J/ApJ/916/58 HST obs. of supernova remnants in NGC6946 (Koplitz+, 2021)
The masses of supernova remnant progenitors in NGC 6946.
Koplitz B., Johnson J., Williams B.F., Long K.S., Blair W.P., Murphy J.W.,
Dolphin A., Hillis T.
<Astrophys. J., 916, 58 (2021)>
=2021ApJ...916...58K 2021ApJ...916...58K
ADC_Keywords: Supernova remnants; Galaxies, nearby; Photometry, HST; Optical;
Stars, masses; Stars, ages; Reddening; Supernovae; Black holes
Keywords: Supernovae ; Stellar evolution ; Massive stars ; Stellar populations
Abstract:
We constrained the progenitor masses for 169 supernova remnants
(SNRs), eight historically observed supernovae (SNe), and the black
hole formation candidate in NGC 6946, finding that they are consistent
with originating from a standard initial mass function. Additionally,
there were 16 remnants that showed no sign of nearby star formation
consistent with a core-collapse SN, making them good Type Ia
candidates. Using Hubble Space Telescope broadband imaging, we
measured the stellar photometry of ACS/WFC fields in the F435W, F555W,
F606W, and F814W filters, as well as WFC3/UVIS fields in F438W, F606W,
and F814W. We then fitted this photometry with stellar evolutionary
models to determine the ages of the young populations present at the
positions of the SNRs and SNe. We then inferred a progenitor mass
probability distribution from the fitted age distribution. For 37
SNRs, we tested how different filter combinations affected the
inferred masses. We find that filters sensitive to Hα, [NII],
and [SII] gas emission can bias mass estimates for remnants that rely
on our technique. Using a Kolmogorov-Smirnov test analysis on our most
reliable measurements, we find that the progenitor mass distribution
is well matched by a power-law index of -2.6-0.6+0.5, which is
consistent with a standard initial mass function.
Description:
We analyze HST observations made using the Advanced Camera for Surveys
(ACS) instrument with Wide-Field Channel (WFC) F435W, F555W, F606W,
and F814W filters and the Wide-Field Camera 3 (WFC3) instrument with
Ultraviolet-Visible channel (UVIS) F438W, F606W, and F814W filters.
The specific observations that we included in our analysis, along with
their exposure details, are listed in Table 1 and span 2010-08-07 to
2019-01-27. The sum of our observations covers most of the main body
of the disk of NGC 6946 and can be seen in Figure 1.
Objects:
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RA (ICRS) DE Designation(s)
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20 34 52.33 +60 09 13.2 NGC 6946 = UGC 11597
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 70 119 NGC 6946 observations
table2.dat 67 178 SNR photometry depth, extinction, and progenitor
mass estimates
table3.dat 47 236 NGC 6946 supernova remnants
table4.dat 100 3916 Age probability distribution results
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See also:
B/hst : HST Archived Exposures Catalog (STScI, 2007)
IX/57 : The Chandra Source Catalog (CSC), Release 2.0 (Evans+, 2019)
J/MNRAS/395/1409 : Type II-P SN progenitor constraints (Smartt+, 2009)
J/ApJ/703/370 : Radio SNRs in nearby galaxies (Chomiuk+, 2009)
J/A+A/545/A43 : HII regions in NGC 628 and NGC 6946 (Cedres+, 2012)
J/A+A/538/A120 : A unified supernova catalogue (Lennarz+, 2012)
J/A+A/552/A19 : Radio-farIR correlation in NGC 6946 (Tabatabaei+, 2013)
J/ApJ/795/170 : Sample SNRs for M31 and M33 (Jennings+, 2014)
J/ApJ/789/147 : Star formation histories of LG dwarf galaxies (Weisz+, 2014)
J/ApJS/215/9 : PHAT X. UV-IR photometry of M31 stars (Williams+, 2014)
J/ApJ/791/105 : SNe progenitor masses prob. distribution (Williams+, 2014)
J/ApJ/846/145 : PHAT. XIX. Formation history of M31 disk (Williams+, 2017)
J/ApJ/860/39 : HST obs. of nearby core-collapse SNe (Williams+, 2018)
J/MNRAS/484/1899 : The ASAS-SN bright supernova catalogue - IV (Holoien+, 2019)
J/ApJ/875/85 : SNRs in NGC6946 with WIYN & GMOS (Long+, 2019)
J/ApJ/875/136 : BVRI, sp. & IR obs. of type II-P SN2017eaw (Van Dyk+, 2019)
J/ApJ/881/54 : Masses of SNR progenitors in M83 (Williams+, 2019)
J/MNRAS/482/384 : Core-collapse SNe ages and metallicities (Xiao+, 2019)
J/ApJ/899/14 : Opt. & FeII sources in SNR with HST (Long+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 9 A9 --- Image Image Name
11- 15 I5 --- PID [12331/15216] HST Proposal identification number
17- 20 I4 yr Obs.Y [2010/2019] Observation date, year
22- 23 I2 "month" Obs.M Observation date, month
25- 26 I2 d Obs.D Observation date, day in month
28- 36 F9.5 deg RAdeg [308.5/309] Right Ascension, center of image (J2000)
38- 45 F8.5 deg DEdeg [60/60.3] Declination, center of image (J2000)
47- 55 F9.5 deg V3 [177/347] V3 Axis
57- 59 I3 s Exp [520/987] Exposure Time
61- 64 A4 --- Cam Camera ("ACS" or "WFC3")
66- 70 A5 --- Filt Filter
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Object identifier
13- 20 A8 --- BFilt Bluer Filter
22- 25 F4.1 mag BComp [26.8/28.6] Blue filter, 50% Completeness
27- 34 A8 --- RFilt Redder Filter
36- 39 F4.1 mag RComp [25.8/28.5] Redder filter, 50% Completeness
41- 43 I3 --- Ns [2/228] Star count along line of sight
45- 47 F3.1 --- dAv [0/2.2] Spread of extinction along line of sight
49- 52 F4.2 mag Av [0.5/2.4] Reddening, V band
54- 57 F4.1 Msun Mass [7.5/59.1] Mass
59- 62 F4.1 Msun E_Mass [0.2/17.1] Upper uncertainty in Mass
64- 67 F4.1 Msun e_Mass [0.1/48.8] Lower uncertainty in Mass
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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- 11 A11 --- Name NGC 6946 Supernova Remnant ID (1)
13- 19 A7 --- OName Other identifier (2)
21- 22 I2 h RAh [20] Hour of Right Ascension (J2000)
24- 25 I2 min RAm [34/35] Minute of Right Ascension (J2000)
27- 31 F5.2 s RAs Second of Right Ascension (J2000)
33- 33 A1 --- DE- Sign of the Declination (J2000)
34- 35 I2 deg DEd [60] Degree of Declination (J2000)
37- 38 I2 arcmin DEm [4/13] Arcminute of Declination (J2000)
40- 43 F4.1 arcsec DEs Arcsecond of Declination (J2000)
45- 47 A3 --- Flag Use Flag (3)
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Note (1): Long et al. (2019, J/ApJ/875/85 and 2020, J/ApJ/899/14)
Note (2): Long et al. (2020, J/ApJ/899/14)
Note (3): The use flag indicates how the SNR was or was not used in our
analysis. We separate our locations into the following categories:
p = Progenitor mass constrained from measured local young population;
h = Progenitor mass constrained by measured local population, but with
filters that include some emission lines (see Section 2.6);
n = No young population detected in the fit (Type Ia candidate);
i = Insufficient photometry for a measurement; fitting failed;
o = Outside of the HST coverage; no measurement performed.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name NGC 6946 Supernova Remnant ID
13- 16 F4.1 [yr] T1 [4/44.7] Beginning of age bin in log(age)
18- 21 F4.1 [yr] T2 [4.5/50.1] End of age bin in log(age)
23- 32 E10.4 Msun/yr SFR [0/0.12] Best-fit star formation rate
34- 43 E10.4 Msun/yr e_SFR [0/0.1] Lower uncertainty on SFR
45- 54 E10.4 Msun/yr E_SFR [0/0.08] Upper uncertainty on SFR
56- 60 F5.3 --- PDF [0/1] Fraction of stellar mass <50Myr (1)
62- 66 F5.3 --- e_PDF [0/1] Lower uncertainty on PDF
68- 72 F5.3 --- E_PDF [0/1] Upper uncertainty on PDF
74- 78 F5.3 --- CDF [0/1] Cumulative fraction of stellar mass over
time (1)
80- 84 F5.3 --- e_CDF [0/1] Lower uncertainty on CDF
86- 90 F5.3 --- E_CDF [0.003/1] Upper uncertainty on CDF
92- 95 F4.1 Msun M1 [7.3/52.1] Lower range of mass of stars with
lifetimes within age bin
97-100 F4.1 Msun M2 [7.7/66.6] Upper range of mass of stars with
lifetimes within age bin
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Note (1): According to the best-fit SFH equivalent to the probability of that
progenitor age.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmnanuelle Perret [CDS] 22-Dec-2022