J/A+A/702/A3 HeII emitters. λ1640 emission (Gonzalez-Diaz+, 2025)
HeII emitters in the cosmic noon and beyond. Characterising the HeII
λ1640 emission with MUSE and JWST/NIRSpec.
Gonzalez-Diaz R., Vilchez J.M., Kehrig C., del Moral-Castro I.,
Iglesias-Paramo J.
<Astron. Astrophys. 702, A3 (2025)>
=2025A&A...702A...3G 2025A&A...702A...3G (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies ; Spectroscopy ; Optical ; Equivalent widths
Keywords: ISM: chemical abundances - galaxies: evolution -
galaxies: high redshift - galaxies: ISM - galaxies: star formation
Abstract:
The study of high-redshift galaxies provides critical insights into
the early stages of cosmic evolution, particularly during the
so-called 'cosmic noon', when star formation activity reached its
peak. Within this context, the origin of the nebular emission remains
an open question. In this work, we conduct a systematic,
multi-wavelength investigation of a sample of z∼2-4 emitters from the
MUSE Hubble Ultra Deep Field surveys, utilising both MUSE and
JWST/NIRSpec data and extending the sample presented by previous
studies. We derive gas-phase metallicities and key physical
properties, including electron densities, temperatures and the
production rates of hydrogen- and He+-ionising photons. Our results
suggest that a combination of factors-such as stellar mass, initial
mass function, stellar metallicity, and stellar multiplicity -- likely
contributes to the origin of the observed nebular emission.
Specifically, for our galaxies with higher gas-phase metallicity
(12+log(O/H)>7.55), we find that models for binary population with
Salpeter IMF (Mup=100M☉) and stellar metallicity ∼0.001 (i.e.,
similar to that of the gas) can reproduce the observed ionising
conditions. However at lower metallicities, models for binary
population with 'top-heavy' initial mass function (Mup=300M☉)
and Z* much lower (10-4<Z*<10-5) than that of the gas are required
to fully account for the observed ionising photon production. These
results reinforce that the ionisation keeps challenging current
stellar populations, and the ionisation problem persists in the very
low metallicity regime.
Description:
We performed a physical and chemical characterisation of a sample of
galaxies at z∼2-4 exhibiting prominent nebular HeII λ1640Å
emission, commonly referred to as HeII emitters. Our sample was
selected from the MUSE Hubble Ultra Deep Field surveys (MHUDF) --
expanding upon the samples used by previous authors', which include
three MUSE fields: the MUSE Extremely Deep Field (MXDF), the Ultra
Deep Field survey (UDF-10), and the MOSAIC field. We used the publicly
available AMUSED database to identify potential HeII emitters.
From a total of 2221 objects in the MHUDF, we identified 25 galaxies
exhibiting nebular HeII λ1640Å emission with signal-to-noise
ratios greater than 3, spanning a redshift range of 1.907<z<4.41.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 122 25 General characteristics of the HeII emitters sample
tableb2.dat 755 54 Sample UV lines fluxes measured with MUSE
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See also:
J/A+A/670/A4 : MUSE Hubble Ultra Deep Field surveys. DR2 (Bacon+, 2023)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Identification number (1)
5 A1 --- n_ID [*b] Note (2)
7- 8 I2 h RAh Right ascension (J2000) (1)
10- 11 I2 min RAm Right ascension (J2000) (1)
13- 18 F6.3 s RAs Right ascension (J2000) (1)
20 A1 --- DE- Declination sign (J2000) (1)
21- 22 I2 deg DEd Declination (J2000) (1)
24- 25 I2 arcmin DEm Declination (J2000) (1)
27- 32 F6.3 arcsec DEs Declination (J2000) (1)
34- 38 F5.1 0.1nm EWLya ?=- Lymanα equivalent width
40- 43 F4.1 0.1nm e_EWLya ? Lymanα equivalent width error
45- 48 F4.1 0.1nm EWHeII HeII equivalent width
50- 52 F3.1 0.1nm e_EWHeII HeII equivalent width error
54- 58 F5.3 --- z Redshift
60- 65 F6.3 [Msun] logM* ?=- Stellar mass (1)
66 A1 --- --- [+]
67- 71 F5.3 [Msun] E_logM* ? Stellar mass error (upper value) (1)
72 A1 --- --- [-]
73- 77 F5.3 [Msun] e_logM* ? Stellar mass error (lower value) (1)
79- 84 F6.3 [Msun/yr] logSFR ?=- Star formation rate (1)
85 A1 --- --- [+]
86- 90 F5.3 [Msun/yr] E_logSFR ? Star formation rate error (upper value) (1)
91 A1 --- --- [-]
92- 96 F5.3 [Msun/yr] e_logSFR ? Star formation rate error (lower value) (1)
98-102 F5.3 mag AV ?=- Extinction in V band (3)
104-108 F5.3 mag e_AV ? Absorption in V band error
110-116 F7.3 mag M1500 ?=- Absolute magnitude at the 1500Å band
118-122 F5.3 mag e_M1500 ? Absolute magnitude at the 1500Å band
error
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Note (1): ID, RA, DEC, z, M* and SFR values were taken from the AMUSED database
(Bacon et al., 2023A&A...670A...4B 2023A&A...670A...4B, Cat. J/A+A/670/A4).
For galaxies with ID: 7898, 8249 and 103, the SED was not performed due to the
lack of HST photometric data. Consequently, the M* and SFR values were not
calculated and are left as blank spaces in the table.
Note (2): The AV obtained using the Paschen series for the galaxies marked by an
asterisk can be found in table 1. The two AGNs (ID:1056 and ID:1051) which
present broad HeII, [CIII] and CIV features are marked with a b.
Note (3): The AV from the beta slope, M1500 and rest-frame EWs were calculated
in this work (see section 2.1).
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Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
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1- 14 A14 --- Line MUSE line ID
16- 24 F9.3 10-23W/m2 F7898 ? Line flux of the galaxy ID: 7898
26- 34 F9.3 10-23W/m2 e_F7898 ? Line flux error of the galaxy ID: 7898
36- 44 F9.3 0.1nm FWHM7898 ? Line FWHM of the galaxy ID: 7898
46- 54 F9.3 10-23W/m2 F8249 ? Line flux of the galaxy ID: 8249
56- 64 F9.3 10-23W/m2 e_F8249 ? Line flux error of the galaxy ID: 8249
66- 74 F9.3 0.1nm FWHM8249 ? Line FWHM of the galaxy ID: 8249
76- 84 F9.3 10-23W/m2 F1059 ? Line flux of the galaxy ID: 1059
86- 94 F9.3 10-23W/m2 e_F1059 ? Line flux error of the galaxy ID: 1059
96-104 F9.3 0.1nm FWHM1059 ? Line FWHM of the galaxy ID: 1059
106-114 F9.3 10-23W/m2 F1141 ? Line flux of the galaxy ID: 1141
116-124 F9.3 10-23W/m2 e_F1141 ? Line flux error of the galaxy ID: 1141
126-134 F9.3 0.1nm FWHM1141 ? Line FWHM of the galaxy ID: 1141
136-143 F8.3 10-23W/m2 F50 ? Line flux of the galaxy ID: 50
145-152 F8.3 10-23W/m2 e_F50 ? Line flux error of the galaxy ID: 50
154-161 F8.3 0.1nm FWHM50 ? Line FWHM of the galaxy ID: 50
163-171 F9.3 10-23W/m2 F6664 ? Line flux of the galaxy ID: 6664
173-181 F9.3 10-23W/m2 e_F6664 ? Line flux error of the galaxy ID: 6664
183-191 F9.3 0.1nm FWHM6664 ? Line FWHM of the galaxy ID: 6664
193-201 F9.3 10-23W/m2 F8165 ? Line flux of the galaxy ID: 8165
203-211 F9.3 10-23W/m2 e_F8165 ? Line flux error of the galaxy ID: 8165
213-221 F9.3 0.1nm FWHM8165 ? Line FWHM of the galaxy ID: 8165
223-231 F9.3 10-23W/m2 F149 ? Line flux of the galaxy ID: 149
233-241 F9.3 10-23W/m2 e_F149 ? Line flux error of the galaxy ID: 149
243-251 F9.3 0.1nm FWHM149 ? Line FWHM of the galaxy ID: 149
253-261 F9.3 10-23W/m2 F8414 ? Line flux of the galaxy ID: 8414
263-271 F9.3 10-23W/m2 e_F8414 ? Line flux error of the galaxy ID: 8414
273-281 F9.3 0.1nm FWHM8414 ? Line FWHM of the galaxy ID: 8414
283-290 F8.3 10-23W/m2 F103 ? Line flux of the galaxy ID: 103
292-299 F8.3 10-23W/m2 e_F103 ? Line flux error of the galaxy ID: 103
301-308 F8.3 0.1nm FWHM103 ? Line FWHM of the galaxy ID: 103
310-319 F10.3 10-23W/m2 F3621 ? Line flux of the galaxy ID: 3621
321-330 F10.3 10-23W/m2 e_F3621 ? Line flux error of the galaxy ID: 3621
332-341 F10.3 0.1nm FWHM3621 ? Line FWHM of the galaxy ID: 3621
343-351 F9.3 10-23W/m2 F8369 ? Line flux of the galaxy ID: 8369
353-361 F9.3 10-23W/m2 e_F8369 ? Line flux error of the galaxy ID: 8369
363-371 F9.3 0.1nm FWHM8369 ? Line FWHM of the galaxy ID: 8369
373-381 F9.3 10-23W/m2 F6700 ? Line flux of the galaxy ID: 6700
383-391 F9.3 10-23W/m2 e_F6700 ? Line flux error of the galaxy ID: 6700
393-401 F9.3 0.1nm FWHM6700 ? Line FWHM of the galaxy ID: 6700
403-411 F9.3 10-23W/m2 F1045 ? Line flux of the galaxy ID: 1045
413-421 F9.3 10-23W/m2 e_F1045 ? Line flux error of the galaxy ID: 1045
423-431 F9.3 0.1nm FWHM1045 ? Line FWHM of the galaxy ID: 1045
433-441 F9.3 10-23W/m2 F6999 ? Line flux of the galaxy ID:6999
443-451 F9.3 10-23W/m2 e_F6999 ? Line flux error of the galaxy ID:6999
453-461 F9.3 0.1nm FWHM6999 ? Line FWHM of the galaxy ID:6999
463-470 F8.3 10-23W/m2 F164 ? Line flux of the galaxy ID: 164
472-479 F8.3 10-23W/m2 e_F164 ? Line flux error of the galaxy ID: 164
481-488 F8.3 0.1nm FWHM164 ? Line FWHM of the galaxy ID: 164
490-498 F9.3 10-23W/m2 F6666 ? Line flux of the galaxy ID: 6666
500-508 F9.3 10-23W/m2 e_F6666 ? Line flux error of the galaxy ID: 6666
510-518 F9.3 0.1nm FWHM6666 ? Line FWHM of the galaxy ID: 6666
520-528 F9.3 10-23W/m2 F1024 ? Line flux of the galaxy ID: 1024
530-538 F9.3 10-23W/m2 e_F1024 ? Line flux error of the galaxy ID: 1024
540-548 F9.3 0.1nm FWHM1024 ? Line FWHM of the galaxy ID: 1024
550-558 F9.3 10-23W/m2 F1273 ? Line flux of the galaxy ID: 1273
560-568 F9.3 10-23W/m2 e_F1273 ? Line flux error of the galaxy ID: 1273
570-578 F9.3 0.1nm FWHM1273 ? Line FWHM of the galaxy ID: 1273
580-587 F8.3 10-23W/m2 F22 ? Line flux of the galaxy ID: 22
589-596 F8.3 10-23W/m2 e_F22 ? Line flux error of the galaxy ID: 22
598-605 F8.3 0.1nm FWHM22 ? Line FWHM of the galaxy ID: 22
607-615 F9.3 10-23W/m2 F1036 ? Line flux of the galaxy ID: 1036
617-625 F9.3 10-23W/m2 e_F1036 ? Line flux error of the galaxy ID: 1036
627-635 F9.3 0.1nm FWHM1036 ? Line FWHM of the galaxy ID: 1036
637-645 F9.3 10-23W/m2 F1056 ? Line flux of the galaxy ID: 1056
647-655 F9.3 10-23W/m2 e_F1056 ? Line flux error of the galaxy ID: 1056
657-665 F9.3 0.1nm FWHM1056 ? Line FWHM of the galaxy ID: 1056
667-675 F9.3 10-23W/m2 F1051 ? Line flux of the galaxy ID:1051
677-685 F9.3 10-23W/m2 e_F1051 ? Line flux error of the galaxy ID:1051
687-695 F9.3 0.1nm FWHM1051 ? Line FWHM of the galaxy ID:1051
697-705 F9.3 10-23W/m2 F106 ? Line flux of the galaxy ID 106
707-715 F9.3 10-23W/m2 e_F106 ? Line flux error of the galaxy ID 106
717-725 F9.3 0.1nm FWHM106 ? Line FWHM of the galaxy ID 106
727-735 F9.3 10-23W/m2 F51 ? Line flux of the galaxy ID: 51
737-745 F9.3 10-23W/m2 e_F51 ? Line flux error of the galaxy ID: 51
747-755 F9.3 0.1nm FWHM51 ? Line flux error of the galaxy ID: 51
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Acknowledgements:
Raul Gonzalez-Diaz, ragonzalez(at)iaa.es
(End) Patricia Vannier [CDS] 05-Aug-2025