{8.5}$, and confirms that VV 114 has a steep age distribution slope for all massive star clusters across the entire range of cluster ages observed. Finally, the consistency between our {\it JWST}- and {\it HST}-derived age distribution slopes indicates that the balance between cluster formation and destruction has not been significantly altered in VV 114 over the last 0.5 Gyr.
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