SWEETSPOT: NEAR-INFRARED OBSERVATIONS OF 13 TYPE Ia SUPERNOVAE FROM A NEW NOAO SURVEY PROBING THE NEARBY SMOOTH HUBBLE FLOW

Sasdelli

et al. 2016

ApJ

Photometric and spectroscopic observations of a slowly declining, luminous Type Ia supernova (SN Ia) SN 2011hr in the starburst galaxy NGC 2691 are presented. SN 2011hr is found to peak at M B = −19.84 ± 0.40 mag, with a post-maximum decline rate ∆m 15 (B) = 0.92 ± 0.03 mag. From the maximum-light bolometric luminosity, L = (2.30 ± 0.90) × 10 43 erg s −1 , we estimate the mass of synthesized 56 Ni in SN 2011hr to be M ( 56 Ni) = 1.11 ± 0.43 M . SN 2011hr appears more luminous than SN 1991T at around maximum light, and the absorption features from its intermediate-mass elements (IMEs) are noticeably weaker than the latter at similar phases. Spectral modeling suggests that SN 2011hr has the IMEs of ∼ 0.07 M in the outer ejecta, which is much lower than the typical value of normal SNe Ia (i.e., 0.3 -0.4 M ) and is also lower than the value of SN 1991T (i.e., ∼ 0.18 M ). These results indicate that SN 2011hr may arise from a Chandrasekhar-mass white dwarf progenitor that experienced a more efficient burning process in the explosion. Nevertheless, it is still possible that SN 2011hr may serve as a transitional object connecting the SN 1991T-like SNe Ia with the superluminous subclass like SN 2007if given that the latter also shows very weak IMEs at all phases.

Section: Discussionmentioning

confidence: 99%

Section: Distancementioning

confidence: 99%

A LUMINOUS PECULIAR TYPE IA SUPERNOVA SN 2011HR: MORE LIKE SN 1991T OR SN 2007if?

Sasdelli

et al. 2016

ApJ

“…The vast majority of objects are observed only after maximum and/or are sparsely sampled, and hence cannot be included in our current analysis. In particular, we are not able to use any objects from the large sample of the Sweetspot survey Weyant et al (2014Weyant et al ( , 2017. Our full Hubble-flow data set is shown in Table 2.…”

Section: Datamentioning

confidence: 99%

Measuring the Hubble constant with Type Ia supernovae as near-infrared standard candles

Dhawan

Jha

Leibundgut

2018

A&A

Self Cite

185

136

The most precise local measurements of H 0 rely on observations of Type Ia supernovae (SNe Ia) coupled with Cepheid distances to SN Ia host galaxies. Recent results have shown tension comparing H 0 to the value inferred from CMB observations assuming ΛCDM, making it important to check for potential systematic uncertainties in either approach. To date, precise local H 0 measurements have used SN Ia distances based on optical photometry, with corrections for light curve shape and colour. Here, we analyse SNe Ia as standard candles in the near-infrared (NIR), where luminosity variations in the supernovae and extinction by dust are both reduced relative to the optical. From a combined fit to 9 nearby calibrator SNe with host Cepheid distances from Riess et al. (2016) and 27 SNe in the Hubble flow, we estimate the absolute peak J magnitude M J = −18.524 ± 0.041 mag and H 0 = 72.8 ± 1.6 (statistical) ± 2.7 (systematic) km s −1 Mpc −1 . The 2.2% statistical uncertainty demonstrates that the NIR provides a compelling avenue to measuring SN Ia distances, and for our sample the intrinsic (unmodeled) peak J magnitude scatter is just ∼0.10 mag, even without light curve shape or colour corrections. Our results do not vary significantly with different sample selection criteria, though photometric calibration in the NIR may be a dominant systematic uncertainty. Our findings suggest that tension in the competing H 0 distance ladders is likely not a result of supernova systematics that could be expected to vary between optical and NIR wavelengths, like dust extinction. We anticipate further improvements in H 0 with a larger calibrator sample of SNe Ia with Cepheid distances, more Hubble flow SNe Ia with NIR light curves, and better use of the full NIR photometric data set beyond simply the peak J-band magnitude.

“…ESO428-G014 (also called IRAS01745-2914, MCG-05-18-002), is a southern barred early-type spiral galaxy [SAB(r)], at a distance of ~23.3 Mpc (NED, Weyant et al, 2014;scale=112 pc/arcsec). This galaxy has a highly obscured (CT, NH>10 25 cm -2 ) Seyfert Type 2 nucleus, with a low ratio of hard X-ray (2-10 keV) observed flux to [OIII] λ5007 (Maiolino et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Discovery of a Kiloparsec Extended Hard X-Ray Continuum and Fe–Kα from the Compton Thick AGN ESO 428-G014

Fabbiano

Elvis

Paggi

et al. 2017

ApJL

We report the discovery of kpc-scale diffuse emission in both the hard continuum (3-6 keV) and in the Fe Kα line in the Compton thick (CT) Seyfert galaxy ESO428-G014. This extended hard component contains at least ~24% of the observed 3-8 keV emission, and follows the direction of the extended optical line emission (ionization cone) and radio jet. The extended hard component has ~0.5% of the intrinsic 2-10 keV luminosity within the bi-cones. A uniform scattering medium of density 1 cm -3 would produce this luminosity in a 1kpc path length in the bi-cones. Alternatively, higher column density molecular clouds in the disk of ESO428-G014 may be responsible for these components. The continuum may also be enhanced by the acceleration of charged particles in the radio jet. The steeper spectrum (Γ ~ 1.7±0.4) of the hard continuum outside of the central 1.5'' radius nuclear region suggests a contribution of scattered/fluorescent intrinsic Seyfert emission. Ultrafast nuclear outflows cannot explain the extended Fe Kα emission. This discovery suggests that we may need to revise the picture at the base of our interpretation of CT AGN spectra.