Very recent gamma-ray observations of G120.1+1.4 (Tycho's) supernova remnant (SNR) by Fermi-LAT and VERITAS provided new fundamental pieces of information for understanding particle acceleration and non-thermal emission in SNRs. We want to outline a coherent description of Tycho's properties in terms of SNR evolution, shock hydrodynamics and multi-wavelength emission by accounting for particle acceleration at the forward shock via first order Fermi mechanism. We adopt here a quick and reliable semi-analytical approach to non-linear diffusive shock acceleration which includes magnetic field amplification due to resonant streaming instability and the dynamical backreaction on the shock of both cosmic rays (CRs) and self-generated magnetic turbulence. We find that Tycho's forward shock is accelerating protons up to at least 500 TeV, channelling into CRs about the 10 per cent of its kinetic energy. Moreover, the CR-induced streaming instability is consistent with all the observational evidences indicating a very efficient magnetic field amplification (up to ~300 micro Gauss). In such a strong magnetic field the velocity of the Alfvén waves scattering CRs in the upstream is expected to be enhanced and to make accelerated particles feel an effective compression factor lower than 4, in turn leading to an energy spectrum steeper than the standard prediction {\propto} E^-2. This latter effect is crucial to explain the GeV-to-TeV gamma-ray spectrum as due to the decay of neutral pions produced in nuclear collisions between accelerated nuclei and the background gas. The self-consistency of such an hadronic scenario, along with the fact that the concurrent leptonic mechanism cannot reproduce both the shape and the normalization of the detected the gamma-ray emission, represents the first clear and direct radiative evidence that hadron acceleration occurs efficiently in young Galactic SNRs.
We present results from {\it XMM-Newton/RGS} observations of prominent knots in the southest portion of Tycho's supernova remnant, known to be the remnant of a Type Ia SN in 1572 C.E. By dispersing the photons from these knots out of the remnant with very little emission in front of or behind them, we obtained the nearly uncontaminated spectra of the knots. In the southernmost knot, the RGS successfully resolved numerous emission lines from Si, Ne, O He$α$ and Ly$α$, and Fe L-shell. This is the first clear detection of O lines in Tycho's SNR. Line broadening was measured to be $\sim 3$ eV for …
We report a possible $γ$-ray enhancement event detected from Tycho's supernova remnant (SNR), the outcome of a type Ia supernova explosion that occurred in year 1572. The event lasted for 1.5 years and showed a factor of 3.6 flux increase mainly in the energy range of 4--100 GeV, while notably accompanied with two 478\,GeV photons. Several young SNRs (including Tycho's SNR) were previously found to show peculiar X-ray structures with flux variations in one- or several-year timescales, such an event at $γ$-ray energies is for the first time seen. The year-long timescale of the event suggests a …
Expanding molecular bubble surrounding Tycho's supernova remnant (SN 1572) observed with IRAM 30 m telescope: evidence for a single-degenerate progenitor
Ia超新星的前身是单简并还是双简并白矮星系统一直是一个备受争议的话题。为了解决Ia型第谷超新星遗迹（SNR）SN 1572的起源，我们进行了$^{12}$ CO J=2-1映射和使用IRAM 30米望远镜对遗迹进行3毫米线测量。我们表明，第谷是包围着一个clusterous分子泡在当地的标准的$\sim 61$公里的$^{-1}$的速度为$\sim 4.5$公里的$^{-1}$，并有一个质量为$\sim 220$ M $_\odot$（在距离为2.5千秒差距）。增强的$^{12}$ CO J=2-1线发射相对于$^{12}$ CO J=1-0发射和可能的线加宽（在速度范围$-64$到$-60$ km s $^{-1}$）被发现在东北边界的SNR，在那里的壳变形和减速。这些功能，结合膨胀的分子泡和第谷之间的形态对应关系，表明SNR是与泡沫在速度范围$-66$到$-57$ km s $^{-1}$。最合理的起源膨胀的泡沫是快速流出（速度为数百公里秒$^{-1}$）驱动的WD附近，因为它吸积的物质从一个非退化的伴星。在低密度风吹气泡中，信噪比一直在扩大，冲击波刚刚到达分子腔壁。在低密度风吹气泡中，信噪比一直在扩大，冲击波刚刚到达分子腔壁。这是第一次明确检测到Ia型SNR的祖先驱动的膨胀气泡，这构成了Ia型SN的单一简并祖先的证据。
Mechanisms of particle heating are crucial to understanding the shock physics in supernova remnants (SNRs). However, there has been little information on time variabilities of thermalized particles so far. Here, we present a discovery of a gradually-brightening thermal X-ray emission found in Chandra data of Tycho's SNR obtained during 2000--2015. The emission exhibits a knot-like feature (Knot1) with a diameter of $\simeq0.04$~pc located in the northwestern limb, where we also find localized H$α$ filaments in an optical image taken with the Hubble Space Telescope in 2008. The model with the s…
In spite of their importance as standard candles in cosmology and as major major sites of nucleosynthesis in the Universe, what kinds of progenitor systems lead to type Ia supernovae (SN) remains a subject of considerable debate in the literature. This is true even for the case of Tycho's SN exploded in 1572 although it has been deeply studied both observationally and theoretically. Analyzing X-ray data of Tycho's supernova remnant (SNR) obtained with Chandra in 2003, 2007, 2009, and 2015, we discover that the expansion before 2007 was substantially faster than radio measurements reported in t…
We present our velocity measurements of 59 clumpy, metal-rich ejecta knots in the supernova remnant (SNR) of SN 1572 (Tycho). We use our 450 ks Chandra High Energy Transmission Grating Spectrometer observation to measure the Doppler shift of the He-like Si K$α$ line-center wavelength emitted from these knots to find their line-of-sight (radial) velocities ($v_r$). We find $v_r$ up to $\sim$ 5500 km s$^{-1}$, with roughly consistent speeds between blueshifted and redshifted ejecta knots. We also measure the proper motions (PMs) for our sample based on archival Chandra Advanced CCD Imaging Spect…
The Three-Dimensional Expansion of the Ejecta from Tycho's Supernova Remnant
我们提出了第一个三维测量的各种喷出物结的速度在第谷的超新星遗迹，已知导致Ia型爆炸。钱德拉X射线观测从2003年到2015年的12年基线，使我们能够测量近60个富硅喷出物的自行，给我们天空平面的速度。对于视线速度，我们使用两种不同的方法：一个非平衡电离模型适合强Si和S线在1.2 - 2.8 keV的制度，和一个适合的一系列高斯线组成。这些方法给出了一致的结果，使我们能够确定每个结的红色或蓝移。假设距离为3.5千秒差距，我们发现总速度的范围为2400至6600 km s $^{-1}$，平均值为4430 km s $^{-1}$。我们发现有几个区域的喷出物结已经超过了前激波。这些区域的自行超过6000 km s $^{-1}$。一些Ia型超新星爆炸模型预测喷出物的速度不对称。我们没有发现这样的速度不对称性在第谷，并讨论我们的研究结果，根据各种爆炸模型，有利于那些延迟爆轰模型相对激烈和对称的爆燃。最后，我们比较测量与模型的残余物的演变，包括光滑和clujeaghte喷出物配置文件，发现这两个喷出物配置文件可以容纳的意见。
Deciphering the explosion mechanism of Type-Ia SNe using their remnants I: general properties and a case study on Tycho's SNR
University of Virginia（弗吉尼亚大学）；Virginia Institute for Theoretical Astronomy, University of Virginia（弗吉尼亚大学理论天体物理研究所）；University of Pittsburgh（匹兹堡大学）；South African Astronomical Observatory（南非天文台）；University of Cape Town（开普敦大学）；NITheCS National Institute for Theoretical and Computational Sciences, South Africa（南非国家理论与计算科学研究所）
