Research focuses on supernovae, particularly Type Ia Supernova Cosmology, stellar populations, and their environments. This includes studies on progenitor age bias, cosmic distance measurements, large-scale structure, photometric and spectral classification of supernovae, progenitor metallicity, cosmic expansion anisotropy, host galaxy properties, dust distribution, and the diversity of thermonuclear supernova populations.

초신성, 특히 Ia형 초신성 우주론, 항성 개체수 및 그 환경에 대한 연구에 중점을 둡니다. 여기에는 전구체 나이 편향, 우주 거리 측정, 거대 구조, 초신성의 측광 및 스펙트럼 분류, 전구체 금속성, 우주 팽창 비등방성, 숙주 은하 특성, 먼지 분포 및 열핵 초신성 개체군의 다양성에 대한 연구가 포함됩니다.

Early-type Host Galaxies of Type Ia Supernovae. II. Evidence for Luminosity Evolution in Supernova Cosmology

The Prevalence and Influence of Circumstellar Material around Hydrogen-rich Supernova Progenitors

New Modules for the SEDMachine to Remove Contaminations from Cosmic Rays and Non-target Light: byecr and contsep

Environmental Dependence of Type Ia Supernova Luminosities from a Sample without a Local–Global Difference in Host Star Formation

Accuracy of environmental tracers and consequences for determining the Type Ia supernova magnitude step

A Uniform Type Ia Supernova Distance Ladder with the Zwicky Transient Facility: Absolute Calibration Based on the Tip of the Red Giant Branch Method

The Type II supernova SN 2020jfo in M 61, implications for progenitor system, and explosion dynamics

Environmental Dependence of Type Ia Supernova Luminosities from the YONSEI Supernova Catalog

ZTF SN Ia DR2: The diversity and relative rates of the thermonuclear supernova population

ZTF SN Ia DR2: Colour standardisation of type Ia supernovae and its dependence on the environment

SN 2020bqj: A Type Ibn supernova with a long-lasting peak plateau

Two c's in a pod: Cosmology independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair

SN 2021adxl: A luminous nearby interacting supernova in an extremely low-metallicity environment

ZTF SN Ia DR2: Study of Type Ia supernova light-curve fits

ZTF SN Ia DR2: The spectral diversity of Type Ia supernovae in a volume-limited sample

ZTF SN Ia DR2: Simulations and volume-limited sample

ZTF SN Ia DR2: Searching for late-time interaction signatures in Type Ia supernovae from the Zwicky Transient Facility

TiDES: The 4MOST Time Domain Extragalactic Survey

Galaxy Spectra neural Network (GaSNet). II. Using deep learning for spectral classification and redshift predictions

Peculiar velocity cosmology with type Ia supernovae

Strong Progenitor Age Bias in Supernova Cosmology. III. Progenitor Age as the Physical Origin of the Type Ia Supernova Magnitude Steps with Host Properties

How Robust Is the Cosmic Distance with the Tip of Red Giant Branch against Stellar Population Variations?

Illuminating the Local Universe: Large-Scale Structure from ZTF Type Ia Supernovae

Photometric classification of supernovae detected by the Zwicky Transient Facility using noise augmentation

ZTF SN Ia DR2 follow-up: Characterization of subluminous Type Ia supernovae in the ZTF DR2 full sample

Study of the anisotropy of cosmic expansion on ZTF type Iasupernovae simulations

ZTF SN Ia DR2 follow-up: Exploring the origin of the Type Ia supernova host galaxy step through Si II velocities

ZTF-SEDm Type Ia supernova sample for Twins Embedding spectrophotometric standardisation

Testing the effect of the progenitor metallicity on the 56Ni mass and constraining the progenitor scenarios in Type Ia supernovae

VizieR Online Data Catalog: ZTF SN Ia DR2 follow-up (Alburai+, 2026)

A real-time search for Type Ia Supernovae with late-time interactions with circumstellar material in ZTF data

ZTF SN Ia DR2: Cosmology-independent constraints on Type Ia supernova standardisation from supernova siblings

VizieR Online Data Catalog: SNII during ZTF 1st phase survey with follow-up sp. (Bruch+, 2023)

Testing and combining transient spectral classification tools on 4MOST-like blended spectra

Tracing back the birth environments of Type Ia supernova progenitor stars

ZTF SN Ia DR2: Improved SN Ia colors through expanded dimensionality with SALT3+

CCSNscore: A Multi-input Deep Learning Tool for Classification of Core-collapse Supernovae Using SED-machine Spectra

ZTF SN Ia DR2: Environmental dependencies of stretch and luminosity for a volume-limited sample of 1000 type Ia supernovae

ZTF SN Ia DR2: High-velocity components in the Si IIλ6355

VizieR Online Data Catalog: ZTF SN Ia DR2. SiII6355 high-velocity comp. (Harvey+, 2025)

ZTF SN Ia DR2: An environmental study of Type Ia supernovae using host galaxy image decomposition

ZTF SN Ia DR2: Evidence of changing dust distribution with redshift using type Ia supernovae

ZTF SN Ia DR2: Exploring SN Ia properties in the vicinity of under-dense environments

ZTF SN Ia DR2: Impact of the galaxy cluster environment on the stretch distribution of Type Ia supernovae

ZTF SN Ia DR2: Overview

ZTF SN Ia DR2: Properties of the low-mass host galaxies of Type Ia supernovae in a volume-limited sample

ZTF SN Ia DR2: Secondary maximum in type Ia supernovae

VizieR Online Data Catalog: Spectral Measurements of ZTF SN Ia DR2 (Burgaz+, 2025)

VizieR Online Data Catalog: ZTF DR1 light curves of SNe Type Ia (Dhawan+, 2022)

VizieR Online Data Catalog: ZTF SN Ia DR2 (Dimitriadis+, 2025)

How Accurate are Transient Spectral Classification Tools?— A Study Using 4646 SEDMachine Spectra

VizieR Online Data Catalog: Multi-band light curve of SN 2021adxl (Brennan+, 2024)

VizieR Online Data Catalog: ZTF SN Ia DR2. Secondary maximum in Type Ia SN (Deckers+, 2025)

VizieR Online Data Catalog: SN 2020alm spectrum (Terwel+, 2025)

Tracing back the birth environments of Type Ia supernova progenitor stars: a pilot study based on 44 early-type host galaxies

Reconsidering photometric estimation of local star formation environment and its correlation with Type Ia supernova luminosity

VizieR Online Data Catalog: ZTF Type II supernovae with follow-up obs. (Bruch+, 2021)

The Zwicky Transient Facility Type Ia supernova survey: first data release and results

Two c's in a pod: cosmology-independent measurement of the Type Ia supernova colour-luminosity relation with a sibling pair

Within the volume-limited subsample at z < 0.06 of the Zwicky Transient Facility (ZTF) DR2 sample, we confirm a statistically significant excess of Type Ia supernovae (SNe Ia) at z ≃ 0.02 - 0.04 , previously reported but not explained by survey selection effects. Forward simulations assuming a uniform volumetric SN Ia rate and realistic ZTF detection efficiencies fail to reproduce the feature at the 5 - 7 σ level. We also detect an excess in the rates compared to our survey simulations at z ≃ 0.08 and 0.14 , albeit at smaller significance. To investigate the origin of these inhomogeneities, we compare the observed SN distribution to constrained reconstructions of the local matter density field from the Manticore project, based on Bayesian forward modelling of the 2M++ galaxy catalogue. While SN overdensities are spatially associated with prominent nearby structures such as the Perseus, Coma, and Hercules superclusters, the amplitude of the SN excesses significantly exceeds that expected from matter overdensities alone. By reconstructing a redshift-dependent volumetric SN Ia rate, we find that local enhancements can reach factors of two to five within specific clusters, while the sample-averaged rate remains consistent with previous low-redshift measurements. These results indicate that the SN Ia rate is not a linear tracer of the underlying matter density and suggest a strong environmental dependence in dense structures. We discuss possible physical origins and highlight the implications for low-redshift SN cosmology, including correlated peculiar velocities and additional covariance beyond standard linear corrections.

This paper has two aims: the first one is to build a large homogeneous spectrophotometric Type Ia supernova (SN Ia) sample, using 3069 spectra from the second Zwicky Transient Facility data release (ZTF DR2). Using this sample we reproduce, as the second objective of the paper, the Twins Embedding (TE) spectrophotometric standardisation method, which led to an exceptionally low value of 0.073 mag for the intrinsic scatter. We improve the flux-calibration accuracy of the SEDm SN Ia spectral sample using the ZTF photometric data, which are calibrated at the percent level. We then apply the three steps of the TE parameterisation to a subset of 783 ZTF SN spectra near maximum light, and analyse the resulting standardisation methods. The precision of the phase correction model, which is the first step of the TE, is estimated at 0.01 mag in g band, using ZTF data. Despite the challenge posed by the ZTF spectrum extraction pipeline, we apply a first standardisation in color based on the second step of the TE, the Read Between The Lines (RBTL). When considering the scatter due to the redshift error and the flux calibration error, we estimate a 0.129 mag Hubble residual scatter for this ZTF sample as an upper limit. As expected from the low spectral quality, the final TE standardisation based on three non-linear parameters did not improve the overall dispersion. We release 1897 flux calibrated spectra of 1607 SNe Ia with an estimated photometric accuracy of 0.07 mag. We further demonstrate the ability to apply a spectrophotometric standardisation with limited quality spectra. The RBTL standardisation is more efficient than that of SALT with one less parameter, and the resulting host steps are consistent with zero, making it less prone to astrophysical bias. For future spectroscopic surveys, a better spectral quality would enable the full TE standardisation to be computed. (Abridged)

Young-Lo Kim

Professor

Young-Lo Kim's Research Group

교수님 소개

Young-Lo Kim

연구실 소개

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

Strong Progenitor Age Bias in Supernova Cosmology. III. Progenitor Age as the Physical Origin of the Type Ia Supernova Magnitude Steps with Host Properties

How Robust Is the Cosmic Distance with the Tip of Red Giant Branch against Stellar Population Variations?

Illuminating the Local Universe: Large-Scale Structure from ZTF Type Ia Supernovae

연구실 보유 특허

대학별 입시끈

우리 연구실 모집

교수님 소개

Young-Lo Kim

연구실 키워드

알럼나이가 간 회사

연구실 지원 방법

대우 조건

연도별 논문 인용수

저널 & 학회 논문 출판 수

연구실 논문 목록

Strong Progenitor Age Bias in Supernova Cosmology. III. Progenitor Age as the Physical Origin of the Type Ia Supernova Magnitude Steps with Host Properties

How Robust Is the Cosmic Distance with the Tip of Red Giant Branch against Stellar Population Variations?

Illuminating the Local Universe: Large-Scale Structure from ZTF Type Ia Supernovae

연구실 보유 특허

최근 3년간 연구실적 높은 연구실

대학별 입시끈

우리 연구실 모집