Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userCharacterizing Intra-cluster light in the Hubble Frontier Fields
73
0
0.0
(
0
)
Authors
Takahiro Morishita
Ask ChatGPT about the research
No Arabic abstract
We investigate the intra-cluster light (ICL) in the 6 Hubble Frontier Field clusters at $0.3<z<0.6$. We employ a new method, which is free from any functional form of the ICL profile, and exploit the unprecedented depth of this Hubble Space Telescope imaging to map the ICLs diffuse light out to clustrocentric radii $Rsim300$kpc ($mu_{rm ICL}sim27$mag arcsec$^{-2}$). From these maps, we construct radial color and stellar mass profiles via SED fitting and find clear negative color gradients in all systems with increasing distance from the Brightest Cluster Galaxy (BCG). While this implies older/more metal rich stellar components in the inner part of the ICL, we find the ICL mostly consists of a $<2$Gyr population, and plausibly originated with $log M_*/M_odot<10$ cluster galaxies. Further, we find 10-15% of the ICLs mass at large radii ($>150$kpc) lies in a younger/bluer stellar population ($sim1$Gyr), a phenomenon not seen in local samples. We attribute this light to the higher fraction of starforming/(post-)starburst galaxies in clusters at $zsim0.5$. Ultimately, we find the ICLs total mass to be $log M_{rm *}^{rm ICL}/M_odotsim11$-12, constituting 5%-20% of the clusters total stellar mass, or about a half of the value at $zsim0$. The above implies distinct formation histories for the ICL and BCGs/other massive cluster galaxies; i.e. the ICL at this epoch is still being constructed rapidly ($sim40M_odot$yr$^{-1}$), while the BCGs have mostly completed their evolution. To be consistent with the ICL measurements of local massive clusters, such as the Virgo, our data suggest mass acquisition mainly from quiescent cluster galaxies is the principal source of ICL material in the subsequent $sim$5 Gyr of cosmic time.
rate research
Read More
We present a joint optical/X-ray analysis of the massive galaxy cluster Abell 2744 (z=0.308). Our strong- and weak-lensing analysis within the central region of the cluster, i.e., at R<1Mpc from the brightest cluster galaxy, reveals eight substructures, including the main core. All of these dark-matter halos are detected with a significance of at least 5sigma and feature masses ranging from 0.5 to 1.4x10^{14}Msun within R<150kpc. Merten et al. (2011) and Medezinski et al. (2016) substructures are also detected by us. We measure a slightly higher mass for the main core component than reported previously and attribute the discrepancy to the inclusion of our tightly constrained strong-lensing mass model built on Hubble Frontier Fields data. X-ray data obtained by XMM-Newton reveal four remnant cores, one of them a new detection, and three shocks. Unlike Merten et al. (2011), we find all cores to have both dark and luminous counterparts. A comparison with clusters of similar mass in the MXXL simulations yields no objects with as many massive substructures as observed in Abell 2744, confirming that Abell 2744 is an extreme system. We stress that these properties still do not constitute a challenge to $Lambda$CDM, as caveats apply to both the simulation and the observations: for instance, the projected mass measurements from gravitational lensing and the limited resolution of the sub-haloes finders. We discuss implications of Abell 2744 for the plausibility of different dark-matter candidates and, finally, measure a new upper limit on the self-interaction cross-section of dark matter of sigma_{DM}<1.28cm2/g(68% CL), in good agreement with previous results from Harvey et al. (2015).
In this paper we present the results of our search for and study of $z gtrsim 6$ galaxy candidates behind the third Frontier Fields (FF) cluster, MACSJ0717.5+3745, and its parallel field, combining data from Hubble and Spitzer. We select 39 candidates using the Lyman Break technique, for which the clear non-detection in optical make the extreme mid-$z$ interlopers hypothesis unlikely. We also take benefit from $z gtrsim 6$ samples selected using previous Frontier Fields datasets of Abell 2744 and MACS0416 to improve the constraints on the properties of very high-redshift objects. We compute the redshift and the physical properties, such emission lines properties, star formation rate, reddening, and stellar mass for all Frontier Fields objects from their spectral energy distribution using templates including nebular emission lines. We study the relationship between several physical properties and confirm the trend already observed in previous surveys for evolution of star formation rate with galaxy mass, and between the size and the UV luminosity of our candidates. The analysis of the evolution of the UV Luminosity Function with redshift seems more compatible with an evolution of density. Moreover, no robust $zge$8.5 object is selected behind the cluster field, and few $z$$sim$9 candidates have been selected in the two previous datasets from this legacy survey, suggesting a strong evolution in the number density of galaxies between $z$$sim$8 and 9. Thanks to the use of the lensing cluster, we study the evolution of the star formation rate density produced by galaxies with L$>$0.03L$^{star}$, and confirm the strong decrease observed between $z$$sim$8 and 9.
In recent years, the rise in the number of Lyman Break Galaxies detected at high redshifts z >= 6 has opened up the possibility of understanding early galaxy formation physics in great detail. In particular, the faint-end slope (alpha) of the Ultra-violet luminosity function (UV LF) of these galaxies is a potential probe of feedback effects that suppress star formation in low mass haloes. In this work, we propose a proof-of-concept calculation for constraining the fluctuating UV background during reionization by constraining alpha in different volumes of the Universe. Because of patchy reionization, different volumes will experience different amount of photo-heating which should lead to a scatter in the measured alpha. Our approach is based on a simple model of the UV LF that is a scaled version of the halo mass function combined with an exponential suppression in the galaxy luminosity at the faint-end because of UV feedback. Although current data is not sufficient to constrain alpha in different fields, we expect that, in the near future, observations of the six lensed Hubble Frontier Fields with the James Webb Space Telescope (JWST) will offer an ideal test of our concept.
We searched for z > 7 Lyman-break galaxies (LBGs) in the optical-to-mid-infrared Hubble Frontier Field and associated parallel field observations of the strong-lensing cluster MACS J0416-2403. We discovered 22 candidates, of which six lie at z > 9 and one lies at z > 10. Based on the Hubble and Spitzer photometry, all have secure photometric redshifts and a negligible probability of being at lower redshifts, according to their peak probability ratios, R. This substantial increase in the number of known high-redshift galaxies allows a solid determination of the luminosity function at z > 8. The number of high-z candidates in the parallel field is considerably higher than that in the Abell 2744 parallel field. Our candidates have median stellar masses of log(M_*) ~ 8.40^{+0.55}_{-0.31}~Msun, SFRs of ~ 1.6^{+0.5}_{-0.4} Msun yr^-1, and SFR-weighted ages of < 310^{+70}_{-140} Myr. Finally, we are able to put strong constraints on the z = 7,8,9 and 10 luminosity functions. One of the objects in the cluster field is a z ~ 10 candidate, with a magnification of mu ~ 20 +- 13. This object is likely the faintest z ~ 10 object known to date, allowing a first look into the extreme faint-end (L ~ 0.04L*) of the z ~ 10 luminosity function.
We search for high-redshift dropout galaxies behind the Hubble Frontier Fields (HFF) galaxy cluster MACS J1149.5+2223, a powerful cosmic lens that has revealed a number of unique objects in its field. Using the deep images from the Hubble and Spitzer space telescopes, we find 11 galaxies at z>7 in the MACS J1149.5+2223 cluster field, and 11 in its parallel field. The high-redshift nature of the bright z~9.6 galaxy MACS1149-JD, previously reported by Zheng et al., is further supported by non-detection in the extremely deep optical images from the HFF campaign. With the new photometry, the best photometric redshift solution for MACS1149-JD reduces slightly to z=9.44 +/- 0.12. The young galaxy has an estimated stellar mass of (7 +/- 2)X10E8 Msun, and was formed at z=13.2 +1.9-1.6 when the universe was ~300 Myr old. Data available for the first four HFF clusters have already enabled us to find faint galaxies to an intrinsic magnitude of M(UV) ~ -15.5, approximately a factor of ten deeper than the parallel fields.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
