ALMA observations of 99 GHz free–free and H40α line emission from star formation in the centre of NGC 253

Bendo, G. J.; Beswick, R. J.; D'Cruze, Michael; Dickinson, C.; Fuller, G. A.; Muxlow, T. W. B.

doi:10.1093/mnrasl/slv053

Cited by 65 publications

(86 citation statements)

References 28 publications

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“…If no rotation was included in the derivation of the relation between SFR and Q, the coefficient in Equation 11 would be very similar to the Murphy et al (2011) coefficient. The additional difference between the Kennicutt (1998) and Bendo et al (2015b) coefficients is related to the difference between the Kennicutt (1998) and Murphy et al (2011) coefficients. As discussed by Calzetti et al (2007), this could be attributed to assumptions regarding the IMF and star formation history.…”

Section: Star Formation Rates From Alma Datamentioning

confidence: 96%

“…Peel et al 2011), synchrotron and thermal dust emission could contribute a significant fraction of the emission at this frequency (e.g. Bendo et al 2015b). To use the continuum emission to estimate both Te and SFR, we need to remove the other continuum emission sources from the free-free emission.…”

Section: Spectral Energy Distributionmentioning

confidence: 99%

“…which was derived by Bendo et al (2015b) using version 7.0.1 of the STARBURST99 models (Leitherer et al 1999(Leitherer et al , 2014. The conversion was derived using Z = 0.040 metallicity 9 , a Kroupa (2002) initial mass function (IMF) for a mass range of 0.1-100 M⊙, and the average of results from the Geneva evolutionary tracks that include no stellar rotation and rotation at 40% of the break-up velocity 10 The SFR is assumed to be continuous and to have been T 0.31 ± 0.04 12.9 ± 0.8 42 ± 5 5400 ± 600 N 0.054 ± 0.007 2.5 ± 0.1 46 ± 6 5000 ± 600 C 0.111 ± 0.015 3.9 ± 0.2 35 ± 4 6300 ± 700 S 0.042 ± 0.006 1.9 ± 0.1 45 ± 5 5100 ± 600 a The free-free flux densities are based on the continuum flux densities in these apertures multiplied by 0.84 ± 0.10.…”

Section: Star Formation Rates From Alma Datamentioning

confidence: 99%

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Free–free and H42α emission from the dusty starburst within NGC 4945 as observed by ALMA

Bendo¹,

Henkel²,

D'Cruze³

et al. 2016

Mon. Not. R. Astron. Soc.

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We present observations of the 85.69 GHz continuum emission and H42α line emission from the central 30 arcsec within NGC 4945. Both sources of emission originate from nearly identical structures that can be modelled as exponential discs with a scale length of ∼2.1 arcsec (or ∼40 pc). An analysis of the spectral energy distribution based on combining these data with archival data imply that 84%±10% of the 85.69 GHz continuum emission originates from free-free emission. The electron temperature is 5400±600 K, which is comparable to what has been measured near the centre of the Milky Way Galaxy. The star formation rate (SFR) based on the H42α and 85.69 GHz free-free emission (and using a distance of 3.8 Mpc) is 4.35±0.25 M ⊙ yr −1 . This is consistent with the SFR from the total infrared flux and with previous measurements based on recombination line emission, and it is within a factor of ∼2 of SFRs derived from radio data. The Spitzer Space Telescope 24 µm data and Wide-field Infrared Survey Explorer 22 µm data yield SFRs ∼10× lower than the ALMA measurements, most likely because the mid-infrared data are strongly affected by dust attenuation equivalent to A V = 150. These results indicate that SFRs based on mid-infrared emission may be highly inaccurate for dusty, compact circumnuclear starbursts.

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Section: Star Formation Rates From Alma Datamentioning

confidence: 96%

Section: Spectral Energy Distributionmentioning

confidence: 99%

Section: Star Formation Rates From Alma Datamentioning

confidence: 99%

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Free–free and H42α emission from the dusty starburst within NGC 4945 as observed by ALMA

Bendo¹,

Henkel²,

D'Cruze³

et al. 2016

Mon. Not. R. Astron. Soc.

Self Cite

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“…The contribution could account for up to 20% of 353 GHz continuum flux density, which is estimated by extrapolating the 99 GHz free-free flux density given by Bendo et al (2015). Note that, however, this estimate is just an upper-limit, since the observations conducted by Bendo et al (2015) covered the emission from larger spatial scale than we do, as the minimum baseline length of their observations (7.0kλ; Bendo et al 2015) is half as long as that of ours (15.3kλ). Although the estimate of dust masses of the clumps presented in Table 1 needs to be slightly reduced, the correction up to 20% does not affect the comparison of the scales of the clumps.…”

Section: Line Profiles and Emission Parametersmentioning

confidence: 99%

Diverse Nuclear Star-forming Activities in the Heart of NGC 253 Resolved with 10-pc-scale ALMA Images

Ando

Nakanishi

Kohno

et al. 2017

ApJ

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We present an 8 pc × 5 pc resolution view of the central ∼ 200 pc region of the nearby starburst galaxy NGC 253, based on ALMA Band 7 (λ 0.85 mm or ν ∼ 350 GHz) observations covering 11 GHz. We resolve the nuclear starburst of NGC 253 into eight dusty star-forming clumps, 10 pc in scale, for the first time. These clumps, each of which contains (4-10) ×10 4 M of dust (assuming that the dust temperature is 25 K) and up to 6 × 10 2 massive (O5V) stars, appear to be aligned in two parallel ridges, while they have been blended in previous studies. Despite the similarities in sizes and dust masses of these clumps, their line spectra vary drastically from clump to clump although they are separated by only ∼ 10 pc. Specifically, one of the clumps, Clump 1, exhibits line confusion-limited spectra with at least 36 emission lines from 19 molecules (including CH 3 OH, HNCO, H 2 CO, CH 3 CCH, H 2 CS, and H 3 O + ) and a hydrogen recombination line (H26α), while much fewer kinds of molecular 3 lines are detected in some other clumps where fragile species, such as complex organic molecules and HNCO, completely disappear from their spectra. We demonstrate the existence of hot molecular gas (T rot (SO 2 ) = 90 ± 11 K) in the former clump, which suggests that the hot and chemically rich environments are localized within a 10-pc scale star-forming clump.

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“…, and the star formation rate is ∼5 M e yr −1 (Lenc & Tingay 2006;Rampadarath et al 2014;Bendo et al 2015;Lucero et al 2015). It has been suggested that up to half of the radio sources in the central starburst region are dominated by thermal emission, i.e., H II regions characterized by a flat radio spectral index 24 α;0.1 and including at least one large supercluster of stars (Ulvestad & Antonucci 1997;Keto et al 1999).…”

Section: Introductionmentioning

confidence: 99%

Spectral Energy Distribution and Radio Halo of NGC 253 at Low Radio Frequencies

Kapińska

Staveley‐Smith

Crocker

et al. 2017

ApJ

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We present new radio continuum observations of NGC253 from the Murchison Widefield Array at frequencies between 76 and 227 MHz. We model the broadband radio spectral energy distribution for the total flux density of NGC253 between 76 MHz and 11 GHz. The spectrum is best described as a sum of a central starburst and extended emission. The central component, corresponding to the inner 500 pc of the starburst region of the galaxy, is best modeled as an internally free-free absorbed synchrotron plasma, with a turnover frequency around 230 MHz. The extended emission component of the spectrum of NGC253 is best described as a synchrotron emission flattening at low radio frequencies. We find that 34% of the extended emission (outside the central starburst region) at 1 GHz becomes partially absorbed at low radio frequencies. Most of this flattening occurs in the western region of the southeast halo, and may be indicative of synchrotron self-absorption of shock-reaccelerated electrons or an intrinsic low-energy cutoff of the electron distribution. Furthermore, we detect the large-scale synchrotron radio halo of NGC253 in our radio images. At 154-231 MHz the halo displays the well known X-shaped/horn-like structure, and extends out to ∼8 kpc in the z-direction (from the major axis).

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ALMA observations of 99 GHz free–free and H40α line emission from star formation in the centre of NGC 253

Cited by 65 publications

References 28 publications

Free–free and H42α emission from the dusty starburst within NGC 4945 as observed by ALMA

Free–free and H42α emission from the dusty starburst within NGC 4945 as observed by ALMA

Diverse Nuclear Star-forming Activities in the Heart of NGC 253 Resolved with 10-pc-scale ALMA Images

Spectral Energy Distribution and Radio Halo of NGC 253 at Low Radio Frequencies

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