Low-redshift compact star-forming galaxies as analogues of high-redshift star-forming galaxies

Izotov, Y. I.; Гусева, Н. Г.; Fricke, K. J.; Henkel, C.; Schaerer, D.; Thuan, T. X.

doi:10.1051/0004-6361/202039772

Cited by 47 publications

(66 citation statements)

References 138 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Nevertheless, we can see that the range of values that our survey covers overlaps with most of the range of the extremely metal poor and strongly star forming samples, in contrast with Yang et al (2017) and Cardamone et al (2009). In addition, we plot as well the typical values for other types of systems, some with strong ionizing spectra: HeII emitters (Pérez-Montero et al 2020) and Lyman α emitters (Matthee et al 2021;Izotov et al 2021). In these cases, their ratios are more similar to ours.…”

Section: Number Density Of Eelgsmentioning

confidence: 77%

“…The error bars represent the maximum and minimum value without outliers, which are plotted as dots (and defined as the values that lie beyond 1.5 times the inter quartilic range). We plot in this figure results from the present work and several samples from the literature (Yang et al 2017;Cardamone et al 2009;Amorín et al 2015;Onodera et al 2020;Hsyu et al 2018;Guseva et al 2017;Pérez-Montero et al 2020;Matthee et al 2021;Izotov et al 2021), as well as the KISS survey (Wegner et al 2003;Gronwall et al 2004;Jangren et al 2005;Salzer et al 2005) and the Hα dots class (Kellar et al 2012;Salzer et al 2020). We have selected the subsample with extremely low metallicity in Hsyu et al ( 2018) (H18_XMP), as well as those galaxies with EW(Hβ)>100 Å in both Hsyu et al (2018) XMPs (H18_XMP Hβ>100 Å) and the KISS survey (KISS Hβ>100 Å).…”

Section: Number Density Of Eelgsmentioning

confidence: 93%

See 1 more Smart Citation

J-PLUS: Uncovering a large population of extreme [OIII] emitters in the local Universe

Lumbreras-Calle¹,

López-Sanjuan²,

Sobral³

et al. 2021

Preprint

View full text Add to dashboard Cite

Context. Over the past decades, several studies have discovered a population of galaxies undergoing very strong star formation events, called extreme emission line galaxies (EELGs). Aims. In this work, we exploit the capabilities of the Javalambre Photometric Local Universe Survey (J-PLUS), a wide field multifilter survey, with 2000 square degrees of the northern sky already observed. We use it to identify EELGs at low redshift by their [OIII]5007 emission line. We intend to provide with a more complete, deep, and less biased sample of local EELGs. Methods. We select objects with an excess of flux in the J-PLUS mediumband J0515 filter, which covers the [OIII] line at z<0.06. We remove contaminants (stars and higher redshift systems) using J-PLUS and WISE infrared photometry, with SDSS spectra as a benchmark. We perform spectral energy distribution fitting to estimate the physical properties of the galaxies: line fluxes, equivalent widths (EWs), masses, stellar population ages, etc. Results. We identify 466 EELGs at z < 0.06 with [OIII] EW over 300 Å and r-band magnitude below 20, of which 411 were previously unknown. Most show compact morphologies, low stellar masses (log(M /M ) ∼ 8.13 +0.61 −0.58 ), low dust extinction (E(B−V) ∼ 0.1 +0.2 −0.1 ), and very young bursts of star formation (3.0 +2.7 −2.0 Myr). Our method is up to ∼ 20 times more efficient detecting EELGs per Mpc 3 than broadband surveys, and as complete as magnitude-limited spectroscopic surveys (while reaching fainter objects). The sample is not directly biased against strong Hα emitters, in contrast with works using broadband surveys. Conclusions. We demonstrate the capability of J-PLUS to identify, following a clear selection process, a large sample of previously unknown EELGs showing unique properties. A fraction of them are likely similar to the first galaxies in the Universe, but at a much lower redshift, which makes them ideal targets for follow-up studies.

show abstract

Section: Number Density Of Eelgsmentioning

confidence: 77%

Section: Number Density Of Eelgsmentioning

confidence: 93%

J-PLUS: Uncovering a large population of extreme [OIII] emitters in the local Universe

Lumbreras-Calle¹,

López-Sanjuan²,

Sobral³

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…7). To clarify this issue we need a systematic study of the detailed ISM and stellar populations of LAEs across redshift in the style of Izotov et al (2021b) who focused on compact star-forming galaxies.…”

Section: Caveats and Limitationsmentioning

confidence: 99%

The synchrony of production and escape: half the bright Lyα emitters at z ≈ 2 have Lyman continuum escape fractions ≈50

Naidu

Matthee

Oesch

et al. 2021

Monthly Notices of the Royal Astronomical Society

111

View full text Add to dashboard Cite

The ionizing photon escape fraction (LyC fesc) of star-forming galaxies is the single greatest unknown in the reionization budget. Stochastic sightline effects prohibit the direct separation of LyC leakers from non-leakers at significant redshifts. Here we circumvent this uncertainty by inferring fesc using resolved (R > 4000) Lyα profiles from the X-SHOOTER Lyα survey at z = 2 (XLS-z2). With empirically motivated criteria, we use Lyα profiles to select leakers (fesc$>20\%$) and non-leakers (fesc$<5\%$) from a representative sample of >0.2L* Lyman-α emitters (LAEs). We use median stacked spectra of these subsets over λrest ≈ 1000 − 8000Å to investigate the conditions for LyC fesc. Our stacks show similar mass, metallicity, MUV, and βUV. We find the following differences between leakers vs. non-leakers: (i) strong nebular CIV and HeII emission vs. non-detections, (ii) [O iii]/[O ii]≈8.5 vs. ≈3, (iii) Hα/Hβ indicating no dust vs. E(B − V) ≈ 0.3, (iv) MgII emission close to the systemic velocity vs. redshifted, optically thick MgII, (v) Lyα fesc of $\approx 50\%$ vs. $\approx 10\%$. The extreme EWs in leakers ([O iii]+Hβ ≈ 1100 Å rest-frame) constrain the characteristic timescale of LyC escape to ≈3 − 10 Myr bursts when short-lived stars with the hardest ionizing spectra shine. The defining traits of leakers – extremely ionizing stellar populations, low column densities, a dust-free, high ionization state ISM – occur simultaneously in the fesc$>20\%$ stack, suggesting they are causally connected, and motivating why indicators like [O iii]/[O ii] may suffice to constrain fesc at z > 6 with JWST. The leakers comprise half our sample, have a median LyC fesc$\approx 50\%$ (conservative range: $20-55\%$), and an ionising production efficiency $\log ({\xi _{\rm {ion}}/\rm {Hz\ erg^{-1}}})\approx 25.9$ (conservative range: 25.7 − 25.9). These results show LAEs – the type of galaxies rare at z ≈ 2, but that become the norm at higher redshift – are highly efficient ionizers, with extreme ξion and prolific fesc occurring in sync.

show abstract

“…Sources like Sunburst are unique laboratories to understand the physical mechanisms related to the escaping radiation at cosmological distance. This makes them very informative for the search of ionizing sources at earlier epochs during cosmic reionization (z > 6), when the LyC radiation cannot be observed directly due to high cosmic opacity rapidly increasing in the first 1.5 Gyr (Worseck et al 2014;Romano et al 2019) and are also key for comparison with LyC emitters identified in the local Universe (including candidates), considered analogs of the high redshift ones (Izotov et al 2021a;Schaerer et al 2016;Jaskot et al 2019;Wang et al 2021).…”

Section: Introductionmentioning

confidence: 99%

High star cluster formation efficiency in the strongly lensed Sunburst Lyman-continuum galaxy at z=2.37

Vanzella,

Castellano,

Bergamini

et al. 2021

Preprint

View full text Add to dashboard Cite

We investigate the strongly lensed (µ ×10 − 100) Lyman continuum (LyC) galaxy, dubbed Sunburst, at z = 2.37, taking advantage of a new accurate model of the lens. A characterization of the intrinsic (delensed) properties of the system yields a size of 3 sq.kpc, a luminosity M UV = −20.3, and a stellar mass M 10 9 M ; 16% of the ultraviolet light is located in a 3 Myr old gravitationally-bound young massive star cluster (YMC) with an effective radius of ∼ 8 pc (corresponding to 1 milli-arcsec without lensing) and a dynamical mass of ∼ 10 7 M (similar to the stellar mass), from which LyC radiation is detected (λ < 912Å). The star formation rate and stellar mass surface densities for the YMC are Log 10 (Σ SFR [M yr −1 kpc −2 ]) 3.7 and Log 10 (Σ M [M pc −2 ]) 4.1, with sSFR > 330 Gyr −1 , consistent with the values observed in local young massive star clusters. The inferred outflowing gas velocity (> 300 km s −1 ) exceeds the escape velocity of the cluster. The resulting relative escape fraction of the ionizing radiation emerging from the entire galaxy is higher than 6-12%, whilst it is 46 − 93% if inferred from the YMC multiple line of sights. At least 12 additional unresolved starforming knots with radii spanning the interval 3 − 20 pc (the majority of them likely gravitationally-bound star clusters) are identified in the galaxy. A significant fraction (40-60%) of the ultraviolet light of the entire galaxy is located in such bound star clusters. Adopting a formation timescale of the star clusters of 20 Myr we derive a cluster formation efficiency Γ 30%. The star formation rate surface density of the Sunburst galaxy (Log 10 (Σ SFR ) = 0.5 +3 −0.2 ) is consistent with the high inferred Γ, as observed in local galaxies experiencing extreme gas physical conditions. Overall, the presence of a bursty event (i.e., the 3 Myr old YMC with large sSFR) significantly influences the morphology (nucleation), photometry (photometric jumps) and spectroscopic output (nebular emission) of the entire galaxy. Without lensing magnification, the YMC would be associated to an unresolved 0.5 kpc−size star-forming clump. The de-lensed LyC and UV magnitude m 1600 (at 1600Å) of the YMC are 30.6 and 26.9, whilst the entire galaxy has m 1600 24.8. The Sunburst galaxy shows a relatively large rest-frame equivalent width of EW rest (Hβ+ [O iii]λλ4959, 5007) 450Å with the YMC contributing to ∼ 30% (having a local EW rest 1100Å) and ∼ 1% of the total stellar mass. If O-type (ionizing) stars are mainly forged in star clusters, then such engines were the key ionizing agents during reionization and the increasing occurrence of high equivalent width lines (Hβ+[Oiii]) observed at z > 6.5 might be an indirect signature of a high frequency of forming massive star clusters (or high Γ) at reionization. Future facilities, which will perform at few tens milli-arcsec resolution (e.g., VLT/MAVIS or ELT), will probe bound clusters on moderately magnified (µ < 5 − 10) galaxies across cosmic epochs up to reionization.

show abstract

Low-redshift compact star-forming galaxies as analogues of high-redshift star-forming galaxies

Cited by 47 publications

References 138 publications

J-PLUS: Uncovering a large population of extreme [OIII] emitters in the local Universe

J-PLUS: Uncovering a large population of extreme [OIII] emitters in the local Universe

The synchrony of production and escape: half the bright Lyα emitters at z ≈ 2 have Lyman continuum escape fractions ≈50

High star cluster formation efficiency in the strongly lensed Sunburst Lyman-continuum galaxy at z=2.37

Contact Info

Product

Resources

About