Mildly Suppressed Star Formation in Central Regions of MaNGA Seyfert Galaxies

Negative feedback from accretion onto super-massive black holes (SMBHs), that is to remove gas and suppress star formation in galaxies, has been widely suggested. However, for Seyfert galaxies which harbor less active, moderately accreting SMBHs in the local universe, the feedback capability of their black hole activity is elusive. We present spatially-resolved H$\alpha$ measurements to trace ongoing star formation in Seyfert galaxies and compare their specific star formation rate with a sample of star-forming galaxies whose global galaxy properties are controlled to be the same as the Seyferts. From the comparison we find that the star formation rates within central kpc of Seyfert galaxies are mildly suppressed as compared to the matched normal star forming galaxies. This suggests that the feedback of moderate SMBH accretion could, to some extent, regulate the ongoing star formation in these intermediate to late type galaxies under secular evolution.Comment: 12 pages, 7 figures, accepted by MNRA

What drives the velocity dispersion of ionized gas in star-forming galaxies?

We analyze the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation rates (SFRs), SFR surface densities ($\rm{\Sigma_{SFR}}$), stellar masses and stellar mass surface densities ($\rm{\Sigma_{*}}$). By combining with high z galaxies, we found that there is a good correlation between the velocity dispersion and the SFR as well as $\rm{\Sigma_{SFR}}$. But the correlation between the velocity dispersion and the stellar mass as well as $\rm{\Sigma_{*}}$ is moderate. By comparing our results with predictions of theoretical models, we found that the energy feedback from star formation processes alone and the gravitational instability alone can not fully explain simultaneously the observed velocity-dispersion/SFR and velocity-dispersion/$\rm{\Sigma_{SFR}}$ relationships.Comment: 11 pages, 11 figures. Accepted for publication in MNRA

Host galaxy properties of changing-look AGNs revealed in the MaNGA survey

Changing-look active galactic nuclei (CL-AGNs) are a subset of AGNs in which the broad Balmer emission lines appear or disappear within a few years. We use the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey to identify five CL-AGNs. The 2D photometric and kinematic maps reveal common features as well as some unusual properties of CL-AGN hosts as compared to the AGN hosts in general. All MaNGA CL-AGNs reside in the star-forming main sequence, similar to MaNGA non-changing-look AGNs (NCL-AGNs). The 80 ± 16 per cent of our CL-AGNs do possess pseudo-bulge features, and follow the overall NCL-AGN MBH–σ∗ relationship. The kinematic measurements indicate that they have similar distributions in the plane of angular momentum versus galaxy ellipticity. MaNGA CL-AGNs, however, show a higher, but not statistically significant (20 ± 16 per cent) fraction of counter-rotating features compared to that (1.84 ± 0.61 per cent) in general star formation population. In addition, MaNGA CL-AGNs favour more face-on (axial ratio > 0.7) than that of type I NCL-AGNs. These results suggest that host galaxies could play a role in the CL-AGN phenomenon

What drives the velocity dispersion of ionized gas in star-forming galaxies?

We analyse the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation rates (SFRs), SFR surface densities (⁠ΣSFR⁠), stellar masses, and stellar mass surface densities (Σ∗). By combining with high z galaxies, we found that there is a good correlation between the velocity dispersion and the SFR as well as ΣSFR⁠. But the correlation between the velocity dispersion and the stellar mass as well as Σ∗ is moderate. By comparing our results with predictions of theoretical models, we found that the energy feedback from star formation processes alone and the gravitational instability alone cannot fully explain simultaneously the observed velocity–dispersion/SFR and velocity–dispersion/ΣSFR relationships

Massive Optically Dark Galaxies Unveiled by JWST Challenge Galaxy Formation Models

Over the past decade, the existence of a substantial population of optically invisible, massive galaxies at $z\gtrsim3$ has been implied from mid-infrared to millimeter observations. With the unprecedented sensitivity of the JWST, such extremely massive galaxy candidates have immediately been identified even at $z>7$, in much larger numbers than expected. These discoveries raised a hot debate. If confirmed, early, high-mass galaxies challenge the current models of galaxy formation. However, the lack of spectroscopic confirmations leads to uncertain stellar mass ($M_{\star}$) estimates, and the possible presence of active galactic nuclei (AGN) adds further uncertainty. Here, we present the first sample of 36 dust-obscured galaxies with robust spectroscopic redshifts at $z_{\rm spec}=5-9$ from the JWST FRESCO survey. The three most extreme sources at $z\sim5-6$ ($\sim$1 billion years after the Big Bang) are so massive (log$M_{\star}/M_{\odot}$ $\gtrsim11.0$) that they would require, on average, about 50% of the baryons in their halos to be converted into stars -- two to three times higher than even the most efficient galaxies at later times. The extended emission of these galaxies suggests limited contribution by AGN. This population of ultra-massive galaxies accounts for 20% of the total cosmic star formation rate density at $z\sim5-6$, suggesting a substantial proportion of extremely efficient star formation in the early Universe.Comment: Submitted to Nature. 22 pages, 4 main figures, 7 supplementary figures, 3 supplementary tables. Comments are welcom

Cartographier la formation d'étoiles à grand resdhift avec les relevés cosmologiques NIKA2

Cette thèse se concentre sur l’étude des galaxies poussiéreuses à grand décalage vers le rouge et de la formation d’étoiles dans l’Univers. Elle a été réalisée dans le cadre des relevés profonds cosmologiques avec NIKA2 (N2CLS), un instrument récent installé sur le télescope de 30m de l’IRAM. Un nouveau cadre d’analyse est développé pour les données N2CLS pour estimer précisément les biais dans la détection des sources et les mesures de flux. Grâce à ce cadre, nous mesurons les comptages de source à 1,2 et 2 mm dans le relevé N2CLS avec une profondeur et une couverture en flux sans précédent. Pour la première fois, nous tenons compte de l’impact du regroupement des sources et de leur superposition sur les comptages. Nous comparons nos résultats avec les observations provenant des interféromètres et les modèles d’évolution de galaxies. Cette comparaison révèle un excès de sources brillantes par rapport à la plupart des modèles .La thèse porte également sur la stratégie de mesure des décalage vers le rouge (z) pour notre échantillon de galaxies poussiéreuses. Nous introduisons une nouvelle méthode pour contraindre le z des sources en utilisant conjointement la photométrie multi-longueur d’ondes et la spectroscopie NOEMA. La méthode prouve son efficacité et sa robustesse sur cinq sources issues des données de vérification scientifique de NIKA2. Cette méthode automatique pourra être appliquée à de grands échantillons de données millimétriques. L’étude sur ces 5 sources permet de concevoir la stratégie de suivi de notre échantillon complet de N2CLS et les premiers résultats sur le champ GOODS-N sont également présentésThis thesis focus on the studies on high-redshift dusty galaxies and obscured star formation using the NIKA2 cosmological legacy survey (N2CLS). This survey is using 300h of NIKA2, a recent continuum camera installed on the IRAM 30m telescope. A new analysis framework for N2CLS is developed to more completely estimate biases in high-z source detection and flux measurements. With this framework, we measure the number counts at 1.2 and 2 mm with unprecedented depth and flux coverage. For the first time, we account for the impact of sources blending and clustering on single dish number counts and make fair comparison of our results with interferometric observations and models. An excess of bright sources relative to most models is noticed from the comparison. The thesis also works on the strategy of efficient redshift measurements on large sample of obscured galaxies for studying the cosmic history of obscured star formation. We introduce a new method to jointly constrain the source redshift with the information from the multiwavelegth photometry and NOEMA spectroscopy. The method proves its effectiveness and robustness on five sources from NIKA2 science verification data. We highlight the application of this highly automatic method to large millimeter datasets, including N2CLS, and design the follow-up strategy on the N2CLS GOODS-N sample, where the first results are also presente

Mildly suppressed star formation in central regions of MaNGA Seyfert galaxies

Negative feedback from accretion on to supermassive black holes (SMBHs), that is to remove gas and suppress star formation in galaxies, has been widely suggested. However, for Seyfert galaxies which harbour less active, moderately accreting SMBHs in the local Universe, the feedback capability of their black hole activity is elusive. We present spatially resolved H α measurements to trace ongoing star formation in Seyfert galaxies and compare their specific star formation rate with a sample of star-forming galaxies whose global galaxy properties are controlled to be the same as the Seyferts. From the comparison, we find that the star formation rates within central kpc of Seyfert galaxies are mildly suppressed as compared to the matched normal star-forming galaxies. This suggests that the feedback of moderate SMBH accretion could, to some extent, regulate the ongoing star formation in these intermediate to late type galaxies under secular evolution

Mildly suppressed star formation in central regions of MaNGA Seyfert galaxies

Negative feedback from accretion on to supermassive black holes (SMBHs), that is to remove gas and suppress star formation in galaxies, has been widely suggested. However, for Seyfert galaxies which harbour less active, moderately accreting SMBHs in the local Universe, the feedback capability of their black hole activity is elusive. We present spatially resolved H α measurements to trace ongoing star formation in Seyfert galaxies and compare their specific star formation rate with a sample of star-forming galaxies whose global galaxy properties are controlled to be the same as the Seyferts. From the comparison, we find that the star formation rates within central kpc of Seyfert galaxies are mildly suppressed as compared to the matched normal star-forming galaxies. This suggests that the feedback of moderate SMBH accretion could, to some extent, regulate the ongoing star formation in these intermediate to late type galaxies under secular evolution

What drives the velocity dispersion of ionized gas in star-forming galaxies?

We analyse the intrinsic velocity dispersion properties of 648 star-forming galaxies observed by the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, to explore the relation of intrinsic gas velocity dispersions with star formation rates (SFRs), SFR surface densities (⁠ΣSFR⁠), stellar masses, and stellar mass surface densities (Σ∗). By combining with high z galaxies, we found that there is a good correlation between the velocity dispersion and the SFR as well as ΣSFR⁠. But the correlation between the velocity dispersion and the stellar mass as well as Σ∗ is moderate. By comparing our results with predictions of theoretical models, we found that the energy feedback from star formation processes alone and the gravitational instability alone cannot fully explain simultaneously the observed velocity–dispersion/SFR and velocity–dispersion/ΣSFR relationships