J/MNRAS/482/2530 Young massive clusters in LIRG Arp 299 (Randriamanakoto+, 2019)
Young massive clusters in the interacting LIRG Arp 299: evidence for the
dependence of star cluster formation and evolution on environment.
Randriamanakoto Z., Vaisanen P., Ryder S.D., Ranaivomanana P.
<Mon. Not. R. Astron. Soc., 482, 2530-2554 (2019)>
=2019MNRAS.482.2530R 2019MNRAS.482.2530R (SIMBAD/NED BibCode)
ADC_Keywords: Galaxies, photometry ; Optical
Keywords: galaxies: individual: Arp 299, NGC 3690E, NGC 3690W -
galaxies: interactions - galaxies: star clusters: general
Abstract:
Archival WFC3/UVIS imaging of Arp 299 (NGC3690E+NGC3690W) is retrieved
to investigate the young massive cluster (YMC) population of this
ongoing merger. We extract 2182 cluster candidates, including 1323
high confidence photometric sources. Multiband photometry is matched
with Yggdrasil models to estimate the age, mass, and extinction of
each cluster. A Schechter fit of the truncated cluster mass function
results in a characteristic mass M*=1.6x106M☉. Ou results
confirm that intensely star-forming galaxies such as Arp299 host more
massive clusters than quiescent dwarf and normal spirals. In the case
of NGC3690E, we find that the cluster masses decrease with an
increasing galactocentric radius likely due to the gas density
distribution. On the other hand, the fitted age distributions of a
mass-limited sample suggest that YMCs of the western component undergo
stronger disruption than those hosted by the eastern galaxy. This is
in agreement with the properties of the underlying cluster luminosity
functions: a clear truncation at high luminosities with slopes
generally shallower by ∼0.3dex than the ones of the NGC3690E. Finally,
the derived cluster formation efficiency, Γ∼19 per cent,
indicates that Arp299 has ∼3-5 times more star formation happening in
bound clusters compared to the cases of gas-poor spirals like NGC2997
and NGC4395. The merger generally follows the Γ - star formation
rate density relation from the literature. The YMC photometric study
of Arp299 thus reveals that both formation and disruption mechanisms
of the star cluster population are most likely environment dependent.
Description:
We retrieved already-processed WFC3/UVIS images of Arp299 from the
publicly available Hubble Legacy Archive (HLA3) (http://hla.stsci.edu)
in the following broad-band filters: F336W(U,790s), F438W(B,740s), and
F814W(I,740s). The plate scale is 0.039arcsec/pixel and the point
spread function (PSF) values for the point sources vary between 0.07
and 0.09arcsec depending on the filter. Compared to previous HST
instruments such as WFPC2 and WFC/ACS, the WFC3/UVIS camera provides
sharper images with a more stable PSF. Furthermore, the use of deep
U-band data will help to constrain the cluster age-extinction
degeneracy and to develop a more accurate approach on how to interpret
results from BIK-band YMC analyses.
Only objects with SNR≥5 in all three filters were initially
considered in order to output a catalogue of 1323 high confidence
photometric SSC candidates. This number comes from cross-matching
1491, 1879, and 1913 objects that satisfy the conditions in the
individual fields of U, B, and I bands, respectively. However, both
the visual inspection and data point distribution indicate that a
significant number of obvious SSCs would be rejected by applying such
criteria in the photometric errors. Therefore, to draw our final
UBI-band catalogue of 2182 star cluster candidates, we set a cut-off
of σm=0.35mag as a trade-off and also included 116 extra
candidates clearly visible in all three filters but with a relatively
high uncertainty in their U-band magnitudes (σU=<0.50mag).
Nevertheless, we investigated the effects of photometric biases using
the final catalogue that turned out to be insignificant. The UBI-band
apparent magnitudes with their uncertainties are presented in Table 3.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 79 2182 Catalogue of the SSC candidates in the field
of Arp299
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID Super star cluster (SCS) candidate
identification
6- 18 F13.9 deg RAdeg Right ascension (J2000)
20- 31 F12.9 deg DEdeg Declination (J2000)
33- 37 F5.2 mag Umag Vega-based apparent magnitude in the U-band
(F336W)
39- 42 F4.2 mag e_Umag Error on instrumental Umag (1)
44- 48 F5.2 mag Bmag Vega-based apparent magnitude in the B-band
(F438W)
50- 53 F4.2 mag e_Bmag Error on instrumental Bmag (1)
55- 59 F5.2 mag Imag Vega-based apparent magnitude in the I-band
(F814W)
61- 64 F4.2 mag e_Imag Error on instrumental Imag (1)
66- 69 F4.2 mag AV Derived extinction
71- 74 F4.2 [yr] Age Log of cluster age
76- 79 F4.2 [Msun] Mass Log of cluster mass
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Note (1): Do not forget to add the systematic error from photometric calibration
to get the uncertainty in the apparent magnitude: 0.01(U), 0.04(B),
0.01(I).
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History:
From electronic version of the journal
(End) Ana Fiallos [CDS] 30-Jun-2022