论文标题
在红移Z处微弱的星形星系中的Lyman Continuum泄漏
Lyman continuum leakage in faint star-forming galaxies at redshift z=3-3.5 probed by gamma-ray bursts
论文作者
论文摘要
我们介绍了Grb 191004b $ z = 3.5055 $的Lyman Continuum（LYC）排放的观察结果，以及其他两个先前已知的Lyc发射长伽马射线爆发（lgrb）（lgrb）（grb 050908）（$ z = 3.3467 $ z = 3.3467 $ z = 3.3467 $ z = 3.0606060606060607a at分数并比较其属性。从GRB 191004B的余波光谱中，我们在$ \ log（n _ {\ rm hi}/cm^{ - 2}）= 17.2 \ pm 0.15 $的lgrb红移（n _ {\ rm hi}/cm^{ - 2}）处确定中性氢柱密度。检测到的唯一金属吸收系是CIV和SIIV。与GRB 050908和GRB 060607A相反，GRB 191004b的主机银河显示出明显的$ ly $α$排放。从其$α$排放和Balmer发射线的非检测中，我们将其星形形态率（SFR）限制为$ 1 \ leq $ sfr $ \ leq 4.7 $ m $ m $ _ {\ odot} \ yr^{ - 1} $。我们使用壳模型拟合$α$发射，并找到与观察到的参数值。我们找到了GRB 191004b，GRB 050908和GRB 060607A的绝对LYC逃生分数，为$ 0.35^{+0.10} _ { - 0.11} $，$ 0.08^{+0.05} {+0.05} _ { - 0.04} $ { - 0.04} $和0.20^$ 0.20^$ 0.20^$ 0.05} $ 0.05} $} - 0.05} - 0.05。我们将LGRB的LYC逃生分数与从文献中发现的其他LYC发射器的值进行了比较，这表明LGRB余气可能是研究LYC逃生的强大工具，用于微弱的高红色星形形成星系。确实，我们可以将LYC泄漏研究推向更高的绝对幅度。此处介绍的三个LGRB的主机星系都有所有$ M _ {\ rm 1600}> -19.5 $ mag，grb 060607a主机在$ m _ {\ rm 1600}> -16 $ mag。因此，LGRB宿主可能特别适合探索对于传统技术太微弱或遥远的星系中的电离逃生部分。此外，与星系研究相比，时间投资非常小。 [简略]
We present the observations of Lyman continuum (LyC) emission in the afterglow spectra of GRB 191004B at $z=3.5055$, together with those of the other two previously known LyC-emitting long gamma-ray bursts (LGRB) (GRB 050908 at $z=3.3467$, and GRB 060607A at $z=3.0749$), to determine their LyC escape fraction and compare their properties. From the afterglow spectrum of GRB 191004B we determine a neutral hydrogen column density at the LGRB redshift of $\log(N_{\rm HI}/cm^{-2})= 17.2 \pm 0.15$, and negligible extinction ($A_{\rm V}=0.03 \pm 0.02$ mag). The only metal absorption lines detected are CIV and SiIV. In contrast to GRB 050908 and GRB 060607A, the host galaxy of GRB 191004B displays significant Ly$α$ emission. From its Ly$α$ emission and the non-detection of Balmer emission lines we constrain its star-formation rate (SFR) to $1 \leq$ SFR $\leq 4.7$ M$_{\odot}\ yr^{-1}$. We fit the Ly$α$ emission with a shell model and find parameters values consistent with the observed ones. The absolute LyC escape fractions we find for GRB 191004B, GRB 050908 and GRB 060607A are of $0.35^{+0.10}_{-0.11}$, $0.08^{+0.05}_{-0.04}$ and $0.20^{+0.05}_{-0.05}$, respectively. We compare the LyC escape fraction of LGRBs to the values of other LyC emitters found from the literature, showing that LGRB afterglows can be powerful tools to study LyC escape for faint high-redshift star-forming galaxies. Indeed we could push LyC leakage studies to much higher absolute magnitudes. The host galaxies of the three LGRB presented here have all $M_{\rm 1600} > -19.5$ mag, with the GRB 060607A host at $M_{\rm 1600} > -16$ mag. LGRB hosts may therefore be particularly suitable for exploring the ionizing escape fraction in galaxies that are too faint or distant for conventional techniques. Furthermore the time investment is very small compared to galaxy studies. [Abridged]
