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By combining HST imaging with optical (VIMOS) and near-infrared (SINFONI) integral field spectroscopy we exploit the gravitational potential of a massive, rich cluster at z=0.9 to study the internal properties of a gravitationally lensed…

One of the key questions in observational cosmology is the identification of the sources responsible for ionisation of the Universe after the cosmic Dark Ages, when the baryonic matter was neutral. The currently identified distant galaxies…

Astrophysics of Galaxies · Physics 2016-01-14 Y. I. Izotov , I. Orlitova , D. Schaerer , T. X. Thuan , A. Verhamme , N. Guseva , G. Worseck

The physical conditions giving rise to high escape fractions of ionizing radiation (LyC $f_{\rm{esc}}$) in star-forming galaxies - most likely protagonists of cosmic reionization - are not yet fully understood. Using the VLT/MUSE…

Astrophysics of Galaxies · Physics 2024-01-09 I. G. Kramarenko , J. Kerutt , A. Verhamme , P. A. Oesch , L. Barrufet , J. Matthee , H. Kusakabe , I. Goovaerts , T. T. Thai

We present observations with the Cosmic Origins Spectrograph onboard the Hubble Space Telescope of seven compact low-mass star-forming galaxies at redshifts, z,in the range 0.3161-0.4276, with various O3Mg2=[OIII]5007/MgII 2796+2803 and…

Astrophysics of Galaxies · Physics 2022-08-08 Y. I. Izotov , J. Chisholm , G. Worseck , N. G. Guseva , D. Schaerer , J. X. Prochaska

We propose to infer ionising continuum leaking properties of galaxies by looking at their Lyman-alpha line profiles. We carry out Lyman-alpha radiation transfer calculations in two models of HII regions which are porous to ionising…

Astrophysics of Galaxies · Physics 2015-05-27 A. Verhamme , I. Orlitova , D. Schaerer , M. Hayes

A population of early star-forming galaxies is the leading candidate for the re-ionization of the universe. It is still unclear what conditions and physical processes would enable a significant fraction of the ionizing photons to escape…

Astrophysics of Galaxies · Physics 2015-09-16 Rachael Alexandroff , Timothy Heckman , Sanchayeeta Borthakur , Roderik Overzier , Claus Leitherer

(Abridged) Deep NB359 imaging with Subaru by Iwata et al. have detected surprisingly strong Lyman continuum (LyC; ~900A in the rest-frame) from some LAEs at z=3.1. However, the redshifts might be misidentified due to a narrow wavelength…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Akio K. Inoue , K. Kousai , I. Iwata , Y. Matsuda , E. Nakamura , M. Horie , T. Hayashino , C. Tapken , M. Akiyama , S. Noll , T. Yamada , D. Burgarella

To reionize the early universe, high-energy photons must escape the galaxies that produce them. It has been suggested that stellar feedback drives galactic outflows out of star-forming regions, creating low density channels through which…

Astrophysics of Galaxies · Physics 2017-09-13 J. Chisholm , I. Orlitová , D. Schaerer , A. Verhamme , G. Worseck , Y. I. Izotov , T. X. Thuan , N. G. Guseva

Although Lyman continuum (LyC) radiation from star-forming galaxies likely drove the reionization of the Universe, observations of star-forming galaxies at low redshift generally indicate low LyC escape fractions. However, the extreme [O…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 A. E. Jaskot , M. S. Oey

We investigate the contribution of star-forming galaxies to the ionizing background at z~3, building on previous work based on narrowband (NB3640) imaging in the SSA22a field. We use new Keck/LRIS spectra of Lyman break galaxies (LBGs) and…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-11 Daniel B. Nestor , Alice E. Shapley , Katherine A. Kornei , Charles C. Steidel , Brian Siana

The origin of Lyman Continuum (LyC) photons responsible for reionizing the universe remains a mystery, with the fraction of escaping LyC photons from galaxies at z$\sim$ 6 to 12 being highly uncertain. While direct detection of LyC photons…

Combining 66 ultraviolet (UV) spectra and ancillary data from the Low-Redshift Lyman Continuum Survey (LzLCS) and 23 LyC observations by earlier studies, we form a statistical sample of star-forming galaxies at $z \sim 0.3$ to study the…

The properties that govern the production and escape of hydrogen ionizing photons (Lyman continuum, LyC; with energies >13.6 eV) in star-forming galaxies are still poorly understood, but they are key to identifying and characterizing the…

Using Integral Field Unit (IFU) spectroscopy, we present here the spatially resolved morphologies of [SII]$\lambda$6717,6731/H$\alpha$ and [SII]$\lambda$6717,6731/[OIII]$\lambda$5007 emission line ratios for the first time in a Blueberry…

Astrophysics of Galaxies · Physics 2022-01-19 Abhishek Paswan , Kanak Saha , Claus Leitherer , Daniel Schaerer

Spatially resolved studies of high redshift galaxies, an essential insight into galaxy formation processes, have been mostly limited to stacking or unusually bright objects. We present here the study of a typical (L$^{*}$, M$_\star$ = 6…

We report the results of a study of the rest-frame UV spectrum of the Cosmic Eye, a luminous Lyman break galaxy at z=3.07331 gravitationally lensed by a factor of 25. The spectrum, recorded with the ESI spectrograph on the Keck II…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Anna M. Quider , Alice E. Shapley , Max Pettini , Charles C. Steidel , Daniel P. Stark

Distant luminous Lyman-alpha emitters are excellent targets for detailed observations of galaxies in the epoch of reionisation. Spatially resolved observations of these galaxies allow us to simultaneously probe the emission from young…

Astrophysics of Galaxies · Physics 2020-06-10 Jorryt Matthee , David Sobral

We study the kinematically narrow, low-ionization line emission from a bright, starburst galaxy at z = 0.69 using slit spectroscopy obtained with Keck/LRIS. The spectrum reveals strong absorption in MgII and FeII resonance transitions with…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Kate H. R. Rubin , J. Xavier Prochaska , Brice Ménard , Norman Murray , Daniel Kasen , David C. Koo , Andrew C. Phillips

We report the detection of 5 newly identifed Lyman-continuum (LyC) leaker candidates at redshifts 0.99-1.42 in the AstroSat UV Deep Field South F154W image. We derive physical properties of these galaxies using a combination of…

Astrophysics of Galaxies · Physics 2025-03-13 Soumil Maulick , Kanak Saha , Michael J. Rutkowski

Reionization is an inhomogeneous process, thought to begin in small ionized bubbles of the intergalactic medium (IGM) around overdense regions of galaxies. Recent Lyman-alpha (Ly$\alpha$) studies during the epoch of reionization show…