Lyman Break Analogs: Constraints on the Formation of Extreme Starbursts at Low and High Redshift
Thiago S. Gonçalves, Roderik Overzier, Antara Basu-Zych, D. Christopher Martin
备注:
To appear in the proceedings of IAU Symposium 277, "Tracing the Ancestry of Galaxies on the Land of our Ancestors", eds. C. Carignan, K.C. Freeman, and F. Combes
Lyman Break Analogs (LBAs), characterized by high far-UV luminosities and surface brightnesses as detected by GALEX, are intensely star-forming galaxies in the low-redshift universe ($z\sim 0.2$), with star formation rates reaching up to 50 times that of the Milky Way. These objects present metallicities, morphologies and other physical properties similar to higher redshift Lyman Break Galaxies (LBGs), motivating the detailed study of LBAs as local laboratories of this high-redshift galaxy population. We present results from our recent integral-field spectroscopy survey of LBAs with Keck/OSIRIS, which shows that these galaxies have the same nebular gas kinematic properties as high-redshift LBGs. We argue that such kinematic studies alone are not an appropriate diagnostic to rule out merger events as the trigger for the observed starburst. Comparison between the kinematic analysis and morphological indices from HST imaging illustrates the difficulties of properly identifying (minor or major) merger events, with no clear correlation between the results using either of the two methods. Artificial redshifting of our data indicates that this problem becomes even worse at high redshift due to surface brightness dimming and resolution loss. Whether mergers could generate the observed kinematic properties is strongly dependent on gas fractions in these galaxies. We present preliminary results of a CARMA survey for LBAs and discuss the implications of the inferred molecular gas masses for formation models.
We discuss the possible origin of the double-peaked profiles recently observed in Lyman-Alpha Emitters (LAEs) at the epoch of reionization ($z \gtrsim 6.5$) from obscured active galactic nuclei (AGN). Combining the extent of the Lyman-$α$ near-zones estimated from the blue peak velocity offset in these galaxies, with the ionizing emissivity of quasars at $z \gtrsim 6$, we forecast the intrinsic UV and X-ray luminosities of the AGN needed to give rise to their double-peaked profiles. We also estimate the extent of the obscuration of the AGN by comparing their luminosities to those of similar qu…
Deep narrow-band surveys have revealed a large population of faint Lyman-alpha (Lya) emitters (LAEs) in the distant Universe, but relatively little is known about the most luminous sources ($L_{Lyα}>10^{42.7}$ erg/s; $L_{Lyα}>L^*_{Lyα}$). Here we present the spectroscopic follow-up of 21 luminous LAEs at z~2-3 found with panoramic narrow-band surveys over five independent extragalactic fields (~4x10$^6$ Mpc$^{3}$ surveyed at z~2.2 and z~3.1). We use WHT/ISIS, Keck/DEIMOS and VLT/X-SHOOTER to study these sources using high ionisation UV lines. Luminous LAEs at z~2-3 have blue UV slopes ($β=-2.0…
Tracing ionized gas kinematics in Lyman-Break Analogs. Implications for star formation compactness and outflow properties
Universidad de La Serena(拉塞雷纳大学);Instituto de Astrofísica de Andalucía (CSIC)(安达卢西亚天体物理研究所);Centro de Estudios de Física del Cosmos de Aragón (CEFCA)(阿拉贡宇宙物理学研究中心);INAF - Osservatorio Astronomico di Roma(意大利国家天文台罗马天文台);Michigan Institute for Data Science, University of Michigan(密歇根大学数据科学研究所)
Local Lyman Break Galaxy Analogs: The Impact of Massive Star-forming Clumps on the Interstellar Medium and the Global Structure of Young, Forming Galaxies
We have observed the dust continuum of ten z=3.1 Lyman Break Galaxies with the Atacama Large Millimeter/Submillimeter Array at ~450 mas resolution in Band 7. We detect and resolve the 870um emission in one of the targets with an integrated flux density of S(870)=(192+/-57) uJy, and measure a stacked 3-sigma signal of S(870)=(67+/-23) uJy for the remaining nine. The total infrared luminosities estimated from full spectral energy distribution fits are L(8-1000um)=(8.4+/-2.3)x10^10 Lsun for the detection and L(8-1000um)=(2.9+/-0.9)x10^10 Lsun for the stack. With HST ACS I-band imaging we map the …
We propose that the origin of faint, broad emission-line wings in the Green Pea (GP) analog Mrk 71 is a clumpy, LyC and/or Ly$α$-driven superwind. Our spatially-resolved analysis of Gemini-N/GMOS-IFU observations shows that these line wings with terminal velocity $>3000~\rm{km~s^{-1}}$ originate from the super star cluster (SSC) Knot A, and propagate to large radii. The object's observed ionization parameter and stellar surface density are close to their theoretical maxima, and radiation pressure dominates over gas pressure. Together with a lack of evidence for supernova feedback, these imply …
Identifying low-redshift galaxies that emit Lyman Continuum radiation (LyC leakers) is one of the primary, indirect methods of studying galaxy formation in the epoch of reionization. However, not only has it proved challenging to identify such systems, it also remains uncertain whether the low-redshift LyC leakers are truly "analogues" of the sources that reionized the Universe. Here, we use high-resolution cosmological radiation hydrodynamics simulations to examine whether simulated galaxies in the epoch of reionization share similar emission line properties to observed LyC leakers at $z\sim3…
We present results on the nature of extreme ejective feedback episodes and the physical conditions of a population of massive ($\rm M_* \sim 10^{11} M_{\odot}$), compact starburst galaxies at z = 0.4-0.7. We use data from Keck/NIRSPEC, SDSS, Gemini/GMOS, MMT, and Magellan/MagE to measure rest-frame optical and near-IR spectra of 14 starburst galaxies with extremely high star formation rate surface densities (mean $\rm Σ_{SFR} \sim 3000 \,M_{\odot} yr^{-1} kpc^{-2}$) and powerful galactic outflows (maximum speeds v$_{98} \sim$ 1000-3000 km s$^{-1}$). Our unique data set includes an ensemble of …